Just saw this video for the first time.... feel compelled to share thus: I learned back in 1972 to use a 10 dollar Cal-Van vacuum gauge for my first engine diagnosis by my mentor, a Rolls Royce Master. That lesson, through the years, has kept me from shedding many frustration tears, except when I've strayed from basics! It even cost me a job when I worked at Cadillac in the 70's because we had a prima donna driveability guy who thought the way to cure a misfire was to rev the hell out of the engine! He had a Sun Interregator at his disposal and he never hooked up the vacuum gauge to any of the cars he was charged with fixing. I love your videos! Keep up the great work! I showed him how to diagnose an internal idle air bypass with a vacuum gauge. He had fought this car's rough idle for days. My intent was to help, but his ego was bruised, and me being an upstart kid got the boot!
@@plowe6751 Idle air bypass is necessary on any carburetor, otherwise, at closed throttle/ idle, the engine would run very rich or flood. Some carbs had idle bypass adjustments. This is a very sensitive setting. On the Quadra-Jet (GM) models, the passage is calibrated and non-adjustable. The Vacuum Gauge was not stable at or near 20 inches of vacuum at idle (Normal for here where we are close to sea level). The gauge was fluctuating smoothly between about 13 inches and 16 or so inches. I could take a dental tool and put the bent end into the idle air passage inside the primary bore, and the engine would run smoother as the vacuum would improve due to me partially blocking off the excess air.
Wish polititions were like you ... When you miss somthing or make a mistake you have the balls and honesty to tell us . That gives us faith and trust in you .. I'm from the uk but think you should run for president .keep up the good work .
thanks man. you are so right. these techniques take a lot of time to talk about but are so fast to use. and at times more accurate than any old school test you can do.
I have watched this video a couple of times and really learned from it. There are some very important technique points raised and need to e learned from. Jumping to conclusions is easy, anybody can do it but the importance of not doing that and getting the facts straight is everything! The importance of data comparison is vital. Asking yourself" how is what I see different from know good reference data?" Is vital. Knowing where to look and what to look at saves so much time money and effort. Anybody who claims they can diagnose a fault like this by eye without getting the data and analysing it properly is either an engine whisperer or a fool! Get the data, analyse it, confirm it and get it right, first time.
you are missing the point. you cannot always use conventional testing methods to ID these kinds of problems. on some engines you cannot get to the rear spark plugs without removing the intake! how are you going to verify no compression or a jumped chain on this design without intake removal! what if you remove the intake and you are wrong in your assumption? what I am trying to do, as I said in the video, is to develop other testing methods, to add "tools to our tool box".
I can't help but look at this and think all the money mechanics charge for repairs are so worth it! Part wrench and part tech and engineer.I am an electronics technician and aloy of the scope material you present is great.Being a carburetor and point-gap guy I have to replay stuff to see how it is applied to an engine.For the most part,I get it.Have built a few motors in my day and am pretty handy with a wre ch.
I do not think the variable cam mechanism would cause the chain to be off to the point that it would cause a no compression problem. but it is a great question and something that would be checked more closely when the timing covers were removed.
I’m going through this issue right now. Codes p009 p0008 p0016 p0017 p0018. Cleared codes and they come back. Issues. Runs rough. Checked compression and bank 2 2-4-6 have 150psi. Bank 1 1-3-5 have 200psi. I’m opening the valve covers to see what’s messed up. Thanks for showing us something new.
Please this isn’t a sales pitch🤣😂 got me cracking up. Appreciate these videos. I’m a self taught mechanic and use your videos to learn the things I need to to solve problems on my personal and friends and family vehicles. Thanks
Just got done doing compression tests on a 2003 3.8 dodge caravan and had exactly that problem no compression on 135 and i was like WHF . So now ive got to figure jumped chain . thanks for the video gives me a point to start with
Thanks Paul,it’s so easy to get misled or confused in this game what with so many different engine configurations etc,I must admit when you cranked over this engine at the start of the video it didn’t sound at all like it had missing compressions to me either and I’ve been a tech for 30 yrs so it just goes to show that you can take nothing for granted....brilliant diagnosis by the way....Many Thanks 👍🏻
Awesome work Paul,for the guys that don't understand or are scared of using a scope,Dan is a teacher,yer you could of done it a different way,but sometimes you gotta do it this way too,also for us and his class as a demo on rel comp he could of found the problem in no time at all how ever making a vid in front of a class takes much more time,i watch your vids every night while iam relaxing as iam a tech in australia love your work brother
that is correct my friend. we didn't though because of the difficulty in accessing the 1 rear cylinder you can get to. The other two are under the manifold. plus, going into this job and by the way it sounded to me, I never suspected 3 dead holes. it truly wasn't even on my radar for a while.....my fault for sure
I love this video I remember watching it about 4years ago it will keep you a out of the rabbit hole. One thing I would like to add is the crankcase waveform over the dipstick tube barring you don't have a piston ring issue on all six pistons the waveform is solid as far as peaks and valleys in this case the relative comp showed 3 peaks in 2 crank revs the crankcase will always show 6 even with a jumped timing chain or a total loss of compression as if you removed all spark plugs great video SD
Great video! I just experienced this on my own 2013 Impala, with 190k. Car ran perfect, when driven last. Went to start it the next morning 15deg outside and it wouldn’t start. No codes, good fuel pressure and spark, I pulled the front plugs and checked compression 95/85/90 on the front bank. I pulled the intake and checked the rear60/20/35. 😢
no, it is very common to only have one cam sensor. and on this one I would say yes, the multiple cam sensors is used for control and diagnosis of the variable valve timing
knowledge is the resultant of learning,your in a new field it will take time to master the quirks of the advanced engine designs,with them changing every 2-5 years
I have learned that the sound of relative is not always accurate especially VCT engines. I seen a tech once that was going to sell a 5.4 ford engine based on relative sound when I walked over and did a clear flood to get the engine to start. That was a good eye on the relative humps, never seen one like that but I will store that in my memory for future. Thanks Paul
Amazed more people don’t seem to watch these videos. Cant fix a problem if you cant figure out the cause of the problem. Unless you fire the parts shotgun and a piece of the shot actually hits the cause so to speak. And ive seen plenty of cases to almost call it a rarity. Cant get enough of these videos. At worst they give a different perspective 👍😁👍
The sound was even because of the firing order, 1-2-3-4-5-6. Every other cylinder was good, thats why you didn't hear a problem. Had the firing order been different, you may have been more apt to notice right away. I am loving this guys brain! Holy s&^t he's smart!
Hi, I agree with Paul. Knowledge is the power. If you are smart, you should learn both ways (old school and Modern techniques), based on your experience, you should either one(old school or Modern) to resolve it.. What Paul is doing is explaining in details to every one of us.. If he don't want to explain may be he can do things very quickly but that is not his intention.. when u explain to newbie it take hell lot of time.. hope u got my point
Hi Paul,Here in Tunisia I have found some electronic dealer who told me that he could deliver me the kits at the international price HT.Till now I should wait for half a month to get the kits.You know here it is not possible to buy online. I verified the price that was almost unique for all websites (I have visited).I hope that I have well done.Just I want to tell you that I have seen very cheap chineese automotive PC based labscope but I was not confident in it. thank you Paul.
Just additional FYI. The wide and tall crank pulse is likely from a "missing" tooth on the crank wheel. It is not broken, but missing by design to show a reference point on the crank. Some system do "double fire" (fire plugs as pairs, one on compression, one on exhaust) until enough revolutions have occurred to be 100% certain that the cam and crank signals are properly synchronized.. Another reason to use crankshaft position sensor for reference while doing test during cranking.
great info my friend. thank you for that! I definitely need to go back and watch that part again. it is possible i miss labeled that cyl head. so if it was a stuck cam phaser, would the repair still be a complete disassembly of the timing covers?
Hi I'm doing timing on a 11 chevy traverse and after taking everything off and was getting ready to set timing b4 taking chains of and noticed that it gets stuck wont turn a full turn any help would be appreciated.......p.s. b4 taking everything off i cranked it a few times with out any issues
@@sadboy8413 why are you doing the chains? You may already have a bent valve? Post this to my forum www.scannerdanner.com/forum/post-your-repair-questions-here.html we can help you more there. It is free to join. Thanks!
Hi Paul, my friend Eric O. at South Main Auto just ran into this exact scenario on a 2005 Ford 4.0 V6...relative compression humps looked great, until I suggested to hook up a sync channel (this video really stuck in my mind!)...sure enough three humps were missing! My question is how can we have no compression or vacuum AT ALL inside the combustion chamber if the timing is off, but the camshaft is turning. I mean those valves should be closed and sealing at some point in time right? Unless all the valves are bent lol
+motoYam82 coul be bent, but it could be timing too. If either valve is open during the compression stroke, then obviously there would be no compression. They may be closed and sealing during the intake or exhaust strokes.
Sure, but in general if the valves are sealing and the piston is moving (up or down, doesn't matter which stroke), there should be a significant change in pressure in the combustion chamber, right? Just wondering if we can use the in-cyl transducer to accurately see if we have bent valves inside...
+motoYam82 At 19:00 the "dead" cylinder waveform can still tell us something. 1) We know that the cams are still turning, as shown by the two cam sensors. 2) The small pressure humps are less than 0.1psi peak-to-peak in amplitude. I would put money that the valves on that cylinder are NOT sealing the chamber at any point in time, i.e. they must be BENT and sticking open. 3) In 720deg of crank we see THREE distinct humps on the dead cyl waveform. Not sure which cyls are "backfeeding" pressure, but that again proves those valves are not sealing... So basically can we say to the customer: your cam timing is definitely off. However, there also appears to be valvetrain damage to the rear cyl head...much more expensive than just resetting the timing!! In that case tearing the valve cover off would almost be a waste of time...might be more economical to just swap the entire engine :)
+motoYam82 Not if the valves are closed during the downward movement of the piston and open during the upward movement. your cranking compression test will show basically nothing but your in cylinder transducer may reveal your issue. Not sure, I think there would be variables there too.
+ScannerDanner Yeah I was thinking of the in-cylinder transducer which shows pressure and VACUUM (so valves sealing on a downward stroke would show up as vacuum). The traditional compression gauge and relative comp test wouldn't provide any additional info here... Will definitely keep an eye out for engines with timing issues to get some waveforms. Ever seen a Chevy 2.2L Ecotec with poorly sealing exhaust valves? Just got one in the shop here with a cyl3 misfire...reminds me of your Hummer misfire case study!
Hello Paul, I will receive my 4 channel standard kit + transducer kit soon,I'm really so interested by these techniques of diagnosing. Even if their prices are too expensive for a beginner I have decided to go ahead.
Thanks for another great video. I had one of these in the shop today and used your bank 2 wave form for my known good. My case was different though mine would run but was dumping raw fuel out of the exhaust. bank 1 intake cam jumped. I am an L1 Master also but still consult your videos and book frequently. Your doing an awesome job keep it up!
picoscope, snap-on Vantage Pro, snap-on Verus, and also look up something called a uScope from aeswave d o t c o m. This uScope is a single channel inexpensive scope that is great for people just starting out.
Had same 'fool you' experience on a 1 camshaft engine. Car seemed to run fine on higher RPM, terrible on idle. Monopoint so no injection issue, had 1 one plug wire which tested OL ohm when twisting so open. Cylinder drop test gave me spark but also 2 missing cylinders (!) from the 4. These were 2 and 3 on a firing order of 1, 2, 4, 3 so that explained reasonable running (lacking power of course) on higher RPM. These 2 cylinders ran on 1 of the 2 coils and you would easily be fooled into thinking the coil was the cause if you did not reason like a diagnostic guy should. Testing a bit further, relative compression test showed equal humps but did not feel right. Brought in the sync channel and only then noticed we had 2 cylinders and 2 with absolutely NO compression so it fooled me on first test (looking at scope image). Difference with your example; on a 4 cylinder, 1 cam car, a loss of compression on 2 cylinders is no timing issue. It is more likely valves, head gasket (not now, we had NO compression) or piston rings but that is another story. For this little 600 dollar car it was game over (too expensive to get this fixed) but there you go... how a first impression can fool you.
This SD is very interesting material, and puts away forward for me to tackle a problem i have at the monent. My concern and little disappointment is that you use a pico to show us this and not a verus, i appreciate its your choice. Not many of us have both , and like me i brought the verus , it would be nice if you can do this with verus one day. But if you have already have can you drop me link please. Thanks for all your work you do . It is alot to take in and fit in with a working day.
I think I show it here ruclips.net/video/WKdZsWU2ZmI/видео.html You do not need to SIA 2000 adapter, it is a P.O.S, just get a single test lead for COP ignition systems to use as your sync on a plug wire or ignition coil. I have the ones I use listed on the tools page of my website. www.scannerdanner.com/dmm-and-lab-scope-accessories.html
@kevin I doubt it.....to tricky to get all those cilinders to tdc.@paul how about to check cam an crank signals, while you activate the variable camshaft actuators? Verus does the activation and pico shows you the signals...one way to check the timings. If the camshaft is really broken, you can test that with this method.
you have to cut me some slack man. this car was towed back to the garage that brought it to us. I have had no updates from them and truthfully I haven't asked for one. The main purpose of this video was to cover "relative compression testing variables" not "how to fix a no compression problem on three cylinders on the 3.6 engine". I realize you would like to know what exact mechanical part failed with the chain and so would I, I just don't have that info.
ScannerDanner agree 100%. Seen many of these engines. Total garbage. Best thing to do is remove intake hose and feel with your hand on throttle body while someone cranks engine. If not uniform suction during each cycle.. tell customer time for a new engine if you can find one. These engines are total garbage and way over engineered. Just looking for trouble. A 3.8 supercharged would put out close enough to the same powered and are tested and true. I am a tech and 41. They call these 3.6 l a high feature V6. I laugh and call it a high maintenance V6. Anyone else agree?
GM dealer tech here. Gm doesnt rely too much if at all on scope diagnostics and yet when this video started and I saw the capture you initially showed, I asked myself immediately "why is there only 3 humps?"
+ScannerDanner I really like the way you teach. Your presentation is perfect and you make things extremely easy to understand. Just wanted to compliment you on that. And as far as you nor catching the missing 3 extra humps on the scope, believe me it happens to the best of us lol. In my career I have overlooked a lot of captain obvious stuff due to haste.
+ChicanoBluesAZ Every tech that claims not to miss things that are obvious so once and a while, is either a liar or a real superman. Think we all have our share of 'why did I miss that' issues (a terrible journey through wires and digging out computers for a fuse issue is one I remember really well)...
Found this video and your others when showing a customer links to info on jumped 3.6L chains. Paul, as a fellow Master Technician for over 25 years and about the same time since I joined iATN when they had 400 members - I can say that is just brilliant! I pride myself in knowing there is a test for everything, and have a nice collection of equipment and know how to use it. I do have a 2 channel Pico, along with an old Vantage, OTC Genisys scope, along a lot of other neat stuff. Have dealer level hardware and software for at least 7 manufacturers, and do programming on most also. I do not (yet) have a pressure transducer but after watching this video will be my next purchase. Also in having computer and electronics interests, I love your touch screen projection "board". What is that and how does it work? I can Google it to figure it out but wanted to compliment you on your experience and attitude. Kevin in Maine
Nice Video Paul.. Awesome explanation. Nothing related to this video, but on 6 cylinder engine, can I safely assume we will have 2 CAM sensor one for each bank minimum.. ?.. second, in this video, they have 2 CAM per bank , one for intake and other for exhaust, do u think that is for Variable valve timing monitors?.. pls advise
I was actually thinking about this COP system and I remembered that the Ford systems actually fire both coils of the companion cylinders until it receives the CID signal from the CMP sensor/s. I wonder how that would look. I'm going to have to do a relative compression test synced with a coil on one of those just to see. This car must have set cam correlation codes?
I just went back and looked, there is no way to know if I had my leads connected wrong on the back cylinder head but I did notice that the "red trace" is also off, (one tooth) on the back cylinder head compared to the front. with that info. I believe we have more than just one stuck or broken cam phaser. what are your thoughts?
@toyotatech I meant while you run the engine....does the vvt work, you can assume that all camshafts are fine. Had the same probleme with a 4 cil. gm engine.
That's true too. However, on my car that would knock out the crank sensor completely if the sprocket wasn't turning. Great point though as I imagine there are plenty of cars that don't operate that way which is why I watch ScannerDanner and others. :) Paul, in both instances you are using a labscope that most don't have access to, DIY'ers would have pull it apart. Great video for techs though nothing wrong with that.
have done a few 3.6l timing jobs on acadia and vue and treverse but doing a Saturn vue it jumped time guy took heads off had them redone but heads back on before i come into the picture i lined up all my marks like I always do no issues now that i got it all timed and goto rotate by hand i get about 1/2 rotation and it stops like its hitting something rotate backwards and stops in same spot number 6 cyl piston up and number 3 what could be the issue ? ive used my inspection camera and valves are open and pistons are up but do not appear to be hitting ive retimed it twice and same issue
hey paul after watching the video one thing came to mind which was the variable valve timing actuator or solenoid for that bank 1 intake cam could possibly be the issue.what do you think?
I take it there are 2 separate timing chains on that vehicle? If no and there is only 1 chain and it's broken then how can you get 3 dead cylinders and 3 good cylinders with a good chain?
The only thing that blew my mind is that touch screen projector, you have great videos , that tools awesome . I have codes P0016 17 18 and 19 ... any idea why? Throwing all those sensors codes does that mean something certain ?
spark, fuel or compression and all three need to be tested, find out what you are missing and then we can go from there, otherwise we are just guessing
So the valves were closing way off that there was no vacuum and a little compression in the intake at the wrong time. Unlikely to see so many jumped teeth but good to know for sure.
Just me, but I think I might have grabbed the crank pulse instead of one of the spark control line to begin with. I certainly would not have bothered looking a the cam signals, because they can vary a lot during cranking (cam phaser work off of oil pressure which is inconsistent during cranking). Perhaps (only perhaps) it may a been obvious during 720 degrees of crank rotation that there were only 3 starter current peaks (compression events).
Hey Paul I have 2007 Lincoln MKZ I have low compression on cylinder 5 only just wondering before I jump to conclusion thinking it's the valve or anything like that could have possibly be crankshaft sensor.?
Hey scannerdanner when you hooked up that backprobe to the primary signal wire of the coil pack does that probe measure current or are you measuring signal voltage? How does starter current draw dictate how many humps are on the scope? If you had no compression on three cylinders you are missing three humps why is that?
Is that a direct fuel injection engine? If it is I found this. Pressure Diagnostics You will never find a Schrader valve or port to measure pressure on a direct fuel injection system, even on the low side. If you were able to tap into the low side with an analog gauge, you would see pressures rapidly changing as demands on the engine changed. Direct injection pressure is measured with sensors, and the signals are used to determine pump speed and/or volume. So, you’ll need a scan tool to look at the pressures.
If these engines are out a tooth would they still run? Replaced timing chains ,guides, and tensioners on my and still have p0017 and p0008 with misfire , suspect im off.
Hi Paul! Once again a very nice video! If you would have been looking at a control signal for a regular coil firing two plugs at the same time the relationship between starter humps and timing would be ok? Is is not quite an easy mistake to do when working with different ignition systems?
How does the computer know when there is bad compressions? It seems to me that almost all test can be shown from computer data lines, because of all the feedback to and from computer. Its all there, just have to know how to read am i correct? I am learning so i have not yet grasped my theory. But all the hookups your doing are already being done in some form or another. In fact it seems to me vacuum pressure hertz would narrow it down.. and so on....
Hi Paul. im thinking about buying an oscilloscope, but is it necessary that i buy an amp clamp to use it for a relative compression test like you do? i can't just pierce a wire and measure current like that with the scope. i know i cant measure it like that with a multimeter unless i put it in series. but is it the same with a scope ? are the leads of an oscilliscope set to read current with one one lead like a clamp does? or do i have to put them in series as well ?
+ScannerDanner okay. sorry for the dumb questions lol. I'm just a DYIer trying to learn more and more. plus, i can follow your videos better if i get one and take my Diagnostic skills to a whole new level. i really don't want to have a "swaptron" mentality just throwing new parts to cars thats why im trying to learn the right way by watching your videos. thanks for all your time btw bro
@9:25 it all clicked! I actually had noticed that there weren't enough humps between the ignition events. I couldn't figure how the cam and crank sensors would tell it to fire like it was a three cylinder? I assumed that there was an ignition timing issue and it was firing before rotating 720 degrees. Not seeing ANY sign of compression between the even peaks totally tricked me! After the epiphany I paused the video to think of ways to make sure I couldn't be had again! 1) If you knew the cranking rpm, and used your scope to measure the frequency/period of the waveform you could compare that to the actual engine rpm to confirm the ignition timing is correct & that compression humps are missing. 2) Another way would be if you used 3 channel's on a scope. Done the same way as you had in the beginning, but one more channel for the next cylinder in the firing order. An ignition signal would show up in the 'valley', revealing the hidden compression stroke! Maybe these would be viable tests, hopefully someone can let me know? Love the channel & content, keep up the good work!
Awesome !Simply fantastic..And by the way loved your book.I bought the e version of it.It would be nice to be if I could use it off line though.Thanks for sharing your knowledge .
What if it was a waste spark system wouldn't that be be what the firing event in comparison to compression look like? This was my first initial thought was. am I wrong
Is this true on a 2.5 nissan w/ dohc? The pre cat clogged and caused a miss on no.3 so installed header and new head gasket along w/ valves × rings. Put it together and still have miss. I think one of the cams are out a tooth or more. Please get back to me with your input.
You have a single cylinder misfire or an entire bank misfire? Also you said the cat was plugged but then you did cylinder head work?? I'm not following why you did that. If you have a single cylinder misfire, we need to find out what you are missing. Spark, fuel or compression
@@ScannerDanner Well, also when checking the bucket clearances I couldn't get a feeler guage between the lobe and top of the valve bucket ( new valves). So I thought this could add to the no.3 cyl miss. I have another head w/ more miles and thought of switching some of the buckets to get clearance?
I don't actually own a scope but recently ordered a new Pico and cant wait to get it and start using it. Love all your videos too!So just a thought .... Initially in this video you took the capture and just had the relative compression wave to work with . Without seeing the ignition event you assumed that the compression was good because of the way everything was uniform with the wave. Working with the initial capture if you had looked closely to the time that it took to get your 6 compression "humps" couldn't you have been able to see that the amount of time it took to get those "humps" was too long ? If the engine was healthy you would see the 6 humps in a smaller amount of time ? am I understanding this correctly ?Thanks again for the videos ! They are awesome .
No problem ! Iam just glad that I was able to grasp the operation of the scope from watching the video. I have a feeling that after getting the picoscope I will never diagnose another car without it !
don't know if some one already said this but I believe the firing order on that eng is 1,2,3,4,5,6 and that is why you didn't think you had a compression issue at first. If the eng would of have a different firing order you would of heard it. does that make sense?
Hey Paul I don’t know if you get this or not but I have a 3.6 Arcata that did the same thing. Was wondering if you found out that if that bent any valves And did you come across any other captures for that cylinder head? Thanks Doug
sorry man, no and no :-( I was happy just to ID the issue and send it to engines class, then engines class didn't want it (too busy at the time) so the car left
One of the cars that we love is doing the same thing, IT SOUNDS EXACTLY LIKE THIS ONE WHEN TRYING TO START, I know there is some misalignment because there were 2 specific errors for cam and crankset. Is there s chance replacing the timing belt will fix this? WE HEAR NO SOUNDS OF METAL ON METAL WHEN CRANKING OR WHEN THIS FIRST HAPPENED. This is so old I bet I do not get a reply. :-)
Dan, once again - thank you for another great video. I've seen these exhaust pressure transducers (firstlook brand). I am wondering if you've had any experience using rather than relative compression particularly on v6 and v8 for this example? I would have to think it would make more sense to use something to that effect considering how tough it is to reach the back bank of the engine. If you have, I think it would be great if you can share your experience with them.
Hi paul excellent video as always, thanks for sharing it. I have a couple of questions, you said on video at around minute 20 that the CKP was a VRS, and its signal varies due to cranking speeds, so the higher amplitude on the capture (same minute of the video) can be explained by the missing humps?, also I noticed the slope to the right of the humps are longer than the left and not even. What do you think?. Can we use these in the analysis?. Thanks.
ScannerDanner Premium Thank you for taking the time and short reply. Sorry, my mistake, I wasn't clear probably because of my english. I meant there is an increase in the amplitude and I believe the frequency of the signal of the CKP, but I´m not referring to the sync notch, but the several waves that get wider and then shrinks back, and second I´m not sure if slope is the word but the cylinders that are contributing made the humps in the graph but are not symmetric, they are like an inverted V but one leg of the V is longer than the other, Hopefully I'm clearer now, I tried but my english needs practice. Thanks again.
Atacama777 No problem! Wish I knew a second language. I think you're doing great. Anyway. The waveform increases and decreases in amplitude simply from the crankshaft speeding up and slowing down. It is a characteristic of a VR sensor. The reason for the crankshaft speeding up is from the no compression cylinders and what slows it down is the compression in the 3 good cylinders. Hope that makes sense.
I have the same motor in a Cadillac CTS with 175 pounds compression on 5 cylinders and 0 pounds on number 6 cylinder I had a bad intake lifter so I replaced it and put it all back together and still have no compression engine still will not start. I first thought it had jumped time. Am I looking at the wrong thing here?
i have a question. in the video you synchronize your relative compression readings with a single ignition firing event. if you did that with the back cylinders then the sync signal would be seen on the gap between 2 of the 3 homps correct? could that lead us to misdirections as far as what to test next?
I'm confused please help, how does starter current relate to compression? if the timing jumped, would it have also been viable to sync crank sensor and spark together too see if timing is good?
It is becoming more and more difficult to answer questions here. I have 80,000 people asking me for help now. So I have created a forum to help you guys better. It is free to join and we can exchange pictures, wiring diagrams and waveforms if needed to help guide you through the process of troubleshooting your vehicle. Thank you so much! Hope to see you there. Paul Danner (ScannerDanner) www.scannerdanner.com/forum/post-your-repair-questions-here.html
Greedings Paul, for the correct timing you say the spark must happen exactly at the top of compression peak.whenever it is not you say timing is wrong. someone agued me saying spark must be few degrees before tdc. atleast 10 degree. so that fuel mixture have time to ignite and at tdc that is when it will be fully effective. i never heard you mentioning that anywhere. BLOM MOSHITOA (S AFRICA)
Not sure I used the words "exactly at TDC". It is absolutely common to see timing anywhere from 10 degrees before to even after TDC. Had a Lexus that was at 7 degrees after TDC and it was normal during a cranking situation
Just saw this video for the first time.... feel compelled to share thus: I learned back in 1972 to use a 10 dollar Cal-Van vacuum gauge for my first engine diagnosis by my mentor, a Rolls Royce Master. That lesson, through the years, has kept me from shedding many frustration tears, except when I've strayed from basics! It even cost me a job when I worked at Cadillac in the 70's because we had a prima donna driveability guy who thought the way to cure a misfire was to rev the hell out of the engine! He had a Sun Interregator at his disposal and he never hooked up the vacuum gauge to any of the cars he was charged with fixing.
I love your videos! Keep up the great work! I showed him how to diagnose an internal idle air bypass with a vacuum gauge. He had fought this car's rough idle for days. My intent was to help, but his ego was bruised, and me being an upstart kid got the boot!
In the words of marky mark, ego is not your amigo. Think i just lost a job over it. Really wanted to move to texas too☹️
@@plowe6751 Idle air bypass is necessary on any carburetor, otherwise, at closed throttle/ idle, the engine would run very rich or flood. Some carbs had idle bypass adjustments. This is a very sensitive setting. On the Quadra-Jet (GM) models, the passage is calibrated and non-adjustable. The Vacuum Gauge was not stable at or near 20 inches of vacuum at idle (Normal for here where we are close to sea level). The gauge was fluctuating smoothly between about 13 inches and 16 or so inches. I could take a dental tool and put the bent end into the idle air passage inside the primary bore, and the engine would run smoother as the vacuum would improve due to me partially blocking off the excess air.
Wish polititions were like you ... When you miss somthing or make a mistake you have the balls and honesty to tell us . That gives us faith and trust in you .. I'm from the uk but think you should run for president .keep up the good work .
thanks man. you are so right. these techniques take a lot of time to talk about but are so fast to use. and at times more accurate than any old school test you can do.
I have watched this video a couple of times and really learned from it. There are some very important technique points raised and need to e learned from. Jumping to conclusions is easy, anybody can do it but the importance of not doing that and getting the facts straight is everything! The importance of data comparison is vital. Asking yourself" how is what I see different from know good reference data?" Is vital. Knowing where to look and what to look at saves so much time money and effort. Anybody who claims they can diagnose a fault like this by eye without getting the data and analysing it properly is either an engine whisperer or a fool! Get the data, analyse it, confirm it and get it right, first time.
you are missing the point. you cannot always use conventional testing methods to ID these kinds of problems. on some engines you cannot get to the rear spark plugs without removing the intake! how are you going to verify no compression or a jumped chain on this design without intake removal! what if you remove the intake and you are wrong in your assumption? what I am trying to do, as I said in the video, is to develop other testing methods, to add "tools to our tool box".
I can't help but look at this and think all the money mechanics charge for repairs are so worth it! Part wrench and part tech and engineer.I am an electronics technician and aloy of the scope material you present is great.Being a carburetor and point-gap guy I have to replay stuff to see how it is applied to an engine.For the most part,I get it.Have built a few motors in my day and am pretty handy with a wre ch.
I do not think the variable cam mechanism would cause the chain to be off to the point that it would cause a no compression problem. but it is a great question and something that would be checked more closely when the timing covers were removed.
I’m going through this issue right now. Codes p009 p0008 p0016 p0017 p0018. Cleared codes and they come back. Issues. Runs rough. Checked compression and bank 2 2-4-6 have 150psi. Bank 1 1-3-5 have 200psi. I’m opening the valve covers to see what’s messed up. Thanks for showing us something new.
This is just the order that I teach my class. I will come back to it next. Thanks!
Please this isn’t a sales pitch🤣😂 got me cracking up. Appreciate these videos. I’m a self taught mechanic and use your videos to learn the things I need to to solve problems on my personal and friends and family vehicles. Thanks
Just got done doing compression tests on a 2003 3.8 dodge caravan and had exactly that problem no compression on 135 and i was like WHF . So now ive got to figure jumped chain . thanks for the video gives me a point to start with
Thanks Paul,it’s so easy to get misled or confused in this game what with so many different engine configurations etc,I must admit when you cranked over this engine at the start of the video it didn’t sound at all like it had missing compressions to me either and I’ve been a tech for 30 yrs so it just goes to show that you can take nothing for granted....brilliant diagnosis by the way....Many Thanks 👍🏻
Awesome work Paul,for the guys that don't understand or are scared of using a scope,Dan is a teacher,yer you could of done it a different way,but sometimes you gotta do it this way too,also for us and his class as a demo on rel comp he could of found the problem in no time at all how ever making a vid in front of a class takes much more time,i watch your vids every night while iam relaxing as iam a tech in australia love your work brother
Thank you Shameel
that is correct my friend. we didn't though because of the difficulty in accessing the 1 rear cylinder you can get to. The other two are under the manifold.
plus, going into this job and by the way it sounded to me, I never suspected 3 dead holes. it truly wasn't even on my radar for a while.....my fault for sure
I love this video I remember watching it about 4years ago it will keep you a out of the rabbit hole. One thing I would like to add is the crankcase waveform over the dipstick tube barring you don't have a piston ring issue on all six pistons the waveform is solid as far as peaks and valleys in this case the relative comp showed 3 peaks in 2 crank revs the crankcase will always show 6 even with a jumped timing chain or a total loss of compression as if you removed all spark plugs great video SD
Great video! I just experienced this on my own 2013 Impala, with 190k.
Car ran perfect, when driven last. Went to start it the next morning 15deg outside and it wouldn’t start.
No codes, good fuel pressure and spark, I pulled the front plugs and checked compression 95/85/90 on the front bank. I pulled the intake and checked the rear60/20/35. 😢
no, it is very common to only have one cam sensor. and on this one I would say yes, the multiple cam sensors is used for control and diagnosis of the variable valve timing
knowledge is the resultant of learning,your in a new field it will take time to master the quirks of the advanced engine designs,with them changing every 2-5 years
I have learned that the sound of relative is not always accurate especially VCT engines. I seen a tech once that was going to sell a 5.4 ford engine based on relative sound when I walked over and did a clear flood to get the engine to start. That was a good eye on the relative humps, never seen one like that but I will store that in my memory for future. Thanks Paul
Amazed more people don’t seem to watch these videos. Cant fix a problem if you cant figure out the cause of the problem. Unless you fire the parts shotgun and a piece of the shot actually hits the cause so to speak. And ive seen plenty of cases to almost call it a rarity. Cant get enough of these videos. At worst they give a different perspective 👍😁👍
Thank you!
Thank you for the good info. One dead hole or a head gasket between cylinders is easy to hear. Can you post an update once it is torn down?
Hey Brother Paul good to hear from ya! Another great instructional.. Thanks for your time... Lord Bless you and yours as always...
Thank you for the video! Good job! Yes, ''V'' motors are sometimes confusing when diagnosing.
hey paul good point about cranking vacuum always look forward to your videos
The sound was even because of the firing order, 1-2-3-4-5-6. Every other cylinder was good, thats why you didn't hear a problem. Had the firing order been different, you may have been more apt to notice right away. I am loving this guys brain! Holy s&^t he's smart!
Hi, I agree with Paul. Knowledge is the power. If you are smart, you should learn both ways (old school and Modern techniques), based on your experience, you should either one(old school or Modern) to resolve it.. What Paul is doing is explaining in details to every one of us.. If he don't want to explain may be he can do things very quickly but that is not his intention.. when u explain to newbie it take hell lot of time.. hope u got my point
Hi Paul,Here in Tunisia I have found some electronic dealer who told me that he could deliver me the kits at the international price HT.Till now I should wait for half a month to get the kits.You know here it is not possible to buy online. I verified the price that was almost unique for all websites (I have visited).I hope that I have well done.Just I want to tell you that I have seen very cheap chineese automotive PC based labscope but I was not confident in it.
thank you Paul.
Just additional FYI. The wide and tall crank pulse is likely from a "missing" tooth on the crank wheel. It is not broken, but missing by design to show a reference point on the crank.
Some system do "double fire" (fire plugs as pairs, one on compression, one on exhaust) until enough revolutions have occurred to be 100% certain that the cam and crank signals are properly synchronized.. Another reason to use crankshaft position sensor for reference while doing test during cranking.
Thanks for the insight...... enjoyed the smart board. (sometimes I don't see the forest for the trees)
great info my friend. thank you for that! I definitely need to go back and watch that part again. it is possible i miss labeled that cyl head. so if it was a stuck cam phaser, would the repair still be a complete disassembly of the timing covers?
Hi I'm doing timing on a 11 chevy traverse and after taking everything off and was getting ready to set timing b4 taking chains of and noticed that it gets stuck wont turn a full turn any help would be appreciated.......p.s. b4 taking everything off i cranked it a few times with out any issues
@@sadboy8413 why are you doing the chains? You may already have a bent valve? Post this to my forum www.scannerdanner.com/forum/post-your-repair-questions-here.html we can help you more there. It is free to join. Thanks!
Hi Paul, my friend Eric O. at South Main Auto just ran into this exact scenario on a 2005 Ford 4.0 V6...relative compression humps looked great, until I suggested to hook up a sync channel (this video really stuck in my mind!)...sure enough three humps were missing!
My question is how can we have no compression or vacuum AT ALL inside the combustion chamber if the timing is off, but the camshaft is turning. I mean those valves should be closed and sealing at some point in time right? Unless all the valves are bent lol
+motoYam82 coul be bent, but it could be timing too. If either valve is open during the compression stroke, then obviously there would be no compression. They may be closed and sealing during the intake or exhaust strokes.
Sure, but in general if the valves are sealing and the piston is moving (up or down, doesn't matter which stroke), there should be a significant change in pressure in the combustion chamber, right? Just wondering if we can use the in-cyl transducer to accurately see if we have bent valves inside...
+motoYam82 At 19:00 the "dead" cylinder waveform can still tell us something.
1) We know that the cams are still turning, as shown by the two cam sensors.
2) The small pressure humps are less than 0.1psi peak-to-peak in amplitude. I would put money that the valves on that cylinder are NOT sealing the chamber at any point in time, i.e. they must be BENT and sticking open.
3) In 720deg of crank we see THREE distinct humps on the dead cyl waveform. Not sure which cyls are "backfeeding" pressure, but that again proves those valves are not sealing...
So basically can we say to the customer: your cam timing is definitely off. However, there also appears to be valvetrain damage to the rear cyl head...much more expensive than just resetting the timing!!
In that case tearing the valve cover off would almost be a waste of time...might be more economical to just swap the entire engine :)
+motoYam82 Not if the valves are closed during the downward movement of the piston and open during the upward movement. your cranking compression test will show basically nothing but your in cylinder transducer may reveal your issue. Not sure, I think there would be variables there too.
+ScannerDanner Yeah I was thinking of the in-cylinder transducer which shows pressure and VACUUM (so valves sealing on a downward stroke would show up as vacuum). The traditional compression gauge and relative comp test wouldn't provide any additional info here...
Will definitely keep an eye out for engines with timing issues to get some waveforms. Ever seen a Chevy 2.2L Ecotec with poorly sealing exhaust valves? Just got one in the shop here with a cyl3 misfire...reminds me of your Hummer misfire case study!
Excellent! I could see how not adding the sync during the relative compression test could throw you off.
yes, a waste spark system would have shown this type of pattern. (where you have a coil firing event every 360 of the crank)
Hello Paul, I will receive my 4 channel standard kit + transducer kit soon,I'm really so interested by these techniques of diagnosing. Even if their prices are too expensive for a beginner I have decided to go ahead.
Good information. Why would the computer not throw a timing code?
Thanks for another great video. I had one of these in the shop today and used your bank 2 wave form for my known good. My case was different though mine would run but was dumping raw fuel out of the exhaust. bank 1 intake cam jumped. I am an L1 Master also but still consult your videos and book frequently. Your doing an awesome job keep it up!
picoscope, snap-on Vantage Pro, snap-on Verus, and also look up something called a uScope from aeswave d o t c o m. This uScope is a single channel inexpensive scope that is great for people just starting out.
Had same 'fool you' experience on a 1 camshaft engine. Car seemed to run fine on higher RPM, terrible on idle. Monopoint so no injection issue, had 1 one plug wire which tested OL ohm when twisting so open. Cylinder drop test gave me spark but also 2 missing cylinders (!) from the 4. These were 2 and 3 on a firing order of 1, 2, 4, 3 so that explained reasonable running (lacking power of course) on higher RPM. These 2 cylinders ran on 1 of the 2 coils and you would easily be fooled into thinking the coil was the cause if you did not reason like a diagnostic guy should. Testing a bit further, relative compression test showed equal humps but did not feel right. Brought in the sync channel and only then noticed we had 2 cylinders and 2 with absolutely NO compression so it fooled me on first test (looking at scope image). Difference with your example; on a 4 cylinder, 1 cam car, a loss of compression on 2 cylinders is no timing issue. It is more likely valves, head gasket (not now, we had NO compression) or piston rings but that is another story. For this little 600 dollar car it was game over (too expensive to get this fixed) but there you go... how a first impression can fool you.
+Henk Moesker for sure! nice job Henk!
That is correct my friend. a waste spark system would have looked very much like this and would have been good.
This SD is very interesting material, and puts away forward for me to tackle a problem i have at the monent.
My concern and little disappointment is that you use a pico to show us this and not a verus, i appreciate its your choice.
Not many of us have both , and like me i brought the verus , it would be nice if you can do this with verus one day. But if you have already have can you drop me link please.
Thanks for all your work you do .
It is alot to take in and fit in with a working day.
I think I show it here ruclips.net/video/WKdZsWU2ZmI/видео.html
You do not need to SIA 2000 adapter, it is a P.O.S, just get a single test lead for COP ignition systems to use as your sync on a plug wire or ignition coil. I have the ones I use listed on the tools page of my website. www.scannerdanner.com/dmm-and-lab-scope-accessories.html
@kevin I doubt it.....to tricky to get all those cilinders to tdc.@paul how about to check cam an crank signals, while you activate the variable camshaft actuators? Verus does the activation and pico shows you the signals...one way to check the timings. If the camshaft is really broken, you can test that with this method.
Another great video Paul, thanks for sharing it with us, I bought your ebook a few weeks ago it's the least I could do. All the best from the UK
cool man, where did you get it from?
you have to cut me some slack man. this car was towed back to the garage that brought it to us. I have had no updates from them and truthfully I haven't asked for one. The main purpose of this video was to cover "relative compression testing variables" not "how to fix a no compression problem on three cylinders on the 3.6 engine". I realize you would like to know what exact mechanical part failed with the chain and so would I, I just don't have that info.
ScannerDanner agree 100%. Seen many of these engines. Total garbage. Best thing to do is remove intake hose and feel with your hand on throttle body while someone cranks engine. If not uniform suction during each cycle.. tell customer time for a new engine if you can find one. These engines are total garbage and way over engineered. Just looking for trouble. A 3.8 supercharged would put out close enough to the same powered and are tested and true. I am a tech and 41. They call these 3.6 l a high feature V6. I laugh and call it a high maintenance V6. Anyone else agree?
GM dealer tech here. Gm doesnt rely too much if at all on scope diagnostics and yet when this video started and I saw the capture you initially showed, I asked myself immediately "why is there only 3 humps?"
+ChicanoBluesAZ nice catch bro
+ScannerDanner I really like the way you teach. Your presentation is perfect and you make things extremely easy to understand. Just wanted to compliment you on that. And as far as you nor catching the missing 3 extra humps on the scope, believe me it happens to the best of us lol. In my career I have overlooked a lot of captain obvious stuff due to haste.
+ChicanoBluesAZ Every tech that claims not to miss things that are obvious so once and a while, is either a liar or a real superman. Think we all have our share of 'why did I miss that' issues (a terrible journey through wires and digging out computers for a fuse issue is one I remember really well)...
Found this video and your others when showing a customer links to info on jumped 3.6L chains.
Paul, as a fellow Master Technician for over 25 years and about the same time since I joined iATN when they had 400 members - I can say that is just brilliant! I pride myself in knowing there is a test for everything, and have a nice collection of equipment and know how to use it. I do have a 2 channel Pico, along with an old Vantage, OTC Genisys scope, along a lot of other neat stuff. Have dealer level hardware and software for at least 7 manufacturers, and do programming on most also. I do not (yet) have a pressure transducer but after watching this video will be my next purchase.
Also in having computer and electronics interests, I love your touch screen projection "board". What is that and how does it work? I can Google it to figure it out but wanted to compliment you on your experience and attitude. Kevin in Maine
I didn't know the "scope" of scannerdanner's reach when writing comment. Very popular for good reason.
Thanks Kevin! It's called a smartboard
Nice Video Paul.. Awesome explanation. Nothing related to this video, but on 6 cylinder engine, can I safely assume we will have 2 CAM sensor one for each bank minimum.. ?.. second, in this video, they have 2 CAM per bank , one for intake and other for exhaust, do u think that is for Variable valve timing monitors?.. pls advise
I was actually thinking about this COP system and I remembered that the Ford systems actually fire both coils of the companion cylinders until it receives the CID signal from the CMP sensor/s. I wonder how that would look. I'm going to have to do a relative compression test synced with a coil on one of those just to see. This car must have set cam correlation codes?
I just went back and looked, there is no way to know if I had my leads connected wrong on the back cylinder head but I did notice that the "red trace" is also off, (one tooth) on the back cylinder head compared to the front.
with that info. I believe we have more than just one stuck or broken cam phaser. what are your thoughts?
How many teeth can this engine jump before interference occurs?
marcussho not all motors are interference they just won’t run or start
Not positive but would say 4 would be the limit.
This is an interference engine like virtually every engine made in the last 20 years.
@toyotatech I meant while you run the engine....does the vvt work, you can assume that all camshafts are fine. Had the same probleme with a 4 cil. gm engine.
When I first saw the relative comp. test I just thought it was a waste spark that we were seeing. It would have got me!
I thought exactly the same thing.
Very detailed video Paul but you make it easy to understand, please could you let us know the outcome?
That's true too. However, on my car that would knock out the crank sensor completely if the sprocket wasn't turning. Great point though as I imagine there are plenty of cars that don't operate that way which is why I watch ScannerDanner and others. :) Paul, in both instances you are using a labscope that most don't have access to, DIY'ers would have pull it apart. Great video for techs though nothing wrong with that.
have done a few 3.6l timing jobs on acadia and vue and treverse but doing a Saturn vue it jumped time guy took heads off had them redone but heads back on before i come into the picture i lined up all my marks like I always do no issues now that i got it all timed and goto rotate by hand i get about 1/2 rotation and it stops like its hitting something rotate backwards and stops in same spot number 6 cyl piston up and number 3 what could be the issue ? ive used my inspection camera and valves are open and pistons are up but do not appear to be hitting ive retimed it twice and same issue
I also noticed the same thing that technical lee said about the captures being mislabeled
hey paul after watching the video one thing came to mind which was the variable valve timing actuator or solenoid for that bank 1 intake cam could possibly be the issue.what do you think?
I take it there are 2 separate timing chains on that vehicle? If no and there is only 1 chain and it's broken then how can you get 3 dead cylinders and 3 good cylinders with a good chain?
Great video. Will you post the confirmation once they tear it apart?
great vid, but quick dilemma, does the base circuit from the ecm shut off during a clear flud mode?
For ignition systems, no
thank you senzei danner for the clarity
this is our problem thankyou. my son and his buddy were pulling there hair out
good stuff as usual, hey paul why did you skip all the fuel sections on your lectures? are you gonna go back to it eventually?
The only thing that blew my mind is that touch screen projector, you have great videos , that tools awesome . I have codes P0016 17 18 and 19 ... any idea why? Throwing all those sensors codes does that mean something certain ?
Your better at using the smart board then my teachers in high school lol
I have a 2009 Chevy cobalt doing the same thing it’s running on 3 cylinders instead of 4 help ? What’s wrong with it ?
@ScannerDanner
spark, fuel or compression and all three need to be tested, find out what you are missing and then we can go from there, otherwise we are just guessing
3rd cylinder is low on compression .
So the valves were closing way off that there was no vacuum and a little compression in the intake at the wrong time. Unlikely to see so many jumped teeth but good to know for sure.
Hey Paul, I don't know about anyone else but, I am curious how you got started with all of your knowledge from the beginning.
Just me, but I think I might have grabbed the crank pulse instead of one of the spark control line to begin with. I certainly would not have bothered looking a the cam signals, because they can vary a lot during cranking (cam phaser work off of oil pressure which is inconsistent during cranking). Perhaps (only perhaps) it may a been obvious during 720 degrees of crank rotation that there were only 3 starter current peaks (compression events).
Stage3performance, I would buy the Hard copy of the book so you are able to highlight and do easy bookmarking!
Hey Paul I have 2007 Lincoln MKZ I have low compression on cylinder 5 only just wondering before I jump to conclusion thinking it's the valve or anything like that could have possibly be crankshaft sensor.?
No sir, unfortunately
Hey scannerdanner when you hooked up that backprobe to the primary signal wire of the coil pack does that probe measure current or are you measuring signal voltage? How does starter current draw dictate how many humps are on the scope? If you had no compression on three cylinders you are missing three humps why is that?
Is that a direct fuel injection engine?
If it is I found this.
Pressure Diagnostics
You will never find a Schrader valve or port to measure pressure on a direct fuel injection system, even on the low side. If you were able to tap into the low side with an analog gauge, you would see pressures rapidly changing as demands on the engine changed.
Direct injection pressure is measured with sensors, and the signals are used to determine pump speed and/or volume. So, you’ll need a scan tool to look at the pressures.
If these engines are out a tooth would they still run? Replaced timing chains ,guides, and tensioners on my and still have p0017 and p0008 with misfire , suspect im off.
not sure, I think so
Hi Paul! Once again a very nice video! If you would have been looking at a control signal for a regular coil firing two plugs at the same time the relationship between starter humps and timing would be ok? Is is not quite an easy mistake to do when working with different ignition systems?
Could a stretched timing chain on bank 1 cause the entire bank to raed 250 psi on compression test and bank 2 read 180 psi?
Possibly
@@ScannerDanner I guess I have to take the timing cover off and see what's up
How does the computer know when there is bad compressions? It seems to me that almost all test can be shown from computer data lines, because of all the feedback to and from computer. Its all there, just have to know how to read am i correct? I am learning so i have not yet grasped my theory. But all the hookups your doing are already being done in some form or another. In fact it seems to me vacuum pressure hertz would narrow it down.. and so on....
this motor has 4 cam sensors, 2 intake/2 exhaust. doesn't it also have to coil packs? a bank 1 and bank 2 each signaled to by respective cam sensors?
Hi Paul. im thinking about buying an oscilloscope, but is it necessary that i buy an amp clamp to use it for a relative compression test like you do? i can't just pierce a wire and measure current like that with the scope. i know i cant measure it like that with a multimeter unless i put it in series. but is it the same with a scope ? are the leads of an oscilliscope set to read current with one one lead like a clamp does? or do i have to put them in series as well ?
+Alejandro Amaro same as a multimeter bro.
+ScannerDanner okay. sorry for the dumb questions lol. I'm just a DYIer trying to learn more and more. plus, i can follow your videos better if i get one and take my Diagnostic skills to a whole new level. i really don't want to have a "swaptron" mentality just throwing new parts to cars thats why im trying to learn the right way by watching your videos. thanks for all your time btw bro
+Alejandro Amaro no apologies necessary my friend. It was a valid question. Just think of the scope as a really fast voltmeter
Okay. For Now... I was thinking about getting one with a 20Mhz Bandwith and 48 Ms/s sample rate.. Is that okay ? Or do i need a faster sample rate ?
@9:25 it all clicked! I actually had noticed that there weren't enough humps between the ignition events. I couldn't figure how the cam and crank sensors would tell it to fire like it was a three cylinder? I assumed that there was an ignition timing issue and it was firing before rotating 720 degrees. Not seeing ANY sign of compression between the even peaks totally tricked me!
After the epiphany I paused the video to think of ways to make sure I couldn't be had again!
1) If you knew the cranking rpm, and used your scope to measure the frequency/period of the waveform you could compare that to the actual engine rpm to confirm the ignition timing is correct & that compression humps are missing.
2) Another way would be if you used 3 channel's on a scope. Done the same way as you had in the beginning, but one more channel for the next cylinder in the firing order. An ignition signal would show up in the 'valley', revealing the hidden compression stroke!
Maybe these would be viable tests, hopefully someone can let me know? Love the channel & content, keep up the good work!
+theomnipresent1 thanks so much!
Am I on the right track with those methods?
Awesome !Simply fantastic..And by the way loved your book.I bought the e version of it.It would be nice to be if I could use it off line though.Thanks for sharing your knowledge .
What if it was a waste spark system wouldn't that be be what the firing event in comparison to compression look like? This was my first initial thought was. am I wrong
Seriously I can't say thank you enough. I'll be purchasing your Ebook soon
You used starter current too see compression because it’s going to slow down when met with resistance (cylinder pressure) and cause current to build?
yes sir
Cool
Is this true on a 2.5 nissan w/ dohc? The pre cat clogged and caused a miss on no.3 so installed header and new head gasket along w/ valves × rings. Put it together and still have miss. I think one of the cams are out a tooth or more. Please get back to me with your input.
You have a single cylinder misfire or an entire bank misfire? Also you said the cat was plugged but then you did cylinder head work?? I'm not following why you did that. If you have a single cylinder misfire, we need to find out what you are missing. Spark, fuel or compression
@@ScannerDanner Well, also when checking the bucket clearances I couldn't get a feeler guage between the lobe and top of the valve bucket ( new valves). So I thought this could add to the no.3 cyl miss. I have another head w/ more miles and thought of switching some of the buckets to get clearance?
@@ScannerDanner The cylinder head work came after a leak down test. No.3 cyl rings were stuck to the piston from the clogged cat.
I don't actually own a scope but recently ordered a new Pico and cant wait to get it and start using it. Love all your videos too!So just a thought .... Initially in this video you took the capture and just had the relative compression wave to work with . Without seeing the ignition event you assumed that the compression was good because of the way everything was uniform with the wave. Working with the initial capture if you had looked closely to the time that it took to get your 6 compression "humps" couldn't you have been able to see that the amount of time it took to get those "humps" was too long ? If the engine was healthy you would see the 6 humps in a smaller amount of time ? am I understanding this correctly ?Thanks again for the videos ! They are awesome .
+Aka Furtado yes, that is correct. I just didn't pay attention to the time base. I totally should have. Great question and insight my friend.
No problem ! Iam just glad that I was able to grasp the operation of the scope from watching the video. I have a feeling that after getting the picoscope I will never diagnose another car without it !
don't know if some one already said this but I believe the firing order on that eng is 1,2,3,4,5,6 and that is why you didn't think you had a compression issue at first. If the eng would of have a different firing order you would of heard it. does that make sense?
Regardless of firing order, one cam being off would have produced the same every other cylinder pattern on any V type engine.
Hey Paul I don’t know if you get this or not but I have a 3.6 Arcata that did the same thing. Was wondering if you found out that if that bent any valves And did you come across any other captures for that cylinder head? Thanks Doug
sorry man, no and no :-(
I was happy just to ID the issue and send it to engines class, then engines class didn't want it (too busy at the time) so the car left
One of the cars that we love is doing the same thing, IT SOUNDS EXACTLY LIKE THIS ONE WHEN TRYING TO START, I know there is some misalignment because there were 2 specific errors for cam and crankset. Is there s chance replacing the timing belt will fix this? WE HEAR NO SOUNDS OF METAL ON METAL WHEN CRANKING OR WHEN THIS FIRST HAPPENED. This is so old I bet I do not get a reply. :-)
Dan, once again - thank you for another great video. I've seen these exhaust pressure transducers (firstlook brand). I am wondering if you've had any experience using rather than relative compression particularly on v6 and v8 for this example? I would have to think it would make more sense to use something to that effect considering how tough it is to reach the back bank of the engine. If you have, I think it would be great if you can share your experience with them.
Great video Danner.Thanks
Hi paul excellent video as always, thanks for sharing it. I have a couple of questions, you said on video at around minute 20 that the CKP was a VRS, and its signal varies due to cranking speeds, so the higher amplitude on the capture (same minute of the video) can be explained by the missing humps?, also I noticed the slope to the right of the humps are longer than the left and not even. What do you think?. Can we use these in the analysis?. Thanks.
No the missing signal is called a sync notch and is used for cylinder ID
Not sure what slope you are referring to.
ScannerDanner Premium Thank you for taking the time and short reply. Sorry, my mistake, I wasn't clear probably because of my english. I meant there is an increase in the amplitude and I believe the frequency of the signal of the CKP, but I´m not referring to the sync notch, but the several waves that get wider and then shrinks back, and second I´m not sure if slope is the word but the cylinders that are contributing made the humps in the graph but are not symmetric, they are like an inverted V but one leg of the V is longer than the other, Hopefully I'm clearer now, I tried but my english needs practice. Thanks again.
Atacama777
No problem! Wish I knew a second language. I think you're doing great. Anyway. The waveform increases and decreases in amplitude simply from the crankshaft speeding up and slowing down. It is a characteristic of a VR sensor. The reason for the crankshaft speeding up is from the no compression cylinders and what slows it down is the compression in the 3 good cylinders. Hope that makes sense.
ScannerDanner Yes, it makes sense, thanks again for your answers and your videos of course, cheers.
where is the crank shaft sensor located
Is it possible to synchronize the ignition and starter current with a one channel scope?
I enjoy learning from you.
Any word from the shop? What did the autopsy show?
I have the same motor in a Cadillac CTS with 175 pounds compression on 5 cylinders and 0 pounds on number 6 cylinder I had a bad intake lifter so I replaced it and put it all back together and still have no compression engine still will not start. I first thought it had jumped time. Am I looking at the wrong thing here?
Wabbit... What did the issue turn out to be? Had the valve been bent when the lifter failed or was it a head gasket issue?
i have a question. in the video you synchronize your relative compression readings with a single ignition firing event. if you did that with the back cylinders then the sync signal would be seen on the gap between 2 of the 3 homps correct? could that lead us to misdirections as far as what to test next?
I am not 100% sure what we did in this video without watching it again but my gut says yes. That is always a possibility in a case like this.
I'm confused please help, how does starter current relate to compression? if the timing jumped, would it have also been viable to sync crank sensor and spark together too see if timing is good?
It is becoming more and more difficult to answer questions here. I have 80,000 people asking me for help now. So I have created a forum to help you guys better. It is free to join and we can exchange pictures, wiring diagrams and waveforms if needed to help guide you through the process of troubleshooting your vehicle. Thank you so much! Hope to see you there.
Paul Danner (ScannerDanner)
www.scannerdanner.com/forum/post-your-repair-questions-here.html
great vid, pauls the man again.
Greedings Paul, for the correct timing you say the spark must happen exactly at the top of compression peak.whenever it is not you say timing is wrong.
someone agued me saying spark must be few degrees before tdc. atleast 10 degree. so that fuel mixture have time to ignite and at tdc that is when it will be fully effective.
i never heard you mentioning that anywhere.
BLOM MOSHITOA (S AFRICA)
Not sure I used the words "exactly at TDC". It is absolutely common to see timing anywhere from 10 degrees before to even after TDC. Had a Lexus that was at 7 degrees after TDC and it was normal during a cranking situation