Unhappy Honda MISFIRE P0300 (Part 1 - Diagnosis - Accord V6)
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- Опубликовано: 16 фев 2024
- This 2006 Honda Accord V6 is running ROUGH at 205k miles.
Owner says it's misfiring at idle, and won't pass the State Emission Test with a persistent P0300.
Plugs and coils obviously didn't help.
Although I suspect what the issue is, let's PROVE it with scientific DATA before quoting the customer on the final repair procedure.
PHAD PRESSURE TRANSDUCER:
www.pinehollowdiagnostics.com/...
IVAN'S PICO WAVEFORMS:
drive.google.com/drive/folder...
2023 Upgrade LAUNCH X431 PRO3S+:
www.amazon.com/dp/B092894STV?...
TESLONG NTS500 Dual Lens Endoscope:
www.amazon.com/dp/B07SQ4FLYX?...
VAMPLIERS:
www.amazon.com/dp/B00LMOAYR2?...
Enjoy!
Ivan 
Авто/Мото
Yo Ivan, next time you're doing an RC test on a Honda, just use your scan tool. Go to active tests and select all injectors off. It's a little quicker than pulling a relay or a fuse 👍🏼
@southmainauto isn't this irrelevant considering Ivan fixed this accord with just a valve adjustment and you ripped the heads off the accord you had in your shop? It seems like that accord would have been fixed with just a valve adjustment like in this video...
You really think I'm that dumb? Like I didn't back the rocker are off and verify the with a leak down test? Like I'd rather pull a head instead of just adjusting a valve lol@@richevans7171
Great diag! It definitely looks like it needs a valve adjustment. One thing I look for when diagnosing these is to graph MAP sensor data once it's warmed up and you see dropouts if the valves need adjustments. I think that is why it is running rich; since it's a speed-density engine, the main input for fuel is the MAP sensor. Thanks for sharing, looking forward to part 2!
Map sensor is what I use as well.
Excellent video and diag. It’s a full time job just to read through all your comments!
In cylinder compression waveform needs to be divided on 720 degree scale to check if valve opening and closing times are different in both banks.
Two ways to check if it needs a valve adjustment: 1: Brandon Steckler shows using a pulse sensor on the intake looking for the signature “M” indicating valve overlap. 2: Honda map voltage pid for valve adjustment. 0.7v good. Anything above 0.7v is suspect
If valves are tight it alters valve overlap which can make mixture rich at low speed
R.I.P. for Navalny .
Ivan, you really need an articulating boroscope. The tip articulates 180 degrees so you can look back at the valves. Also you can use it to look at valve seats with the adjustments. Worth their weight in gold!
It's always the exhaust valves that get tight in every one that i have done and typically missfire on cold start and goes away when engine warms up via the lash getting looser with heat expansion.
The lash gets tighter / smaller on warm up, not looser. This is why valves are adjusted when they're cold.
@@privateer0561 Wrong do your homework...I
adjust my solid roller cam rockers 6 thousanths tighter cold to achieve the hot spec.(steel block/alum heads)
It depends on the engine design and materials. So it should always be done however the manufacturer recommends with no calculations needed that way.
@@montefiveforty1 Wrong for honda j series, valve adjustment is done with the cylinder head temps at less than 100 F.
@@privateer0561Honda engines are different. Lash is tighter when cold, and usually causes cold start misfires.
We had several 4 cylinder Honda CNG cars in our LA D.W.P. fleet. I noticed at about 12000 miles a slightly rough idle. When adjusting the valves at that mileage, the idle smoothed out nicely. I also cleaned the throttle plate and bore, then checked the minimum idle and reset it if necessary.
Those adjustments and cleaning really helped a lot.
I realize the CNG cars were 4 cylinder, but apparently Honda's need that valve adjustment. Let's see what Part 2 video shows.
I am anxious to see the repair video Ivan!
The last guy who did the 100 thousand mile timing belt and adjustment adjusted them wrong damn rookies 😁
Thats why you take it to the dealership
@@LivingTheDream77 HAH!!! Took ours to the Stealership. Had to do it twice because when we came to pick up the car it was clacking like it had 1/4" valve lash! 2004 V6 6 speed coupe.... what a BEAST! Keeping it until it literally falls apart. Even the service manager listened to it at pick up and admitted the valves were WAY too lose.
Stealerships have a large turn around of mechanics, so you never know who you get.
I'm guessing the valves haven't been touched in 205k miles :)
@@PineHollowAutoDiagnostics I've had some dealership bad experiences myself. I have found 2 great options within 6 miles of home.
There's a reason they're called STEALERSHIPS!!!! They take mounds of your money and you RARELY get a fixed veh in return. I've worked for a couple.....
Hey Ivan a quick check to see if you have tight valves is map voltage in the Data list. Anything over 1.0v at idle is a good indication that valves are tight
Excellent video and a solid diagnostic strategy, Ivan! Very curious to see Part 2!
Honda suggests adjusting the valves on the J series engines around every 80,000 to 90,000 miles. But I have heard that it's being suggested to lash the valves at half of that interval. Now I'm not sure how this happens on these engines, but I have been noticing this happening a lot. The intake valves get loose, while the exhaust valves get tight.
And in replay to Ivans question to why only one plug is getting wet with gas. My thought is another common issue on these Hondas is leaking or clogged injectors.
Im suffering a similar but worse situation with my honda
I actually had a 2005 Accord V6 VTEC. It was getting the same codes. I started changing the oil regularly and it quit. Beautiful little car after that. Owned it for 5 years and sold it for double the price of what I bought it for.
It's a great smooth engine. Love those cars, especially if you can find one with a manual trans.
I used to do annual oil changes on a different make. Had issues like oil pressure light, hot engine. Switched to more frequent oil changes, and problems ceased.
Thanks for sharing this information !
Thanks Ivan!
Very very helpful tutorial . Wonderfully motivating . You are catapulting us students to really grasp systems operations / electrical theory / diagnostic equipment set up and so much more. Outstanding videography too !! Thanks for the extraordinary detail and utilizing teaching techniques and coaching cues throughout !! 👊🏼🔥
Once you start removing spark plugs you can put the computer aside and do a physical pressure test on each cylinder and also borescope them
Maybe The Car not happy going to New Jersey it’s like Nope your not going there
Cylinder head gasket done 3.5 Honda Acuras many with 200k never seen one get over that.
Can't wait for part 2! I was thinking air leak on #1, but that would not explain the lower compression.
Bank 1 is rich as a result of misfire on cylinder 1. Combustion event is randomly not happening on cylinder 1, dumping raw fuel into the exhaust. ECU will then cut fuel for that bank (as shown on STFT for bank 1). This will cause cylinders 2, 3 to run lean (and 1 when it does fire). It is likely getting worse as the engine gets hot as the valve clearance decreases as the metal surfaces heat up (valve clearance is specified for either a hot or cold engine). Damaging, as you are washing the misfiring cylinder with gasoline and dumping excessive fuel into the catalytic converter, increasing the temperature within to the point that it can melt.
One other point…ECU will not begin cutting fuel until it goes into closed loop. At start up, it may not even be misfiring at all.
Random miss fire shows as lean in the exhaust. The ECU would be adding fuel in that case.
@@FadetoBlack1463 depends on cause. Look at 18:20 in video; ECU is cutting fuel on bank 1. Misfires can be fuel, compression, or ignition based.
An 02 sensor cannot measure fuel, only oxygen. When you have a misfire, no matter why, there will still be more oxygen than when there is combustion. Causing the fuel trims to show lean. (positive numbers)
@@advancedleveldiagnostics interestimg, since the car was running rich…and is now running lean since the valves were adjusted. Based on fuel trims (18:20 on first video, 12:00 on second video).
I would do a top engine clean with an Italian tuneup. You can get the valves rotating when you do the Italian tuneup.
Great series hosting pine hollow, I'll got with a vacuum leak ( guess) keep on
Electronic throttle body on the 2006 V6.
Also, in 2006 Honda changed an electronic throttle body on the 4 cylinder Accord.
5 hours for valve adjustment is alot.
Adjusting valve clearances on that engine is a scheduled maintenance procedure. But not that many people actually bother. 4:37
why the cars i buy have no timing belts an have hydraulic lifters,,,
Correct. Routine maintenance. On a Honda Fit, i was surprised how much the valve clearances had changed on the first schedule valve clearance adjustment. Later intervals, not nearly as much. Car had 210,000 miles on it when it was totaled by being rear ended while being driven on an interstate.
and you think that is a good thing@@animalcorvair
Because the schedule maintenance is to costly. So they are swapping coils. Plugs . Injectors. Literally shooting the parts cannon.
A scheduled maintenance item that costs 6 to $800 is just silly in a normal street vehicle as compared to one with high performance aspirations. A Honda Civic Si? Sure. A Honda family oriented minivan? Dumb.
New car dealers are loath to discuss the cost of maintenance with new vehicle purchasers just because of things like this. Local Honda/Acura dealer charges $175 an hour. That makes this "maintenance " item cost over $800 before taxes, incidentals like gaskets and fluids.
Mane u are great love the videos
Kevinbarry is right. On the Saturn Vue with a Honda 6 cylinder engine. Valve adjustment is schedule maintenance. A friend ignored it as to much work. Ignored the misfire and valve tapping on his. Can you say blown engine 6 months later.
The factory Honda scan tool has option to turn all fuel injectors off. This is likely available on your aftermarket scan tool as well for compression testing without loosing ignition signals.
You beat me to it. Also, I believe you can turn them off selectively also.
He could have just pulled the fuse to the fuel pump. Instead of messing with the injectors.
There is two fuel related fuse if i recall right. Im experiencing a harsher misfire with my 03 accord v6. Mine is not even able to drive past 25mph@@thatsonebadhatharry8610
beautiful country ivan
Hi Ivan - I adjusted the valves in my 2005 Odyssey at 135K because I noticed it running a bit rough but with no codes set. I found ALL the exhaust valved were under minimum clearance and most intake valves were on the high side. I adjusted the exhaust valves to the loose end of the spec and the intakes to the tighter end on their spec. 0.013 exhaust and 0.009 intake IIRC. Smooth as silk after this and I noticed throttle response was better. Not sure on the specs on your Accord.
In my experience I've found that Hondas with tight valves will misfire more with a cold engine. As it warms up, the clearance increases and the engine will run better (just the opposite of a pushrod engine). That's why Honda says to adjust the valves on a cold engine.
The negative trim is due to enrichment of three cylinders based on the misfire of one.
Can’t wait to see part 2! My TL has 230k, valves never adjusted, it has a misfire at idle but no codes. I’m thinking the valves need an adjustment but was going to wait until I do the second timing belt job, did the first one at 140k. I’m doing plugs soon since they have more miles on them than the timing belt.
I just recently did head gaskets on my wife’s 2010 Forester and your video on disassembling the heads was super helpful! That was the first time I’ve adjusted valves and the car runs smoother than ever now.
Definitely do the valve adjustment ASAP since running the engine with tight valves can damage them!! 😳
Nice. With the SO scanner I can see uneven MAP sensor data on the graph - the one good thing about SO scanners. The 5 hour valve adjustment, usually I find the intakes to be fine and not need adjusting, always the exhausts are the tight ones, so it doesn't really take 5 hours. But I guess it could.
Hi Ivan, have the same with my 2003 accord.. while replacing valve cover gasket,found one of the lobes on exhaust cam cylinder 1 very worn..
Have a po302 on my 2006 subaru sti with 146,000 miles . Stock with spt add ons.hoping this video helps. Did the plug and coil swap. Did intake vacuum .eak check with smoke machine. Next is compression and leak down test. Also gonna swap injectors from cylinder 2 to 4
Another next time tell us get a bag of pop corn and enjoy the show I like your video get to see some nice cool stuff I never afford to buy
I had a 2003 Eclipse with the V6, it ran perfect, every once in a while it would sputter for a couple seconds, pop a PO300 and go back to perfect, never cared to figure it out, but it perplexed me
Measure twice, cut once... Pays off in what you said. "Research and make a game plan... Paying off dividends"
Great work. The only thing I would do different, is comparing cylinder 1 to cylinder 5, because 5 has no misfire. A known good.
Ivan, don't discount that EGR valve. Random misfire on my 2003 Odyssey in June went away with new (Dorman) EGR - but the misfire was back in December! Needed a new (OEM) EGR - damn Dorman crap.
Had a 98 Accord with the 6 cylinder. It had great power. Loved it. Passed it down to the kids who drove it till they traded it.
Ivan , i went and bought some of that AST 505 CRO as i have a Honda 150K using oil , not burning it ,but i think the oil ring needs degunked ...i hope it works!!
This is my round robin fix for these engines:
1) replace timing belt, water pump, and tensioner (if due, usually overdue), using the Aisin kit,
2) replace serpentine belt(s) and tensioner
3) clear out all EGR passages in the intake manifold
4) adjust valve clearances
5) replace spark plugs
6) remove and clean out the IAC valve
If greater than 175-200k miles, pull the pan, clean out the sludge and replace the oil suction tube o-ring
Always a great case study Ivan! With respect to "rich condition": you were looking at Lamda and trims which are logic based, not real time inputs from A/F or O2s. My take on why it was pulling fuel on bank 1 was because it was protecting the cat. My theory could be proven true or false by having front A/F sensors (or O2s... whatever's up front) pulled up on your data stream. It likely would have shown a lean bias - a condition misfires typically create as you know. If that had been the case, an appropriate typical response would be for the computer to ADD fuel (hence your question), but seeing the miss on that bank, ECM logic infers raw fuel is hitting the cat and it pulls fuel as you saw. Just a theory from a humble mechanic, but thinking about it, I'm pretty sure I see this relationship quite a bit with trims and misfires.
People often think if a car has a stylized "H" or a "T' on the front that they can just drive it with no maintenance. As the Car Care Nut says, "Toyotas and Hondas like their maintenance." IIRC valve adjustment is a scheduled maintenance procedure. I would say people are accustomed to American cars that have hydraulic lifters that don't require valve adjustments. (The last American car I had that I adjusted the valves was my 1963 Falcon with the 170 cu.in engine.) In the 200,000+ miles this car probably has never had this done. I always wondered why Toyota and Honda used timing belts and solid lifters as long as they did. IIRC that Camry you have, Ivan, burns a quart of oil every 600 miles because maintenance wasn't performed. Toyotas and Hondas are good cars but, they must be properly maintained. GREAT VIDEO!
Lol. As a young kid I, lacking knowledge, adjusted the valves on our 1971 comet 170. Ran like crap. American motors mechanic straightened me out.
@@gadasavideos8564 My 1976 Comet had a 302 c.i.d. engine in it and it had hydraulic valves. Many of those AMC cars had straight six engines in them.
@lvsqcsl my comet was mercury. Just happened that I went to amc dealer since it was owned by the engine guy for a race car in our town. I think it actually had hydraulic valves which I knew nothing about when I was 16.
@@gadasavideos8564 Don't feel like the Lone Ranger; I wouldn't have known anything about that if my dad hadn't shown me. Those adjustments were on the rocker arms and he would adjust those while the engine was running. With the valve cover off it would throw oil everywhere if you weren't careful. lol.
@lvsqcsl that actually how the mechanic readjusted them. I was 15 before our family owned a car .dad sold his in the 40s tobiy a house. Maintenance wasn't our forte. Rockers clicked from lack of oil. Lol I eliminated the click by eliminating the clearance. Got a new 67 ford 289. Some neglect. Added bardahl and put guitar strings down the oil passage holes to it oiling again. Knew enough then not to touch the adjustment
Sounds like CD is miss fire on start up.😂😂😂
Listening to interference patterns is an old way of spotting problems,( not a joke).
I can't wait for the update. Personally my go to test on the Honda v6 when I'm suspecting a tight valve adjustment problem. I prefer having the car stone cold. I look at vacuum when cold. It will normally be low. Maybe 15 inches mmg. Then I let the car continue to rub till warmed up. The vacuum will normally increase. To a more normal 17-18. It has worked for me every time. Especially on 3.5 and 3.2s. Can't we also look at the your first pressure waveform and tell valve sealing characteristics? Can it only be evaluated with running compression?
My honda accord 2008 v6 has same problem i spent lot of money no one was able to figure this out. I showed this video to my mechanic he said this might be not the issue on your car. I asked for value clearance he asked me to go to dealer to do it. I have 176k miles on it. It rides fine. Missfires happen only at the idle time. Once i drive everything works fine.
Yes just needs a valve adjustment :)
Interesting case. In hindsight (i know) maybe a cranking rc test, with a sync on ignition coil 1, a pressure transducer on the inlet manifold and a pulse sensor in the tailpipe might have given some valuable direction/results. Thanks Ivan, looking forward to part 2.
Cool !
Great video but just a tip about your egr statement not causing a single cylinder misfire. Thats actually not true as the ford windstars with the 3.8 and really any engine with egr flow to individual cylinders can suffer an egr misfire if all the ports are plugged except for 1. Now egr shouldnt be open at idle right but it can happen. An open egr and a single egr port thats clear can definitely skew an individual cylinders fuel mixture causing the misfire.
Again great video
Why would the valves be in valve overlap in the open position? I thought overlap only occurred in the closed position. Help me to understand this.
Just wandering if it was okay to disable the fuel for the compression test?
Remove the fuse for the CD player.
😂
My acura TL 2004 had a misfire on all cylinders also on cold starts mainly.. car has 293k miles and never had a valve adjustment done.. has new plugs and coils.. Next is the valve adjustment and if problem continues i will check into the injectors.. But hoping the valve adjustment fixes the issue.
I have chased this same code on my 2001 jeep Cherokee fired parts canon new fuel pump only thing left is an injector only misfire is on cylinder 3 167000 miles on the car it runs great sometimes when I loosen the gas cap to get gas the pressure blowback is really high
the running rich on bank 1 is do to it not fire the gas and the unburnt fuel is causing the o2 sensor to see rich. since number 1 is a dead miss raw fuel is passing into the exhaust thus the o2 sensor sending that reading to the pcm. i have seen this before. kept up the perfect work. regards from mobile daignostics in bath indaina.
But doesn't the oxygen sensor measure OXYGEN? the unburnt oxygen would also go out of the cylinder so wouldn't that cause POSITIVE fuel trims? 🤔😉
@@PineHollowAutoDiagnostics you do have a good point there.
You do have a good point there. Does that car have intake manifold runners?
Sheesh you have a hard case on your hands. Maybe we need to go towards a injector now because it too much fuel can cause it to wash the cylinder and possibly be a difference in compression. As when you took a compression test it was 10 PSI lower. So maybe a injector's sticking too much fuel into it. But I'm not there to analyze the car. I'm sure you'll figure it out if the smartest man I know and how I learn to do and get in this industry
11:40 Was it doing clear flood mode since you had the accelerator floored? Maybe it disables spark as well as fuel.
I take it regular maintenance is not part of this car's history. Hence the green corrosion on the positive battery cable. Wouldn't surprise me if the battery is ready to take a dump in that.
Adjusting valve clearances could be avoided with an efficient hydraulic lifter system, however Honda chose to pass that cost onto the consumer at a later date. Not a bad car, but there are better systems.
DAMB is better IMO like my Zetec Focus, 22 years/208k miles uses, as well as Toyota, uses.
hydraulic lifters have their own set of problems. just look at the ticking silverados.
@@PandaMan02 Overhead cam verses in block cam uses two different types of hydraulic valve adjusters. The inblock cam uses a moving hydraulic lifter that moves with in conjunction with the valve, rocker arm and pushrod. The overhead cam engine uses a stationary hydraulic lash adjuster that only takes up the clearance between the cam, rocker arm and the valve. It doesn't move other than just the clearance it has to take up. That doesn't mean that they can't have problems but it not quite the same. Sometimes it can be worse. I have a three valve 4.6 v8 in my Mustang GT and had a lash adjuster wipe out a rocker arm and cam.
@@BigEightiesNewWavemy son has a 2004 Pilot with 350,000 plus miles with no issues, same engine
Honda still manufacturers. v6. With timing belts & adjustable valves good for the dealerships.
Were the valves overly clean? Did you look at a " good " cylinders valves? Could a small un noticed coolant leak cause the problem the customer is having? I'm just guessing not trying to tell you anything you don't already know.. What is the recommended valve adjustment range / time interval. for Hondas?.
Is there a chance of some kind of injector issue? I would expect the fuel trims to show lean as the misfire happens. The whole "random misfire" history is a bit puzzling as well. If EGR is leaking through and is not being commanded, I expect that the reduced oxygen entering the combustion is going to cause a rich condition. I do not know how the EGR is distributed to the cylinders, but if some passages are plugged and #1 is still clear???
However, these symptoms match my experience with such single cylinder compression related "idle-only" misfires. I do not have suitable device for checking running compression figures, but when a compression test yields compression figures right about where they should be, everything else seems to check out fine, and the smoke machine down the spark plug hole shows smoke out the exhaust pipe, I have to blame the valves--either adjustment or simply being worn out. Usually it is the exhaust.
I have largely abandoned the compression test as a measure of engine health. I've had (what seems like) perfectly healthy engines have a 15 PSI compression discrepancy between cylinders and run absolutely perfectly. Then, like in this video, a "small" 10 PSI difference and an idle misfire.
Science and mathematics equal TRUTH
❤
Good thing is that Honda, is from when Honda's did not have modern Honda problems. Successfully, mostly, high-miles. Money's worth.
how about egr port at the intake under the big cover their known to block
EGR issues would affect ALL cylinders, but you are correct. These cars need a good long robust drive on a regular basis to keep the engine clean.
I'm from N.j. Here's how to get inspection with check engine light. Wake up at 4am and drive car a block from highway. Plug into odb & clear codes. Disconnect battery for 5 minutes and reconnect. Drive on highway for 75 miles on cruise control at 60mph( gsp or turnpike works best). Get to motor vehicle at 7am when they open. When they ask u to get out of car, shut it off- they restart and u should be good. That dam po420 code ain't got nothing on me. Rolling deep & legal with my 2 year sticker for past 6 years in a 98 Camry. Doesn't work in all cases. In NJ, u can have a rusted out engine cradle, no wiper blades, head light bulb burnt out and tires so bald that it makes Kojak look like he had hair but NJ doesn't care about that but only a cel. What a crying shame
I appreciate all the pico scope work on this, but I would have done a compression test right off the bat, and as well would have done the borescope test. 15 min max.
A running compression test is a another test that can isolate a valve train problem
Ivan, could you have found an irregularity in cylinder #1 with a leak down test? As always, proper analysis of the issue is essential.
Just wait for Part 2 😉
👍👍
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When you pulled out number 1 spark plug, you said it was wet, which was after pulling the fuel supply relay and cranking. Leaking injector would also answer rich on that bank.
What is a pgmfi relay? I don't think he pull the power to the fuel pump just power to the injectors.
if you suspect a burnt or partially seating valve. why not do a leak down test right off the bat. it would give you pass/fail info right away and resolve cylinder combustion/sealing integrity. that's my thought.
See Part 2. Leak down test showed PERFECT sealing on the BAD cylinder! I was actually very surprised! 🤔
If you had part of the air/fuel mixture blowing past the exhaust valves the O2's are probably going to read rich. I've struggled with this on several Honda's before, that just needed valve adjustments to fix crazy bad rich conditions.
Hmm, I thought with that mileage, timing belt almost due along with the other maintenance items
Plugs, valve adjustment and of course valve cover gaskets when you see oil in the plug wells, water pump, check serpentine belt, etc
I would go after timing and make sure that’s on the dot these Honda V6’s only have one cam sensor and it’s on bank 2 timing for bank one is made off of an assumption that it is where it needs to be and cause random miss fire code with no cam crank correlation codes, might also be why bank 1 is showing rich
Valve design and back cuts aren’t identical for intake and exhaust. Additionally the material they are made of will also be different because of the corrosive environment exhaust valves endure
To find a sink, could you just leave out a plug like 7 and that would show you # 7 low and you could just count the firing order? Or would that very low one through off the readings of the others?
It would definitely throw off the readings 👍
@@PineHollowAutoDiagnostics Not if you take out #7 plug! 😁
@@Runco990haha oh yeah #7 😅
Valve adjustment,?
Off topic but has this ever happened to you? I use to use oriellys alot because the staff was amazing and the product was ok (now everything is crap and I use mostly oe parts). My mother in-law has a wobble feeling when hitting the brakes, so it needed up being a warped rotor. I did the brakes 2 months ago so everything was under warranty. When she took the items back to orielly's a new guy said I did the brakes wrong. He claimed because I didn't lube the pad ears. I dont lube pad ears because the pad dust builds up in the track and its not a rust area. I only lube behind hardware, caliper piston face and pins. At first he wasn't going to do a warranty but the manager apologized. Then 2 days later (about 3 days from now) a customer called with a start stall issue. I get there and I have codes for the igf circuit (2008 toyotasienn). I hook the scope up to the igf wire and i get 2.8 volts with koeo. I start unplugging coils and the 4th coil (of course the one under the intake manifold) the volts jump to 5. I plug it in volts drop 2.8(I was just making sure I didn't move the harness when unplugging and that was the issue). The customer just replaced the coils 4 months with oriellys coils. He goes up to try and get credit on a warranty because I replaced all coils with toyota parts. The new guy at oriellys (same guy) told the customer I misdiagnosed his vehicle because the coil would smell burnt even thoughthe van was running. All those classes I took for diaging and all the equipment I bought is a waste because this guy at oriellys has the secret. he knows rotors are warped by a glance and your electrical parts are bad by a sniff. You dont even need a scan tool he comes out to your car like the k9 unit, sniffs around and bingo he knows. You got a wobble, he's superman by a look he knows. I have to call on this clown because if it was a customers that he talked to it could of caused q problem.
The rotor was warped and the coil was particularly shorted because both vehicle has no complaints after repair.
Injector is bleeding down on cold soak. I would do a borescope on cylinder one and a fuel leakdown. Looks like carbon build-up on valve as well as a lean condition. That engine has had valve clearance issues. However, looks like it is pinging on acceleration.
Lower compression = incomplete combustion?
With scan tool you can disable injectors.
I use the MAP data on these and it will run a little rich on that bank with the worst valve. The seats wear out just a little and tighten up the lash.
Hondas never break, they only need repairs.
To me... it looks like the seating surface on the left valve is dull compared to the right valve, which is nice and shiny. Needs some more lash clearance.
Your abilities and scope are both impressive....BUT-
If I encounter a 200k mile honda, that has never had a valve adjustment, especially one with random idlespeed misfires, it needs a valve adjustment. Whether it is convenient or not.
As the measured valve clearance approaches zero, the times a valve begins to leak or not depend more and more on the relative temp of the valve-vs-head..exhaust valve length changes with temp..which depends on throttle position...acceleration or deceleration, etc.
If the clearance would measure 0.0005", it is too tight, but will seal during your cranking test. Then leak as soon as the valve heats and lengthens 0.001" and fails to close completely. And will be burning away at this time.
Another factor- I have seen honda fours and v6s with many fewer miles that have very loose valve to guide clearances. Just loose, worn out. This will cause valve to seat contact to be less predictable. Having ample valve clearance matters even more now- if the clearance is almost zero, and the guide can no longer be trusted to center the valve head in the seat, leakage could occur randomly, depending on temperatures, rpm, valve spring vibrations...etc. it just becomes uncertain.
A valve adjustment might save the guy head removal or replacement in the near future, which might send an old, otherwise good car to the junkyard, depending on the owners budget.
That picoscope is so useful and cool, but doesn't replace maintenance that you just have to do. Hondas with screw and locknut type valve adjustment NEED that. Buy something with hydraulic lifters if you don't like that. Or a toyota with shim type adjustment...still needs it, but goes a long long time.
That slight difference in compression could very well be stuck or almost stuck rings, too.
A leakdown (differential) compression test would be interesting, but most car people seem to never do that. It also will not show a valve that barely closes during the test (when cool) but will leak when the exhaust valve is 1100 deg f under a load, when it really matters.
Burn, baby, burn! It'll never seal again.
It doesn't seem like 150 vs 160 is enough. When did he start having the problem? It doesn't make sense to me that the problem would start and get worse after a bit of running. If the valve lift was heat related, why wouldn't it be immediate if the car was warmed up? How do the exhaust gasses change? Weird.
O2 Sensor bank 1 is bad even though it's not throwing a code. It may be sending erroneous data to the ECM telling it of a lean condition so the ECM is adjusting rich. OR this thing has 205K on the clock and those are the original injectors and they are leaking inside the cylinder adding more fuel than the ECM expects if the fuel is leaking into the cylinder when sitting as well, it may have damaged the rings on the piston causing the low compression? All I got.
Here's why bank 1 is running rich/taking away fuel. Computer is injecting right fuel for the amount of air. During the intake stroke oxygen entering the cylinder is displaced by the inert exhaust gas because the tight exhaust valve that creates a leak when engine is hot. You know during induction stroke there's lower pressure in the cylinder and higher pressure in the exhaust. So lower pressure inert exhaust gas enters lower pressure cylinder through the valve leak and displaces oxygen(which is 20% of "air"). Now even if we got proper injector, injecting the correct amount of fuel, the problem becomes that oxygen has been replaced by inert gas. And now the fuel-mixture in this cylinder is rich and that's why the plug was "wet". But the bigger problem is that oxygen sensor sees "less oxygen" in the exhaust ordering the computer to cut fuel. This mimics leaking injector problem , but its not. This would make other cylinders on the bank run lean , which can be seen on secondary injection waveforms. But the important one here was , the pinpoint test for finding tight valves would be comparing the misfiring cylinder pressure waveform to non misfiring pressure waveforms and compere exhaust valve opening/closing times. The tight valve would open sooner and close latter than the non misfiring cylinder.
Did you compare the waveforms and see a difference in valve duration? 🤔
By cranking with the pedal down you should be activating clear flood mode, so you shouldn’t need to remove the relay, no?
Needs a valve adjustment but that’s just my guess I have not actually watched the video! Arm chair diagnosis( please someone let me know if I’m correct 👍🏻, In my experience I’ve only ever fixed a random misfire code on a Honda of this generation with a valve adjustment that goes for any Honda product with a 6 cylinder
The computer assumes equal air flow through both banks, and simply sends the appropriate amount of fuel to each bank to account for half of the mass air flow reading. If one bank loses volumetric efficiency, the computer will send too much fuel to the bank with lower airflow (rich) and not enough fuel to the normal bank (lean). Low volumetric efficiency on a whole bank can be caused by catalytic convertors, and I was honestly thinking that might be the issue, but it looks like the exhaust stroke was pretty clean on cylinder 1, so that hypothesis was wrong.
No MAF on this Honda 😉
Ivan if the idle was acting up because of carbon build up could you inject some water when hot to clean up the carbon build up? This is just a question I am not suggesting that I think carbon build up is the problem.
It was my understanding that tight valves would be an excited employee (open early and close late) and a loose valve would be a bad employee (open late and close early). Therefore, a tight valve would increase valve duration and a loose would decrease valve duration. With such defined valve events, I think you should compare to the known good. What’s your opinion on that?
Also I wrote a program for piston overlays and it’s free on my channel with a demo video. I couldn’t find a free one, so I wrote one myself 2 months ago. I’d be interested in your feedback. I’m not as good at doing it in my head like you lol
Good video. You like using pico 6 over pico 7?
I like Pico 6 😊
If you not take it apart yet do you if you did a F I C on the motor to decarb the motor I herd high compression also could be carbon build up
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