Thanks again @South Main Auto Repair for fixing my Cherokee! The 4.0 ran smooth as silk driving back to PA, no money light! Wife says I should keep it now that you fixed it... LOL
rtchrg440 sell it a run, run fast. I have been a Jeep owner for over 20 years...and still own two in the Family. I swear those vehicles are designed to make money for the Chrysler company in parts sales AFTER the initial vehicle sale.
I know what you mean. I was a faithful Toyota owner before I bought this XJ, never had a vehicle like this that always seems to need a part every other month. One thing I will say, I usually buy aftermarket parts for the Jeep to save money, and at least 50% of the time the part has failed in a year. So I really bought the part twice, and probably didn't save in the long run. Frustrating! This crank sensor was aftermarket (either from RockAuto or AutoZone, can't remember), and it was doing this from the beginning. I shot a ton of other parts at this Jeep thinking it was a legit misfire.
rtchrg440 I only go OEM for my Jeeps either new or the used parts market - from junkyards - that has recently and robustly sprung up on the internet in the last few years like partsmarket. Mopar rear drive shaft new $895, from the salvage yard $65 plus $50 for shipping and I can get one from States not in the rust belt. I tried the Chinese made parts once. Part was a rear window strut that holds up the window. Lasted 18 months. Then I purchased Mopar OEM and it so far has lasted 4 years.
rtchrg440 nice Jeep! I have a 2k XJ myself and I love it. I have the OEM sensor and after this video I might swap it in, got that tiny flutter going on but no money light. Have a great weekend.
What an odd and annoying fault because it is so indecisive. As someone else mentioned, the transient spikes after the new sensor were fitted seemed lower, so maybe it was just a connection resistance issue or the new sensor might have a low value capacitor in it as a filter. It could possibly be one of those things that didn't occur when they were writing the software, but as age crept in it became an issue. There are some industrial control systems where you have to use a specific brand of contactor because the auxiliary contact closure timing is so critical that the software shuts off the machine and flags it as a contactor fault if the wrong brand of contactor is used.
It's really annoying when the timing isn't critical to the job the machine is doing, it's just critical to the time that was programmed. Programmers set it up to see a value in a very short time like .002 seconds when it wouldn't matter if it took 5 seconds.
@@tiredoldmechanic1791 The rise/fall time on the aftermarket sensor most likely is causing the computer to get confused as it's not seeing a sharp transition to measure rotational acceleration. This allows it to run but not monitor itself. I suspect the "square" edge of the signal starts to round over. The programmer needs something consistent to trigger off to accurately measure acceleration. If we only cared about rpms I would agree that it's the programmer's fault. I'm a hardware guy and like to blame software too but this time it is not the programmer's fault. This suspected rounding (rc effect) is only visible if zoomed in. Then again I could be wrong as the data from the video is zoomed out way too far.
I remember a story where a huge diesel motor on a giant cruse ship wouldn't run. None of the technicians could figure out why. They gave up and called in an old retired dude. He looked at a while. Pulled a large hammer out a bag and gave it a hard WACK! It Stared up and ran perfectly. When he gave them the Bill it was for $10,000.00. They all freaked. "you didn't do anything" they said. Give us an itemized billing statement! The bill he produced said. One hammer blow: $8.99 Knowing where to hit: $9,991.01
"knowing where to hit" is ABSOLUTELY RIGHT! In so many cases we have to draw from our experiences, Eric knew which part to change and the old man knew where to hit. 1 + 1 is 2 because my 1st grade teacher taught me so. NEXT!
Eric I was wondering on that crank sensor do you think that the aftermarket sensor is a different kind of sensor then the OEM I know there are two different kind of sensors. One can be hall effect sensor and honestly I am not remembering the other type of sensor. Just a thought
It is one thing to shoot parts at it when nothing shows wrong but another to look up data talk to others and then take an educated guess very well done.
When I trained as a tech in the military we had a W.A.G. and a S.W.A.G. Wild assed guess or a scientific wild assed guess. ;) This was one of the later. I know, old video, but I enjoy watching them when they pop up in my feed.
Nice video on using what I teach as "educated guessing". Your video example is "NEEDED" is the "toolbox" of technicians or DIY wrench turners. In the real world sometimes things just don't make sense. Theres no visual or measurable evidence to go from and to fix the problem we turn to what I call "the medical method"....This is where you consider what worked for a 100 other people get healed and go for it. There is still much thought and consideration put into this decision based on research, peers and OEM support. Just reminds me how glad I am to be a technician most often working from pure evidence and not "practicing medicine"! Once agian, great job and I bet you would like my "Every Mechanic Should know This" Playlist. I'm a fan of South Main Auto videos for sure....Coach Conley
Hi Eric. Downloaded the files @2500 rpm and used Pico measument tools. Old sensor duty cycle is 10,28% New is 11,1%. 7% difference in pulse width -> upto 25 degree variation to angle speed dRpm. Old sensor became more insensitive detecting a flywheel teeth. Turned on later and turned off a earlier. Could this be the diagnosis?
Awesome! I wonder if the magnet on the crank starter wheel gets weaker with time and heat, thus the heavier wound and more sensitive mopar sensor is the only one accurate enough?
Thats what I thought. That maybe the aftermarket sensor is manufactured slightly differently that maybe the PCM wasn't getting the full value it was expecting.
Add Gm fuel pumps only & MAF sensors on GM cars. Been burned too often with non OEM parts. Cost more, but I only want to do it once. Especially dropping the tank for a fuel pump replacement
Had a 2000 Chrysler Sebring with the 2.5l V6. The engine would just die for no reason. Driving, at a stop or just idling, the engine would just die. At times, it would restart. At other times, it would take some time before the engine would fire up. No C/E light, no codes. Checked the crank sensor, it checked good. Wiring checked good. Everything checked good. I heard a similar thing of where the crank sensor would cause the engine to die. I replaced the crank sensor and all was fixed. Could be that the sensor was on its way out.
Hi Eric, very interesting case, I downloaded the waveforms and the only difference I could find was that the old sensor at idle and 2500 rpms the square signals from crank were longer time base wise idle= 697 us Old to idle= 472 us new at 2500 rpms old =216.9 us new= 133.3 us. Would that be enough to create false misfires counters?
MrBorntoroll the thing here is that there was no actual misfires, so this is more of a software glitch than an actual misfire. All cylinders showed misfire only on software.
I mean with the firing event we would have some more measurments as the pcm measures speed of the crankshaft after cyllinder firing to flag a missfire.
Ok. We kinda have spark events. The theory: if PCM counts time of crank rotation after spark event not until every next HIGH hump but until next for ex "big low gap and HIGH hump" (to give time for combustion to occur) then we can see that with old sensor be get quite bigger (in ms) time delay which can be calculated as missfire if PCM wants to see shorter time. The bad news: the theory doesn't work during idle.
Eric.....what's the chances the old crank sencor was a little loose or holes bigger then the bolts and causing vibration issues?...ran into that once b4...
most people say "i dont know" when asked when was the last time spark plugs were done (and on this....people forget the cap and rotor is a wear part) so i usually will pull a plug to have a gander . but ya.... ive shotgunned my own cars ignition (dont have time, and dont want to WORK on my own shitboxes) 99 GM 3.1...... waste spark can go F it self . new plugs and wires.... still had a soft miss that the CEL didnt light for but the old plugs WERE quite old, and the wires 10 years old.... . turned out..... bad coil then i tightened the bolt too much because it was -30f.... and cracked that coil . then i got a bad coil..... that split in half turned my car into a 4 banger..... limped my way into work . and finally..... ive had NO issues for 80,000 miles and now its about time to do the plugs again... . PS on my 97 4.0 jeep..... i have a miss that cant be felt (some times cly 5, some times random multi, or sometimes 2 5 and random) but its usually going down a hill, with like 2 gallons of gas in the tank.... . throws the code with in 200 feet of the same hill..... . doesnt seem to do it (as often) when it has 1/4+ tank of gas . oh well..... its a mopar..... reset the code, keep driving till something changes / gets worse enough to fix
Had a similar situation. Friend took his 4.0 Cherokee into the shop because of check engine light at highway speeds. Shop said it was indicating all 6 cylinders were showing a "spark" miss and they began replacing parts. ECM and Coil Pack and other parts to the tune of over $2650.00 in parts My friend asked if I could check with the shop and so I called just casually asked what waveform they were getting generated when they tested They said it was great and had never showed a bad waveform and that was what throwing their troubleshooting off. I quietly suggested that they might try changing the crankshaft sensor ( which they had not done to this point. It is not my vehicle or my right to get into the middle of the problem). Long story short, they changed the crank sensor and the wave forms returned to normal. Sadly, of course they just added the cost of the crank sensor to the $2650.00 parts plus labor bill telling my friend that somehow the "ECM had defaulted in it's code and caused other parts such as the coil pack and crankshaft sensor to fail". I explained to my friend that such thing just could not happen and if he wanted to dispute the charges I would be willing to help him but he would need to start the process not me. He never did anything about it so he received an education, I received an education and I am sure the shop received an education. Aloha from Maui
So, what is the ethical way to run through this parts changing fusillade, short of bringing it to Eric "the Swami" @ SMA ? I got $9,899.00 hammers too, but feel bad using them.
Another excellent video from SMA. Thanks and look for some family ice cream $$ in your PayPal account. My thoughts on the misfire counters and DTC - the diagnostic calibrator(s) for the components and misfire DTCs for obvious reasons use new OEM parts and 6 SIGMA calculations base on data to establish failure thresholds. It maybe the replaced (aftermarket?) part slowly drifted out of specs, resulting in misfire counters climbing and the DTC setting. The component failure DTC 'should' have caught the drift, but that's a tough one to catch.
awesome diagnosis and work. I actually did one of these jobs while I was in a high school auto shop class! of course, My school didn't have any real awesome scope software or anything. After WEEKS of testing with a DVOM, I had isolated the crankshaft sensor, and replaced it and verified the fix. My shop teacher was super impressed with me. I owe all my success to the man.
On the 4.0 these things (CS) go bad intermittently ... usually a thermal breakdown causing "no start" ... stars after cooling down ... cheap repair (but use an OEM one)
Recently replaced a 4.3 engine. Got a P0300 code when holding down throttle over 2000rpm. Money light flashes says cylinder 1 and 4 are misfiring. Can't feel any misfire in engine. Could it need a crank relearn? And if so, what scanners can do a crank relearn? Thanks...
Having same issue with a 01 Jeep Wrangler at the shop. At 3K RPM shows ghost misfires. I put an aftermarket sensor and didn't help, guess ill go OEM. I noticed you didn't relearn the misfire counter when installing the new crank sensor. You can see and your scanner it says adaptive learned no. That's why it wasn't showing misfires. I know because when I changed the crank sensor it wasn't misfiring again until it learned the misfire monitor. You fixed it though since the vehicle never returned.
Jeeps do not like non-OEM sensors. It's just that simple. I know this from experience on a 2007 Jeep GC 5.7l. Go to the dealer and pay the man for the Mopar part. It's better that 3 trips to Advance (Buy the part, exchange the part that didn't work, refund the part)and then one to Jeep .
Scott Berger I own a 2001 Chrysler Sebring convertible LXI, needed to replace the engine as a rod had come through the block by my soninlaw. It wouldn't give a green light to pass emissions so I took it to the dealer for an inspection sticker. What I got was no sticker and 14 pages printed out with defects. Upper and lower ball joints were bad and a whole host of problems. All four yeah four O2 sensors needed to be replaced again because he didn't know Chrysler products require factory O2 sensors to work properly. After replacing the last O2 sensor the scanner finally lights up green light. Dealer wanted $2897.41 to fix and give the car a sticker. Cost me just over $1200.00 to fix everything. Using an old school mechanic at his own shop. Took over 6 months as I was on a budget. The wife's idea of maintenance is put gas in it and stick the key in it. That was 5 years ago, just finished replacing the oil seals between the engine and transmission.$ quote was $600 actual cost just under a K. Both engine mounts needed replacing, massive aluminum mounts. The rubber had broken through on both of them. What's left? Drivers door motor and right rear window motor then everything will work as intended. Ahhh. The pleasures of vehicle ownership when your wife refuses to listen to my advice. I lost her last year after a medical issue. Now finally in another month I will have the car back to factory specifications. After seeing what you went through replacing a window motor I think I'll include the regulator with the motor on the drivers door. Cheers!
My 02 wrangler 4.0 had the same problem. Found out that the sensor has a felt pad on it you need to mash it into the flywheel and it wipes the felt off. The oem came with instalation instructions saying to do it, reinstalled the aftermarket one mashing it in and worked perfectly, couldn't find anything anywhere online to help.
I've found that gut and others experiences have bettered the high priced scanners alot of the time most customers do not understand the scanner jargon great video Eric O
From an electronics point of view, I can't find the specs for the picoscope, but I suspect that the aftermarket ckp is producing noise on the signal line that is too fast for the Pico to catch. Next time I get one of these in the shop I'm going to use a 200mHz scope on it and see what there is to see. Maybe it's nothing but, that sensor HAS to be producing something the ECM doesn't like. We just have to find it.
I have seen this on multiple Cherokees. The first one had me banging my head against the wall trying to figure out the problem. Came to realize after that the truck originally did not start and the customer had brought it to a shop where an aftermarket sensor was installed. Long story short, my cam/crank waveform was obviously fine as was the crank pattern itself to my eyes. "Guessing" that the aftermarket sensor was the culprit, I changed it with a dealer part and problem was solved. Only thing I can think of is the air gap may be different between it and the aftermarket part. Other than that, I have no idea what else would cause this.
I know right... I used to have an old diesel van (6.5L GMC vandura) that out of nowhere just died on me and went crank, no start. Turns out that theres a known issue with the pump driver that I learned later on in school one day... now I'm thinking that may have went out
Jeep 4.0L engines...oh man I keep a new crank sensor in my toolbox at all times for times like this. Happens more often than you think as they just...go if you'd use that term. This is one case where a parts cannon guess usually results in a fix.
programed tolerance of the wave form is to tight. a design flaw in the firmware. I had a 01 ford focus ZX3 zetec that the whole end plastic of the crank sensor had broke off so the coil was rattling loose and that caused a really wonky vibration at idle as the timing was wiggling around. no light no misfires.
Nice to see you do it my way sometimes! I do it because I'm certainly no pro, have no expensive analytic tools (but appreciate those who do!) and it's a constant weighing of paying for labor vs parts. I'd pay for the former if I got as much out of it as your customers do, Mr O...if there are any here in MN, commenters, let me know.
My 2003 Mitsubishi had this problem. If the light on the dash wasn't enough, an ECU algorithm would hunt through the cylinders one by one turning off fuel. So, I had a three cylinder car that felt like it was about to blow up. There was no help from Mitsubishi, you either drove it that way or lemon lawed the car. Later (read out of warranty) there was a TSB - bad transmission.
OEM crank sensors on Chrysler products is the only thing to use. We have done so many crank sensor jobs twice because we try to save the customer money with aftermarket first. We learned our lesson and only use OEM sensors now.
I've been chasing this same problem for a year. I have had 4 CPS installed during that time, and only when I finally got a Mopar part, was it resolved. The previous owner who swapped the engine in my wrangler, dropped one of the flywheel/torque converter bolts inside, it rode around in one of the grooves of the flywheel eventually hitting the CPS and breaking it (twice) before I discovered it. The CPS did continue to work while missing plastic! Eventually I discovered that issue, removed the bolt, and replaced the CPS with a Napa premium part. From day one that sensor always triggered the misfire code at 3000 rpm and above. I looked everywhere else assuming it was not related to the CPS. Now after seeing this video I went ahead and ordered a Mopar part and after 4 days the misfire code never happened. I can finally engine brake through the mountains around here without dreading the flashing misfire light. I watched this video during an international flight and then ordered the sensor as soon as I got home. Glad I have been subscribed to you for some time now.
Wow Never seen a Missfire On all 6 cylinders before And the Engine Run Smooth as Butter that is Interesting Defenitly looks like a Crank Sensor Failure good Video as Always Eric O great find on this video @SouthMainAutoRepairLLC
It's so good to have a lift, It was a full-on pain in the royal ass for me to install that sensor..kind of reminded me of that old school board game operation.
Thank you for the fix! I had the same problem with my 1998 Jeep Wrangler 4.0 . Only 3000 miles on a complete reman. longblock, ran like a top but the check engine light came on and I scanned it and the codes showed multiple misfires across all 6 cylinders. It still ran silky smooth. I ran across this thread yesterday and so I removed the newer aftermarket crank sensor and put in a used oem crank sensor I had laying around and it cured it. No more codes. Now I can get this Jeep smog tested tomorrow so I can get it re-registered. One thing I noticed is the magnetic tip on the OEM crank sensor is very strong and can pick up a wrench, but the aftermarket version can bearly pick up a screw. Thank you so much for sharing your technical knowledge, you saved me some money for sure!
I have a 98 4.0 With a new motor Also , I can’t get a oem cps so I put a hvwells one in and still has a misfire , she’s been in the shop for a few days , I hope they figure it out
TL;DR: The old sensor put out a good square wave pattern but was inaccurate/inconsistent in ON time. Thanks for the captures! I've never actually used a PicoScope before. I downloaded the software to look at your captures and gotta admit it's bloody cool. I was able to do measurements and analysis in about 5 minutes whereas it would have taken 20+ painstaking minutes with my Verus... So you can't compare times between old and new. You're not running at the same RPM so times are irrelevant. You have to compare degrees of crankshaft rotation as that's the only thing that is constant. I measured the width of 4 pulses on the crank pattern on both the old and new waveforms. I used the same tooth every time to be consistent. On the old sensor I got 1.427*, 1.575*, 1.562* and 1.579*. On the new waveform I got 1.16*, 1.16*, 1.109* and 1.111*. On the old sensor, each pulse lasted more degrees of crankshaft rotation than the new sensor. I imagine that's not what set the misfire. No two sensors are exactly the same so that would probably get processed by a crank relearn. HOWEVER... the pulses are pretty inconsistent on the old sensor whereas they are VERY consistent on the new sensor. The difference between the shortest pulse length and longest pulse length on the old sensor is 0.152 degrees. Even after going back through the new trace and looking at way more samples the largest difference I could find between pulse lengths was 0.011 degrees. That's going to be what's causing the reported misfire. The time delay between when the tone wheel notch passes by the old sensor and when the sensor is able to fully turn on and off its transistor just is not consistent.
Can't seem to download the Pico software - guess it's not compatible with the iMac. I hate Microsoft products ... but it looks like I'll need some for this kind of work. :( I don't consider that a "guess", since it's a known issue - you did what needed to be done, and everyone's happy. :)
The thought of installing Windows in a partition on my iMac sickens me, LOL! I'm afraid the bugs will come out and infect the rest of the system ... :D My brother has a Windows 10 laptop he's going to give me - that I can deal with. :)
You already said your answer. The computer sees a 200 microsecond difference and it is triggering a misfire. A method of detecting an engine malfunction such as a misfire includes determining engine speed values at each of a plurality of measurement angular positions, heterodyning the engine speed values with sine and cosine functions indexed in the angular domain, passing the heterodyned results through a low pass filter, and computing the resulting magnitude from the resulting two vectors. An apparatus for detecting an engine malfunction, such as a misfire, includes an engine speed analyzer, a multiplier, and a low pass filter. The (substantially instantaneous) engine speed values can be determined by measuring the time period between known angular displacements of the crank shaft/cam shaft and computing the speed value S=C/T where C is a conversion constant and T is the time between the (possibly fixed) angular crankshaft/camshaft displacement, for example as measured by a high resolution timer with microsecond or sub-microsecond precision.
Good job on getting a Mopar sensor. I had a 97 grand Cherokee 4.0 and I had a similar issue and I replaced the crank sensor with an aftermarket. It ran great for about a month then the same issue. I got a Mopar one and never had the issue again. I learned Jeep's are picky with sensors.
This reminds me of a scene from Star Trek IV (1986): Kirk : Mr. Spock, have you accounted for the variable mass of whales and water in your time re-entry program? Spock : Mr. Scott cannot give me exact figures, Admiral, so... I will make a guess. Kirk : A guess? You, Spock? That's extraordinary. Spock : [to Dr. McCoy] I don't think he understands. McCoy : No, Spock. He means that he feels safer about your guesses than most other people's facts. Spock : Then you're saying... [pause] Spock : It is a compliment? McCoy : It is. Spock : Ah. Then, I will try to make the best guess I can. McCoy : Please do.
Found this video after going thru the same thing on my 96 XJ, occasional high rpm check engine light with random misfire codes but it always ran smooth. Swapped the CPS sensor with OEM mopar and it seems to fix it so far. This video provided the needed confirmation :).
2500 RPMs is about 42 rotations per second. That's about 15,000 degrees per second (42 x 360). 200 microseconds (0.0002 seconds) is a difference of about 3 degrees rotation.
The problem is using AFTER MARKET SENSORS, PERIOD, IT'S A CRAP SHOOT WHEN USING THEM. Either bite the bullet & buy from dealer or go to pick a pull, junkyard & get a few. Make sure their original equipment. EDUCATED GUESS NOT JUST A RANDOM THROW PARTS AT IT GUESS BIG DIFFERENCE SMA, GREAT JOB AS ALWAYS.
please help me s m auto!!!!!i have 2000 neon 66k it missing bad at 22-2500 rpm ,it has new timing belt kit,pplugs wires coil,new tps sensor,it runs great at any rpm until i under load at 2500rpm but above n its fine?no money light exept occasionaly if u stay on pedal n force it at that throttlr position money light falshes n bell dings,but no codes no check engine light?????it did throw code once it was evap,misfire cyl 1, but they have been off for months.when i put car in reverse it sputters really bad also.im lost i cant afford to keep guessing n ive had it to two places n they cant figure it out,today it money lite flashed n bell dang for good mile i was on interstate n had to stay moving.im so sad n dissheartened over this i go to kidney diaylasis n have no family or anyway to get there i NEED MY CAR MY LIFE DEPENDS ON IT!!!!PLEASE HELP IM FROM PA I WILL COME THERE I WANT IT FIXED!!!!!!!!I can go great on highway as long as my rpm is above 2500 n i dont have any long hills to get up to speed on.i just put tps sensor on yestetday that did nothing but break my wallet $65.if it was my cat wouldnt it do it all time n not let me get up to 3rpm???(thats crusing at 70mph on i -80.)my phone is 814-648-8534 email pstancliffe76@gmail.com,please any ideas n will u work on it i will drive to ny i KNOW U CAN FIX IT i watch all your videos am big fan,please help
2001 GC with lots of pissy-little-'minor'-tooling-around-getting-it-right-things-that-annoy-me-so-it-doesn't-let-me-down-&-I-know-things-are-right-issues. They're not bad vehicles, just vehicles that need maintenance! Liked & subscribed! TYVM for an informative channel. O2 sensors are another red headed stepchild for these as well as clean battery terminals. I've seen on a few occasions these Jeeps are fussy about very clean voltage & copper core spark plugs. No better plugs for them.
I had a similar symptom with a Honda accord. Misfire that got incrementally worse over a years time. Did all the checks, diagnosed it as a bad exhaust valve. Put a head on it (correct diagnosis, the exhaust valve had part of it eroded away in a neat little perfectly round pac man-esque bite). The similarity was when it was done it ran flawlessly. At RPM above 1000 it would flash the money light and set a misfire code, but it was running perfect (as a honda can). For 2 days it drove me nuts, had to walk away and do other payers as i contemplated this bizarre turn of events. The supervising super tech at the company did all the same tests i did, called tech support. No dice. I started exploring EVERY possible data parameter. As i stumbled through every possible menu in the scanner looking for ANYTHING that could help, i find an option buried in the engine side (Snap on scanner) "reset engine adaptives". CLICK!. THE PROBLEM WAS GONE. I was thinking it was something like that on Eric O's headache. First time i had ever seen that as a menu option.
I was a computer tech in the navy. Our Crypto computer went down. Replacement part on the other side of the world. We were left on our own until part could arrive in the middle of the Persian Gulf. So....I broke out the Motorola IC Chip schematics of what parts this IC chip took the place of and built the part on a cardboard box. IT WORKED! We were back online with the crutch i made from parts. All kinds of resistors diodes and zener diodes (adjustable) power and so forth. What am I getting at you say???? After market parts like the one you replaced may have been made with the same parts but not the same quality parts. ie: resistors with +-5 or 10% diodes with flakey electronic back flow construction. These cheaper made parts do not perform with the tight tolerances of OEM parts. That's why you can buy them at a lower cost. It seems to me your guess work (experience) is more valuable than you take credit for. Nice job. I think the question or problem lies in the construction of the part.
Some Engine computers are probably so sensitive, that if they pick up small anomalies, or slightly off-time feedback events from aftermarket electronic parts, that it triggers the check engine light, and limps the car. That happened to me with an ‘02 Toyota Camry spark plug coil. The original coil was replaced with a China made aftermarket turd coil, because it wasn’t firing #2 cylinder, and I was a broke joke back in 2009. It worked well for about 2 months, then the check engine light came on. This time it was a PO302 (Igniter malfunction code), and a limpy car that would shut off if you accelerated too hard on the road. I suspected that the China made coil was culprit, and bought some used original Denso coils from the junk yard, and replaced it. Problem solved. No check engine light, and No more limp. Never buy aftermarket electronic parts for newer vehicles!!!! Buy original.
13:25 OMG YOU DIDNT TORQUE IT! . ya, and its not going to be.... unless you pay me to pull the motor no way to get a torque wrench in their (u joints sure, but 20 foot pounds at the wrench is NOT 20 at the socket)
I looked at the wave form and took measurement of the time it takes the sensor to go down to 0v after hitting its 5v the the old one it took 905ns and on the new one it took 405ns and did you measure the resistance of both ckp sensor sorry i suck at explaining
The overall duty cycle is 7% less for old sensor. I would say that the old one started to drop down earlier and trailing edge time was longer. Depending what voltage ECM interprets as zero, the difference will be more than 7%.
I know three retired Chrysler engineers who were very familiar with the JTEC PCM. While all generally praised it, the word around Auburn Hills was that JTEC was an abbreviation for "jus' tryin' to be an engine controller". I wouldn't be surprised to find a line of code someplace that checked for Brand X parts!
I have a 2001 Wrangler 4.0L with the same symptoms. CEL comes on at about 3500 rpm under load or sometimes during light deceleration at highway speeds. But, no misfire is felt and engine power feels good. The crank position sensor has been replaced with OEM part several times. Problem still there. Two local shops have used their parts cannons on it. Problem still there. Last shop suggested replacing the ECM. I'm still thinking about it but don't want to pull the trigger until it can be verified. I need to find a good shop in the Albuquerque area that can do a real diagnosis (lab scope, pressure transducers, etc) and verify before hanging parts.
I'm no rocket surgeon but I believe that based upon the data provided that the magnetic response from the old"aftermarket" sensor has lost its effectiveness. That means the magnet wore out. Good parts mean long term results. Bad "aftermarket" parts only last for a short term fix.
Couple years back, a Duralast crank sensor i put on my personal 96 Cherokee left me chasing the tail of an invisible ghost which killed my entire weekend and it was the only 2 days I had off every 45 days. It showed up on a SnapOn scope and a multimeter as working fine hot or cold so I completely wrote it off in my head. Dug through EVERYTHING else, even the ECM software... eventually I took a chance a went and swapped it out at Autozone, and it fixed it!!! ...... for another month. Then the same shit happened. Replaced a second time under warranty, got another 6 or 7 weeks out of it... took it back to Autozone, got the manager to refund my money, went to the local Jeep dealer and dropped the added price on a factory sensor. Never had another problem for the remaining 3 years.
So why does my 95 4.0l idle at about 250 rpm. Cold idle is at 750 rpm. It will sometimes hang for a second at 750 after being revved up, but not always. IAC has been cleaned and wasn't even dirty to begin with. No codes, but being a 95, its barely got a check engine light. For idling so low, it does a good job, not as rumbly as I would expect, and never dies. Recently it has gotten closer to stalling, but it bounces back. The engine seems to be very strong and not lacking any power. New fuel pump and filter, ignition set. I'm suspecting a sensor, but I'm not finding anything to lead me in any direction. I'm not trying to replace everything under the hood, although I'm getting close with this being a 22 year old Jeep.
Crank sensor ... bet $ it's aftermarket Mine misses at idle slightly, new EVERYTHING, give it a little gas and brake and smooth as glass, pass a slowpoke on the hwy and hit 4k rpms (all the cammed 4.6 needs to walk it in a hurry) flashing light but no miss.. just don't want to buy another sensor ☹
Just changed my crank sensor today (Mopar OEM). I strongly recommend taking five minutes to drop the driveshaft at the differential. I swung it over toward the passenger side and ziptied it to the catalytic convertor. I was then able to gain much better access to the sensor bolts. I only had to use one extension and a wobble joint and was actually able to reach around the exhaust and get both hands up into the area to start the bolts when reinstalling. I still had to work by feel but it was much easier than fighting the driveshaft. I hope this helps those of you facing this repair.
The Mopar Crank sensor using a specific code and pulse to communicate with the PCM (think of it like to encrypted phones taking to each other). The aftermarket ones are close but not enough to be registered 100% with the PCM. So there Crank sensor is saying "We're all good dawg" but the PCM is only recieving "We'r al d daw." Some are so off they won't even start even though the scope looks good. Just wanted to add if you have to but aftermarket sensors the ones that will give you little to no trouble is Standard Motor Products. This goes for ALL MOPARS. A few of us guys on the forums fingered out why they didn't work when we were watching the programming in the PCM itself.
Thanks again @South Main Auto Repair for fixing my Cherokee! The 4.0 ran smooth as silk driving back to PA, no money light! Wife says I should keep it now that you fixed it... LOL
rtchrg440 sell it a run, run fast. I have been a Jeep owner for over 20 years...and still own two in the Family. I swear those vehicles are designed to make money for the Chrysler company in parts sales AFTER the initial vehicle sale.
I know what you mean. I was a faithful Toyota owner before I bought this XJ, never had a vehicle like this that always seems to need a part every other month. One thing I will say, I usually buy aftermarket parts for the Jeep to save money, and at least 50% of the time the part has failed in a year. So I really bought the part twice, and probably didn't save in the long run. Frustrating! This crank sensor was aftermarket (either from RockAuto or AutoZone, can't remember), and it was doing this from the beginning. I shot a ton of other parts at this Jeep thinking it was a legit misfire.
rtchrg440 I only go OEM for my Jeeps either new or the used parts market - from junkyards - that has recently and robustly sprung up on the internet in the last few years like partsmarket. Mopar rear drive shaft new $895, from the salvage yard $65 plus $50 for shipping and I can get one from States not in the rust belt. I tried the Chinese made parts once. Part was a rear window strut that holds up the window. Lasted 18 months. Then I purchased Mopar OEM and it so far has lasted 4 years.
rtchrg440 nice Jeep! I have a 2k XJ myself and I love it. I have the OEM sensor and after this video I might swap it in, got that tiny flutter going on but no money light. Have a great weekend.
stinking "aftermarket junk". as eric and many of us say.
What an odd and annoying fault because it is so indecisive. As someone else mentioned, the transient spikes after the new sensor were fitted seemed lower, so maybe it was just a connection resistance issue or the new sensor might have a low value capacitor in it as a filter. It could possibly be one of those things that didn't occur when they were writing the software, but as age crept in it became an issue. There are some industrial control systems where you have to use a specific brand of contactor because the auxiliary contact closure timing is so critical that the software shuts off the machine and flags it as a contactor fault if the wrong brand of contactor is used.
It's really annoying when the timing isn't critical to the job the machine is doing, it's just critical to the time that was programmed. Programmers set it up to see a value in a very short time like .002 seconds when it wouldn't matter if it took 5 seconds.
@@tiredoldmechanic1791 The rise/fall time on the aftermarket sensor most likely is causing the computer to get confused as it's not seeing a sharp transition to measure rotational acceleration. This allows it to run but not monitor itself. I suspect the "square" edge of the signal starts to round over. The programmer needs something consistent to trigger off to accurately measure acceleration. If we only cared about rpms I would agree that it's the programmer's fault. I'm a hardware guy and like to blame software too but this time it is not the programmer's fault. This suspected rounding (rc effect) is only visible if zoomed in. Then again I could be wrong as the data from the video is zoomed out way too far.
Shit up Engineer.
Electronics are fickle things... It's almost like programmers don't give enough leeway for things as they age. But, it is what it is I suppose
I have shot part at a car a few times and that's was the problem fixed😂
Noooooo that’s a cherokee..... you can’t wear a jeep hat and get that wrong!!
I remember a story where a huge diesel motor on a giant cruse ship wouldn't run. None of the technicians could figure out why. They gave up and called in an old retired dude. He looked at a while. Pulled a large hammer out a bag and gave it a hard WACK! It Stared up and ran perfectly. When he gave them the Bill it was for $10,000.00. They all freaked. "you didn't do anything" they said. Give us an itemized billing statement! The bill he produced said. One hammer blow: $8.99 Knowing where to hit: $9,991.01
Dj Quack lmao that made my day
I love it!!!
"knowing where to hit" is ABSOLUTELY RIGHT! In so many cases we have to draw from our experiences, Eric knew which part to change and the old man knew where to hit. 1 + 1 is 2 because my 1st grade teacher taught me so. NEXT!
I saw the video that story came from, definitely priceless!
Eric I was wondering on that crank sensor do you think that the aftermarket sensor is a different kind of sensor then the OEM I know there are two different kind of sensors. One can be hall effect sensor and honestly I am not remembering the other type of sensor. Just a thought
The Jeep obviously noticed your hat and you meant business...no frickin around
Will s And that's a REAL JEEP! Not one of those Fiat based monstrosities.
Lol... You won the comments..lol
Key word here is EDUCATED guess, there is a difference vs just a wild guess!
SWAG vs pure wild guess....
Difference being no beard strokeing
Indeed
Ssshhhhhhh it was not a guess it was hypothesis, theory, prediction sorted!!!!!
bodgit and leggit garage a
A
It is one thing to shoot parts at it when nothing shows wrong but another to look up data talk to others and then take an educated guess very well done.
When I trained as a tech in the military we had a W.A.G. and a S.W.A.G. Wild assed guess or a scientific wild assed guess. ;) This was one of the later. I know, old video, but I enjoy watching them when they pop up in my feed.
Nice video on using what I teach as "educated guessing". Your video example is "NEEDED" is the "toolbox" of technicians or DIY wrench turners. In the real world sometimes things just don't make sense. Theres no visual or measurable evidence to go from and to fix the problem we turn to what I call "the medical method"....This is where you consider what worked for a 100 other people get healed and go for it. There is still much thought and consideration put into this decision based on research, peers and OEM support. Just reminds me how glad I am to be a technician most often working from pure evidence and not "practicing medicine"! Once agian, great job and I bet you would like my "Every Mechanic Should know This" Playlist. I'm a fan of South Main Auto videos for sure....Coach Conley
Shane Conley yet another example of ‘it works in practice, but does it work on paper?’
That feeling us mechanics get when shit goes right
Sorry, "when shit goes right" is an alien terminology. Words that dont live together peacefully in my world. LIke oil and water in the crank case. :-)
Hi Eric. Downloaded the files @2500 rpm and used Pico measument tools. Old sensor duty cycle is 10,28% New is 11,1%. 7% difference in pulse width -> upto 25 degree variation to angle speed dRpm. Old sensor became more insensitive detecting a flywheel teeth. Turned on later and turned off a earlier. Could this be the diagnosis?
Janne Pohjala That’s what I found as well. The duty cycle obviously didn’t affect engine operation but the PCM was sensitive to it.
Awesome! I wonder if the magnet on the crank starter wheel gets weaker with time and heat, thus the heavier wound and more sensitive mopar sensor is the only one accurate enough?
Where are the files I looked for them couldn't find them
Thats what I thought. That maybe the aftermarket sensor is manufactured slightly differently that maybe the PCM wasn't getting the full value it was expecting.
When it comes to crank/cam sensors I learned a long time (the hard way)ago to only use OEM.
Those 4.0's love Mopar sensors only.
Ben R Fords also.
Add Gm fuel pumps only & MAF sensors on GM cars. Been burned too often with non OEM parts. Cost more, but I only want to do it once. Especially dropping the tank for a fuel pump replacement
If you can guess, I can guess, I guess.
Your just guessing Jim
Once again, experience, and knowledge of the trade, wins over a stubborn vehicle.
Had a 2000 Chrysler Sebring with the 2.5l V6. The engine would just die for no reason. Driving, at a stop or just idling, the engine would just die. At times, it would restart. At other times, it would take some time before the engine would fire up. No C/E light, no codes. Checked the crank sensor, it checked good. Wiring checked good. Everything checked good. I heard a similar thing of where the crank sensor would cause the engine to die. I replaced the crank sensor and all was fixed. Could be that the sensor was on its way out.
Hi Eric, very interesting case, I downloaded the waveforms and the only difference I could find was that the old sensor at idle and 2500 rpms the square signals from crank were longer time base wise idle= 697 us Old to idle= 472 us new at 2500 rpms old =216.9 us new= 133.3 us. Would that be enough to create false misfires counters?
Yeah the waveform plateau length seems to be the only difference
It would be easier perhaps if it was synced to the "missfiring cylinder" before and after
MrBorntoroll the thing here is that there was no actual misfires, so this is more of a software glitch than an actual misfire. All cylinders showed misfire only on software.
I mean with the firing event we would have some more measurments as the pcm measures speed of the crankshaft after cyllinder firing to flag a missfire.
Ok. We kinda have spark events. The theory: if PCM counts time of crank rotation after spark event not until every next HIGH hump but until next for ex "big low gap and HIGH hump" (to give time for combustion to occur) then we can see that with old sensor be get quite bigger (in ms) time delay which can be calculated as missfire if PCM wants to see shorter time. The bad news: the theory doesn't work during idle.
Eric.....what's the chances the old crank sencor was a little loose or holes bigger then the bolts and causing vibration issues?...ran into that once b4...
It needs 5 more "ignition tune ups" and about 11 bottles of fuel system cleaner, then keep telling the customer it's bad gas if he comes back.
most people say "i dont know" when asked when was the last time spark plugs were done (and on this....people forget the cap and rotor is a wear part)
so i usually will pull a plug to have a gander
.
but ya.... ive shotgunned my own cars ignition (dont have time, and dont want to WORK on my own shitboxes)
99 GM 3.1...... waste spark can go F it self
.
new plugs and wires.... still had a soft miss that the CEL didnt light for
but the old plugs WERE quite old, and the wires 10 years old....
.
turned out..... bad coil
then i tightened the bolt too much because it was -30f....
and cracked that coil
.
then i got a bad coil..... that split in half
turned my car into a 4 banger..... limped my way into work
.
and finally..... ive had NO issues for 80,000 miles
and now its about time to do the plugs again...
.
PS
on my 97 4.0 jeep..... i have a miss that cant be felt (some times cly 5, some times random multi, or sometimes 2 5 and random)
but its usually going down a hill, with like 2 gallons of gas in the tank....
.
throws the code with in 200 feet of the same hill.....
.
doesnt seem to do it (as often) when it has 1/4+ tank of gas
.
oh well..... its a mopar..... reset the code, keep driving till something changes / gets worse enough to fix
I don't think there is any shame in guessing if you can draw a logical line thru it. I mean don't get me wrong... charge him double still. :-)
Had the same issue on my 2000 Grand Cherokee and replaced the same sensor with OEM and it fixed it that was 2 years ago
Had a similar situation. Friend took his 4.0 Cherokee into the shop because of check engine light
at highway speeds. Shop said it was indicating all 6 cylinders were showing a "spark" miss and
they began replacing parts. ECM and Coil Pack and other parts to the tune of over
$2650.00 in parts My friend asked if I could check with the shop and so I called just casually
asked what waveform they were getting generated when they tested They said it was great and
had never showed a bad waveform and that was what throwing their troubleshooting off.
I quietly suggested that they might try changing the crankshaft sensor ( which they had not
done to this point. It is not my vehicle or my right to get into the middle of the problem).
Long story short, they changed the crank sensor and the wave forms returned to normal.
Sadly, of course they just added the cost of the crank sensor to the $2650.00 parts plus
labor bill telling my friend that somehow the "ECM had defaulted in it's code and caused other
parts such as the coil pack and crankshaft sensor to fail". I explained to my friend that such thing
just could not happen and if he wanted to dispute the charges I would be willing to help him but
he would need to start the process not me. He never did anything about it so he received
an education, I received an education and I am sure the shop received an education.
Aloha from Maui
Randy Gentry I guess malpractice insurance won the lottery that day🍾
So, what is the ethical way to run through this parts changing fusillade, short of bringing it to Eric "the Swami" @ SMA ? I got $9,899.00 hammers too, but feel bad using them.
Looks like you need EricTheCarGuy to come weld that cylinder head back on your Honda so you can get your bay back.
another awesome video by Eric O....looks like your parts cannon has some serious experience to get it right on the first try...
some serious aim on thats parts cannon... Laser scope i think.
I WAS having same problem but I change crank cam and maf the problem was fixed but I have no idea until thus video was released how I fixed that jeep
Another excellent video from SMA. Thanks and look for some family ice cream $$ in your PayPal account.
My thoughts on the misfire counters and DTC - the diagnostic calibrator(s) for the components and misfire DTCs for obvious reasons use new OEM parts and 6 SIGMA calculations base on data to establish failure thresholds.
It maybe the replaced (aftermarket?) part slowly drifted out of specs, resulting in misfire counters climbing and the DTC setting. The component failure DTC 'should' have caught the drift, but that's a tough one to catch.
awesome diagnosis and work. I actually did one of these jobs while I was in a high school auto shop class! of course, My school didn't have any real awesome scope software or anything. After WEEKS of testing with a DVOM, I had isolated the crankshaft sensor, and replaced it and verified the fix. My shop teacher was super impressed with me. I owe all my success to the man.
Parts cannon for the WIN! I blame it on the Chinesium ;)
farmboy30117 AVE! FTW. I think ScannerDanner has talked out aftermarket vs OEM sensors in the past.
Agreed. Back pickup. Inconsistent.
On the 4.0 these things (CS) go bad intermittently ... usually a thermal breakdown causing "no start" ... stars after cooling down ... cheap repair (but use an OEM one)
An experienced based guess is what people pay you for! Your knowledge is valuable!
Recently replaced a 4.3 engine. Got a P0300 code when holding down throttle over 2000rpm. Money light flashes says cylinder 1 and 4 are misfiring. Can't feel any misfire in engine. Could it need a crank relearn? And if so, what scanners can do a crank relearn? Thanks...
Having same issue with a 01 Jeep Wrangler at the shop. At 3K RPM shows ghost misfires. I put an aftermarket sensor and didn't help, guess ill go OEM. I noticed you didn't relearn the misfire counter when installing the new crank sensor. You can see and your scanner it says adaptive learned no. That's why it wasn't showing misfires. I know because when I changed the crank sensor it wasn't misfiring again until it learned the misfire monitor. You fixed it though since the vehicle never returned.
Jeeps do not like non-OEM sensors. It's just that simple. I know this from experience on a 2007 Jeep GC 5.7l. Go to the dealer and pay the man for the Mopar part. It's better that 3 trips to Advance (Buy the part, exchange the part that didn't work, refund the part)and then one to Jeep .
Scott Berger
I own a 2001 Chrysler Sebring convertible LXI, needed to replace the engine as a rod had come through the block by my soninlaw. It wouldn't give a green light to pass emissions so I took it to the dealer for an inspection sticker. What I got was no sticker and 14 pages printed out with defects. Upper and lower ball joints were bad and a whole host of problems. All four yeah four O2 sensors needed to be replaced again because he didn't know Chrysler products require factory O2 sensors to work properly. After replacing the last O2 sensor the scanner finally lights up green light. Dealer wanted $2897.41 to fix and give the car a sticker. Cost me just over $1200.00 to fix everything. Using an old school mechanic at his own shop. Took over 6 months as I was on a budget. The wife's idea of maintenance is put gas in it and stick the key in it. That was 5 years ago, just finished replacing the oil seals between the engine and transmission.$ quote was $600 actual cost just under a K. Both engine mounts needed replacing, massive aluminum mounts. The rubber had broken through on both of them. What's left? Drivers door motor and right rear window motor then everything will work as intended.
Ahhh. The pleasures of vehicle ownership when your wife refuses to listen to my advice. I lost her last year after a medical issue.
Now finally in another month I will have the car back to factory specifications.
After seeing what you went through replacing a window motor I think I'll include the regulator with the motor on the drivers door.
Cheers!
My 02 wrangler 4.0 had the same problem. Found out that the sensor has a felt pad on it you need to mash it into the flywheel and it wipes the felt off. The oem came with instalation instructions saying to do it, reinstalled the aftermarket one mashing it in and worked perfectly, couldn't find anything anywhere online to help.
My Grand Cherokee 4.0L did the same thing and it was the Crank Positing Sensor. These 4.0L Straight 6 are noted for these.
I've found that gut and others experiences have bettered the high priced scanners alot of the time most customers do not understand the scanner jargon great video Eric O
Last weekend there were so many reaching around thanks to a camaro, it caused record bruising and burns. The classic isn't supposed to do that.
Nice Quiet Riot reference.
From an electronics point of view, I can't find the specs for the picoscope, but I suspect that the aftermarket ckp is producing noise on the signal line that is too fast for the Pico to catch. Next time I get one of these in the shop I'm going to use a 200mHz scope on it and see what there is to see. Maybe it's nothing but, that sensor HAS to be producing something the ECM doesn't like. We just have to find it.
I would take your best guess over most mechanics fact. like kirk taking a guess from spock....lol
I have seen this on multiple Cherokees. The first one had me banging my head against the wall trying to figure out the problem. Came to realize after that the truck originally did not start and the customer had brought it to a shop where an aftermarket sensor was installed. Long story short, my cam/crank waveform was obviously fine as was the crank pattern itself to my eyes. "Guessing" that the aftermarket sensor was the culprit, I changed it with a dealer part and problem was solved. Only thing I can think of is the air gap may be different between it and the aftermarket part. Other than that, I have no idea what else would cause this.
Had the same Jeep. Same issue except it would die completely. Sucks to think that would’ve fixed it. Wish I kept it.
I know right... I used to have an old diesel van (6.5L GMC vandura) that out of nowhere just died on me and went crank, no start. Turns out that theres a known issue with the pump driver that I learned later on in school one day... now I'm thinking that may have went out
Arr man the parts cannon ye scurvy dogs
Well done Eric, yet another satisfied customer brought in by You Tube. Great video!!
Could this be the issue on an 04 2.7l dodge? I keep getting cylinder 3 misfire. Changed the plug and coil pack and still getting it. Runs fine though.
Jeep 4.0L engines...oh man I keep a new crank sensor in my toolbox at all times for times like this. Happens more often than you think as they just...go if you'd use that term. This is one case where a parts cannon guess usually results in a fix.
programed tolerance of the wave form is to tight. a design flaw in the firmware.
I had a 01 ford focus ZX3 zetec that the whole end plastic of the crank sensor had broke off so the coil was rattling loose and that caused a really wonky vibration at idle as the timing was wiggling around. no light no misfires.
Nice to see you do it my way sometimes! I do it because I'm certainly no pro, have no expensive analytic tools (but appreciate those who do!) and it's a constant weighing of paying for labor vs parts. I'd pay for the former if I got as much out of it as your customers do, Mr O...if there are any here in MN, commenters, let me know.
My 2003 Mitsubishi had this problem. If the light on the dash wasn't enough, an ECU algorithm would hunt through the cylinders one by one turning off fuel. So, I had a three cylinder car that felt like it was about to blow up. There was no help from Mitsubishi, you either drove it that way or lemon lawed the car. Later (read out of warranty) there was a TSB - bad transmission.
Never thumb-wrestle with someone that has thumbs @15:57 this large.
That Jeep is mint!
Won't last long with Pennsylvania winters
Like more cowbell, more brake clean please. lol
owned a Cherokee for almost 20 yrs.; crank position sensors were iffy if replaced, solved problem by going to dealer & using factory one.
OEM crank sensors on Chrysler products is the only thing to use. We have done so many crank sensor jobs twice because we try to save the customer money with aftermarket first. We learned our lesson and only use OEM sensors now.
Eric, we used to call that a SWAG. Scientific Wild Ass Guess. Haha
I don’t think that Jeep liked aftermarket parts. Either that or it was aliens...
Sometimes the old EPG and your gut work well together. Another Victory!
I've been chasing this same problem for a year. I have had 4 CPS installed during that time, and only when I finally got a Mopar part, was it resolved. The previous owner who swapped the engine in my wrangler, dropped one of the flywheel/torque converter bolts inside, it rode around in one of the grooves of the flywheel eventually hitting the CPS and breaking it (twice) before I discovered it. The CPS did continue to work while missing plastic! Eventually I discovered that issue, removed the bolt, and replaced the CPS with a Napa premium part. From day one that sensor always triggered the misfire code at 3000 rpm and above. I looked everywhere else assuming it was not related to the CPS. Now after seeing this video I went ahead and ordered a Mopar part and after 4 days the misfire code never happened. I can finally engine brake through the mountains around here without dreading the flashing misfire light. I watched this video during an international flight and then ordered the sensor as soon as I got home. Glad I have been subscribed to you for some time now.
just for the diy from old tech.if you see 9.8 or 10.8 on the head of the bolt it is metric.
Wow Never seen a Missfire On all 6 cylinders before And the Engine Run Smooth as Butter that is Interesting Defenitly looks like a Crank Sensor Failure good Video as Always Eric O great find on this video @SouthMainAutoRepairLLC
Engine light on with a long Crank 96 jeep Cherokee
It's so good to have a lift, It was a full-on pain in the royal ass for me to install that sensor..kind of reminded me of that old school board game operation.
I also had to undo the transfer case driveshaft.
Jeeze, the engine bay is clean on that old Jeepster. He must be crazy.
Just bought myself a parts cannon and am feelin good !
You don't have to buy them. They give them away for free at Autozone and Advance. The ammo for them can get expensive though.
Lol
Eric, I like how informative your videos are, plus I like when I hear that you help out other channels with their diagnosis ( Will R.A.) COOL
Aftermarket sensors with mopar cause more problems then there worth!
Thank you for the fix! I had the same problem with my 1998 Jeep Wrangler 4.0 . Only 3000 miles on a complete reman. longblock, ran like a top but the check engine light came on and I scanned it and the codes showed multiple misfires across all 6 cylinders. It still ran silky smooth. I ran across this thread yesterday and so I removed the newer aftermarket crank sensor and put in a used oem crank sensor I had laying around and it cured it. No more codes. Now I can get this Jeep smog tested tomorrow so I can get it re-registered. One thing I noticed is the magnetic tip on the OEM crank sensor is very strong and can pick up a wrench, but the aftermarket version can bearly pick up a screw. Thank you so much for sharing your technical knowledge, you saved me some money for sure!
I have a 98 4.0
With a new motor Also , I can’t get a oem cps so I put a hvwells one in and still has a misfire , she’s been in the shop for a few days , I hope they figure it out
TL;DR: The old sensor put out a good square wave pattern but was inaccurate/inconsistent in ON time.
Thanks for the captures! I've never actually used a PicoScope before. I downloaded the software to look at your captures and gotta admit it's bloody cool. I was able to do measurements and analysis in about 5 minutes whereas it would have taken 20+ painstaking minutes with my Verus...
So you can't compare times between old and new. You're not running at the same RPM so times are irrelevant. You have to compare degrees of crankshaft rotation as that's the only thing that is constant. I measured the width of 4 pulses on the crank pattern on both the old and new waveforms. I used the same tooth every time to be consistent. On the old sensor I got 1.427*, 1.575*, 1.562* and 1.579*. On the new waveform I got 1.16*, 1.16*, 1.109* and 1.111*.
On the old sensor, each pulse lasted more degrees of crankshaft rotation than the new sensor. I imagine that's not what set the misfire. No two sensors are exactly the same so that would probably get processed by a crank relearn. HOWEVER... the pulses are pretty inconsistent on the old sensor whereas they are VERY consistent on the new sensor. The difference between the shortest pulse length and longest pulse length on the old sensor is 0.152 degrees. Even after going back through the new trace and looking at way more samples the largest difference I could find between pulse lengths was 0.011 degrees. That's going to be what's causing the reported misfire.
The time delay between when the tone wheel notch passes by the old sensor and when the sensor is able to fully turn on and off its transistor just is not consistent.
Can't seem to download the Pico software - guess it's not compatible with the iMac. I hate Microsoft products ... but it looks like I'll need some for this kind of work. :(
I don't consider that a "guess", since it's a known issue - you did what needed to be done, and everyone's happy. :)
Did you try this latest OS X version of the Pico SW?
www.picotech.com/downloads
Check out Parallels
The thought of installing Windows in a partition on my iMac sickens me, LOL! I'm afraid the bugs will come out and infect the rest of the system ... :D
My brother has a Windows 10 laptop he's going to give me - that I can deal with. :)
To each their own :). I was skeptical too but it makes life a lot easier and no trouble so far.
If anything goes weird with an old 4.0 it seems it's almost always because of the crank sensor. Full time Jeep parent here.
You already said your answer. The computer sees a 200 microsecond difference and it is triggering a misfire. A method of detecting an engine malfunction such as a misfire includes determining engine speed values at each of a plurality of measurement angular positions, heterodyning the engine speed values with sine and cosine functions indexed in the angular domain, passing the heterodyned results through a low pass filter, and computing the resulting magnitude from the resulting two vectors. An apparatus for detecting an engine malfunction, such as a misfire, includes an engine speed analyzer, a multiplier, and a low pass filter. The (substantially instantaneous) engine speed values can be determined by measuring the time period between known angular displacements of the crank shaft/cam shaft and computing the speed value S=C/T where C is a conversion constant and T is the time between the (possibly fixed) angular crankshaft/camshaft displacement, for example as measured by a high resolution timer with microsecond or sub-microsecond precision.
secret code: BrakeClean with caps on the B and C, I heard the click queue.
the old one is probably a dorman one, or a bwd!
Gives you the right to wear that cap with a jeep in the shop lol .
cool to have a vid on a saturday too, have a day off tomorrow lol .
Wow your parts cannon is damn accurate, Eric! Who needs a labscope? ;)
Guess don't test!
Nice Quiet Riot quote... apart from being a great technician,,, you also have good taste in music!!!
Will have to remember this fix! I have the exact same jeep with 193k on the clock and counting, been the best vehicle I have ever owned.
He sure keeps that old Jeep clean! Well done, Dr. O!
Good job on getting a Mopar sensor. I had a 97 grand Cherokee 4.0 and I had a similar issue and I replaced the crank sensor with an aftermarket. It ran great for about a month then the same issue. I got a Mopar one and never had the issue again. I learned Jeep's are picky with sensors.
This reminds me of a scene from Star Trek IV (1986):
Kirk : Mr. Spock, have you accounted for the variable mass of whales and water in your time re-entry program?
Spock : Mr. Scott cannot give me exact figures, Admiral, so... I will make a guess.
Kirk : A guess? You, Spock? That's extraordinary.
Spock : [to Dr. McCoy] I don't think he understands.
McCoy : No, Spock. He means that he feels safer about your guesses than most other people's facts.
Spock : Then you're saying...
[pause]
Spock : It is a compliment?
McCoy : It is.
Spock : Ah. Then, I will try to make the best guess I can.
McCoy : Please do.
Found this video after going thru the same thing on my 96 XJ, occasional high rpm check engine light with random misfire codes but it always ran smooth. Swapped the CPS sensor with OEM mopar and it seems to fix it so far. This video provided the needed confirmation :).
That’s a real Jeep, not a grand lol
2500 RPMs is about 42 rotations per second. That's about 15,000 degrees per second (42 x 360). 200 microseconds (0.0002 seconds) is a difference of about 3 degrees rotation.
The problem is using AFTER MARKET SENSORS, PERIOD, IT'S A CRAP SHOOT WHEN USING THEM. Either bite the bullet & buy from dealer or go to pick a pull, junkyard & get a few. Make sure their original equipment. EDUCATED GUESS NOT JUST A RANDOM THROW PARTS AT IT GUESS BIG DIFFERENCE SMA, GREAT JOB AS ALWAYS.
please help me s m auto!!!!!i have 2000 neon 66k it missing bad at 22-2500 rpm ,it has new timing belt kit,pplugs wires coil,new tps sensor,it runs great at any rpm until i under load at 2500rpm but above n its fine?no money light exept occasionaly if u stay on pedal n force it at that throttlr position money light falshes n bell dings,but no codes no check engine light?????it did throw code once it was evap,misfire cyl 1, but they have been off for months.when i put car in reverse it sputters really bad also.im lost i cant afford to keep guessing n ive had it to two places n they cant figure it out,today it money lite flashed n bell dang for good mile i was on interstate n had to stay moving.im so sad n dissheartened over this i go to kidney diaylasis n have no family or anyway to get there i NEED MY CAR
MY LIFE DEPENDS ON IT!!!!PLEASE HELP IM FROM PA I WILL COME THERE I WANT IT FIXED!!!!!!!!I can go great on highway as long as my rpm is above 2500 n i dont have any long hills to get up to speed on.i just put tps sensor on yestetday that did nothing but break my wallet $65.if it was my cat wouldnt it do it all time n not let me get up to 3rpm???(thats crusing at 70mph on i -80.)my phone is 814-648-8534 email pstancliffe76@gmail.com,please any ideas n will u work on it i will drive to ny i KNOW U CAN FIX IT i watch all your videos am big fan,please help
2001 GC with lots of pissy-little-'minor'-tooling-around-getting-it-right-things-that-annoy-me-so-it-doesn't-let-me-down-&-I-know-things-are-right-issues. They're not bad vehicles, just vehicles that need maintenance!
Liked & subscribed! TYVM for an informative channel.
O2 sensors are another red headed stepchild for these as well as clean battery terminals. I've seen on a few occasions these Jeeps are fussy about very clean voltage & copper core spark plugs. No better plugs for them.
I had a similar symptom with a Honda accord. Misfire that got incrementally worse over a years time. Did all the checks, diagnosed it as a bad exhaust valve. Put a head on it (correct diagnosis, the exhaust valve had part of it eroded away in a neat little perfectly round pac man-esque bite). The similarity was when it was done it ran flawlessly. At RPM above 1000 it would flash the money light and set a misfire code, but it was running perfect (as a honda can). For 2 days it drove me nuts, had to walk away and do other payers as i contemplated this bizarre turn of events. The supervising super tech at the company did all the same tests i did, called tech support. No dice. I started exploring EVERY possible data parameter. As i stumbled through every possible menu in the scanner looking for ANYTHING that could help, i find an option buried in the engine side (Snap on scanner) "reset engine adaptives". CLICK!. THE PROBLEM WAS GONE. I was thinking it was something like that on Eric O's headache. First time i had ever seen that as a menu option.
I was a computer tech in the navy. Our Crypto computer went down. Replacement part on the other side of the world. We were left on our own until part could arrive in the middle of the Persian Gulf. So....I broke out the Motorola IC Chip schematics of what parts this IC chip took the place of and built the part on a cardboard box. IT WORKED! We were back online with the crutch i made from parts. All kinds of resistors diodes and zener diodes (adjustable) power and so forth. What am I getting at you say????
After market parts like the one you replaced may have been made with the same parts but not the same quality parts. ie: resistors with +-5 or 10% diodes with flakey electronic back flow construction. These cheaper made parts do not perform with the tight tolerances of OEM parts. That's why you can buy them at a lower cost. It seems to me your guess work (experience) is more valuable than you take credit for. Nice job. I think the question or problem lies in the construction of the part.
Some Engine computers are probably so sensitive, that if they pick up small anomalies, or slightly off-time feedback events from aftermarket electronic parts, that it triggers the check engine light, and limps the car. That happened to me with an ‘02 Toyota Camry spark plug coil. The original coil was replaced with a China made aftermarket turd coil, because it wasn’t firing #2 cylinder, and I was a broke joke back in 2009. It worked well for about 2 months, then the check engine light came on. This time it was a PO302 (Igniter malfunction code), and a limpy car that would shut off if you accelerated too hard on the road. I suspected that the China made coil was culprit, and bought some used original Denso coils from the junk yard, and replaced it. Problem solved. No check engine light, and No more limp.
Never buy aftermarket electronic parts for newer vehicles!!!! Buy original.
13:25 OMG YOU DIDNT TORQUE IT!
.
ya, and its not going to be.... unless you pay me to pull the motor
no way to get a torque wrench in their (u joints sure, but 20 foot pounds at the wrench is NOT 20 at the socket)
I looked at the wave form and took measurement of the time it takes the sensor to go down to 0v after hitting its 5v the the old one it took 905ns and on the new one it took 405ns and did you measure the resistance of both ckp sensor sorry i suck at explaining
The overall duty cycle is 7% less for old sensor. I would say that the old one started to drop down earlier and trailing edge time was longer. Depending what voltage ECM interprets as zero, the difference will be more than 7%.
Almost all sensors look the same new or not after you clean off the dirt. BUT EVEN THE NEWEST ONES FAIL AT ODD TIMES & WITHOUT WARNING.
I know three retired Chrysler engineers who were very familiar with the JTEC PCM. While all generally praised it, the word around Auburn Hills was that JTEC was an abbreviation for "jus' tryin' to be an engine controller". I wouldn't be surprised to find a line of code someplace that checked for Brand X parts!
I have a 2001 Wrangler 4.0L with the same symptoms. CEL comes on at about 3500 rpm under load or sometimes during light deceleration at highway speeds. But, no misfire is felt and engine power feels good. The crank position sensor has been replaced with OEM part several times. Problem still there. Two local shops have used their parts cannons on it. Problem still there. Last shop suggested replacing the ECM. I'm still thinking about it but don't want to pull the trigger until it can be verified. I need to find a good shop in the Albuquerque area that can do a real diagnosis (lab scope, pressure transducers, etc) and verify before hanging parts.
Wao!cant believe you got 97,000 subs..i remember subscribing i was 1300..lol...keep up.almos you gonna get that RUclips play bottom..
I'm no rocket surgeon but I believe that based upon the data provided that the magnetic response from the old"aftermarket" sensor has lost its effectiveness. That means the magnet wore out. Good parts mean long term results. Bad "aftermarket" parts only last for a short term fix.
Couple years back, a Duralast crank sensor i put on my personal 96 Cherokee left me chasing the tail of an invisible ghost which killed my entire weekend and it was the only 2 days I had off every 45 days. It showed up on a SnapOn scope and a multimeter as working fine hot or cold so I completely wrote it off in my head. Dug through EVERYTHING else, even the ECM software... eventually I took a chance a went and swapped it out at Autozone, and it fixed it!!! ...... for another month. Then the same shit happened. Replaced a second time under warranty, got another 6 or 7 weeks out of it... took it back to Autozone, got the manager to refund my money, went to the local Jeep dealer and dropped the added price on a factory sensor. Never had another problem for the remaining 3 years.
So why does my 95 4.0l idle at about 250 rpm. Cold idle is at 750 rpm. It will sometimes hang for a second at 750 after being revved up, but not always.
IAC has been cleaned and wasn't even dirty to begin with. No codes, but being a 95, its barely got a check engine light.
For idling so low, it does a good job, not as rumbly as I would expect, and never dies. Recently it has gotten closer to stalling, but it bounces back. The engine seems to be very strong and not lacking any power.
New fuel pump and filter, ignition set.
I'm suspecting a sensor, but I'm not finding anything to lead me in any direction. I'm not trying to replace everything under the hood, although I'm getting close with this being a 22 year old Jeep.
Crank sensor ... bet $ it's aftermarket
Mine misses at idle slightly, new EVERYTHING, give it a little gas and brake and smooth as glass, pass a slowpoke on the hwy and hit 4k rpms (all the cammed 4.6 needs to walk it in a hurry) flashing light but no miss.. just don't want to buy another sensor ☹
Just changed my crank sensor today (Mopar OEM). I strongly recommend taking five minutes to drop the driveshaft at the differential. I swung it over toward the passenger side and ziptied it to the catalytic convertor. I was then able to gain much better access to the sensor bolts. I only had to use one extension and a wobble joint and was actually able to reach around the exhaust and get both hands up into the area to start the bolts when reinstalling. I still had to work by feel but it was much easier than fighting the driveshaft. I hope this helps those of you facing this repair.
The Mopar Crank sensor using a specific code and pulse to communicate with the PCM (think of it like to encrypted phones taking to each other). The aftermarket ones are close but not enough to be registered 100% with the PCM. So there Crank sensor is saying "We're all good dawg" but the PCM is only recieving "We'r al d daw." Some are so off they won't even start even though the scope looks good.
Just wanted to add if you have to but aftermarket sensors the ones that will give you little to no trouble is Standard Motor Products. This goes for ALL MOPARS. A few of us guys on the forums fingered out why they didn't work when we were watching the programming in the PCM itself.