3.6L GM Misfire Nightmare - Why No Check Engine Light!?!?
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- Опубликовано: 11 июл 2024
- The parts cannon was fired at this 2014 Chevy Impala 3.6L in an attempt to fix a misfire issue on this car by not just 1, not 2, but 3 previous shops. It's time to put it through our diagnostic process here at GoTech and get to the root cause of the problem.
Learn Relative Compression - • What's The Most Effici...
GM 3.6L Timing Problem Overview - gotech.com/learn/what-is/gm-3...
GM 3.6L Timing Chain Diagnosis - gotech.com/learn/how-to/gm-3....
How to Test a GM 3.6L Timing Chain - gotech.com/learn/how-to/test-...
How to Replace a GM 3.6L Timing Chain - gotech.com/learn/how-to/repla...
0:00 Introduction
0:21 The Complaint
1:57 Scan Tool Data
3:27 Relative Compression Test
4:24 Engine Vacuum Test
6:28 Cam/Crank Correlation Test
11:20 Conclusion 
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YOUR DIAGNOSTIC PROCEDURES ARE MOST LOGICAL APPROACH EVER. THANK YOU FOR THAT.
First time I watched one of your videos. Great job 👍 It's good to know there are mechanics out there that don't just load the parts cannon and hope something sticks.
Thanks!!! Welcome to the channel!
Mike Becker, Senior Instructor
You rule, brother! Your channel is what makes RUclips awesome.
Hey Dave, thanks brother!
Mike Becker, Senior Instructor
This is actually really good information. My wife's cadillac has this exact same problem and the previous owner changed every part under the sun. Still randomly runs like crap, found the timing chain was stretched
Welcome back Mike. Excellent video as always.
Thank you thank you bud! Appreciate you watching!
Mike Becker, Senior Instructor
Dude you are the man - great diagnosis, you know your stuff as I have this engine and what you say is gospel. Greetings from Australia!
Those other shops that claim to be professional auto repair shops need to attend some classes at RUclips University. I just found your channel and your experience and knowledge makes it one of the best I have seen.
Wow thanks a lot! Welcome tot he channel! :)
Mike Becker, Senior Instructor
Great diagnosis! Thanks Justin for sharing your known good waveform.
Hey Bart, thanks for watching!!!!
Mike Becker, Senior Instructor
Well explained vid as always! Always learn something watching you. Thank you so much!
Thanks for watching! Glad you picked something up from it!
Mike Becker, Senior Instructor
As always, great video Mike!
Thanks PJ! Hope all is well :)
Mike Becker, Senior Instructor
Well done brother. Win for the scope again.
Clear and concise. Way to go!
Thanks for watching Johnny Blue!
Mike Becker, Senior Instructor
Very useful video. Pleasure to watch professional work.Thanks a lot
Thank you very much Mike! Appreciate it :)
Mike Becker, Senior Instructor
Awsome detailed videos like always 👌
Hey Henry, thanks for watching!!
Mike Becker, Senior Instructor
This is an awesome channel. Thanks for sharing.
Thanks for watching! Appreciate it :)
Mike Becker, Senior Instructor
Always a pleasure to learn from you Mike!
Thanks a ton!
Mike Becker, Senior Instructor
Whewwww, just what happened to mine but the front bank… awesome, wish I could pull and see this like you did, props and thanks for confirming as always 💪🍺🤙
Hi,
Thanks for watching and reaching out!
~Ryan Wilsing
Great Work On The Diagnosis, Either Way Chain Stretch Or Phaser Problem Doesn’t Matter Which Is The Problem, You Can Confirm Once You Disassemble If You We’re Doing The Job. But Your Diagnostic Techniques Put You On The Exact Path To Finding The Issue. Awesome Work.
Exactly! And we didn't have to pull the cover to diagnose it. Thanks for watching bud!
~Mike
@@GoTechTraining Your Welcome!
Pico scope discovers the problem!
Nice Find Mike.
Hey Mike, thanks man!
Mike Becker, Senior Instructor
Nice straightforward diag.
Nice diagnosis Mike!! I agree!
Hey Bob, thanks for watching! Hope you are feeling well!
Mike Becker, Senior Instructor
Great video Mike. Resources are very helpful.
Thanks a ton!
Mike Becker, Senior Instructor
keep in mind that the 3.6 tends to slide or spin the crank reluctor gear, it get loose and will cause both banks to create a correlation code. but if it is only one bank, most likely it is a timing chain issue.
Hey, thanks for watching! Yeh, i've seen that TSB for reluctor shift. Yeh, I agree!
Mike Becker, Senior Instructor
as always another awesome video
Thank ya much!
Mike Becker, Senior Instructor
Great diagnosis.
Thanks so much!
Mike Becker, Senior Instructor
Thank you for the helpful info and explanation! I’m still trying to learn the cam/crank correlation waveforms… we’ll moreso finding known goods. It takes me forever to locate those! 🤦🏽♂️
Hey Greg, thanks for watching! Check out the known good waveform library group on Facebook. They have a lot there!
Mike Becker, Senior Instructor
Keep changing that oil and check it every 2000 miles, and say a prayer 3.6 owners!!
Another great one. Thanks a lot.
Thank you for watching!
Mike Becker, Senior Instructor
😮- Thanks for this info!
Crazy world we live in today were even a timing CHAIN doesn't last! Great diagnosis as usual, Mike! I should've bought a scope years ago, but I keep buying toys, like a paramotor, and a supercharger for the 5.3 Silverado, lol. :)
For sure Smitty for sure! Ohhh a supercharger for a Silverado is way more fun than a labscope!
Mike Becker, Senior Instructor
@@GoTechTraining Indeed it is! 😁
If you knew how GM puchasing sourced parts ie low bidder plus an additional demand for another 7% discount you would not be so surprised.
My friend has a Cadillac with this engine. He does all his own work since he owns a lift and cradle. At 100 G he changed everything involved with the timing with a kit he purchased. He loves his Cadillac and said this was bound to happen.
Great video, thanks!
Hey Russel, thanks for watching!
Mike Becker, Senior Instructor
Thanks Mike. Appreciate it.
Thanks for watching Petar!
Mike Becker, Senior Instructor
great video finding the problem without getting your hands dirty
Hey Gonz Garr, thanks for watching!
Mike Becker, Senior Instructor
Great video!!
Thanks for watching!
Mike Becker, Senior Instructor
just curious if u would have gone the route u did if u were the first to touch it, as always great explanation and hope ur back soon, happy dads day, enjoy!
Hard to say for sure. The diagnostic process should be the same though. That's what makes for repeatable high level diagnosis.
Mike Becker, Senior Instructor
Mike! you make auto work simple
Hey Francis, thanks for watching! The camera makes it look simple :)
Mike Becker, Senior Instructor
Good job sharing
Thanks for watching!
Mike Becker, Senior Instructor
Cool video Mike! Couple questions: how did B1 chain stretch but not B2? I don't believe that a 6 degree stretch would cause a -14% fuel trim. My bet is that a pin sheared on one of the cam phasers on B1, which would NOT shift the cam signals, but would shift the actual camshaft! Impossible to diagnose without physical teardown unfortunately. Have you seen my Hyundai from Hell video? 👍🙂
Hey Ivan! Thanks man! So I've heard that B1 has an oiling issue. You're right though, tearing down will be on the only 100% way to know the root cause of timing misalignment and the breathing issue. I haven't seen it, but I will look for it now! Hope all is well!
Mike Becker, Senior Instructor
Bank 1 always wears the most, and sets codes first. Don't know why. But definitely a pattern failure.
@@briannackers963More heat on the firewall bank would be my guess
I’m no mechanic but have 3.6 and have heard that the PCV can clog and cause issues on bank 1
Great diagnosis
The old vacuum gauge doesn't lie 👍
Hey Atiq, you are right! Any idea what good spec is?
Mike Becker, Senior Instructor
@@GoTechTraining 18 to 22 inches of mercury
Providing the general health of the engine is good
I've heard those numbers before as general rules of thumb. Is that specific to the 3.6?
Mike Becker, Senior Instructor
@@GoTechTraining Hi Mike
Thats just fundamentals
We have those 3.6 motors here in Australia fitted to GMH..General Motors Holden
At least yours are all RWD in Australia, right?
Mike Becker, Senior Instructor
I had this issue with a 2007 Cts 3.6 years ago ...Timing Chain stretched and it actually had a recall on it
i noticed you didnt use your cursers. have you ever did the math on miliseconds to degree conversion for us that have just a basic scope? as always thanx mike good to see you again!!!
Hey Richard, no, the math, with cursors and all was done off camera. I didn't show it here for 2 reasons...save time and the amount it's out doesn't reallllllllllly matter. Out of time is out of time, right?
Mike Becker, Senior Instructor
Great brake down on this 2013 Chevy equinox 3.6 V6 mine has never set a code either I've had this issue for about 50,000 miles never gotten worse ironically runs out fine enough to not care but lightly pops out the intake when shut off really have to listen for it to know but I'm in the great debate myself put money out to do timing or driving until it dies 241000 miles we will see it would be fun to fix but time is not easy to come by.
bring more study cases the journy is very useful especially the live diagnosis
Hey Khasem, sounds good! We'll do our best to share them!
Mike Becker, Senior Instructor
HI!!!!! I have a similar fault in a 2012 cts 3.6 only that you would have to add excessive, exaggerated fuel consumption to mine, my mechanic scanned it and marked 2 values in "misfire current in cylinder 2", I do not have a check engine light . Unfortunately for me here in Mexico and specifically in the small city where I live there is no one who does an excellent diagnostic job like you, they recommended that I change coils, injectors, etc... But I haven't done anything because I don't want to spend money and getting annoyed with the car, I love this car to transport my family, it is the version that arrived in my country with 19-inch wheels and Recaro seats.
Nice video sir. Yes, those engines do have timing chain issues.
Hey Luis, yes the do, big time! Thanks for watching!
~Mike
@@GoTechTraining you're welcome
Timing chain issues if. You don’t change the oil enough. 5000 miles max in these engines. Don’t belive the 10000 mile crap. Use full synthetic. Also the tensioners run on oil pressure. Keep oil full. Avoid overheating the motor. Check the pcv often.
This sounds like this issue I've been having on my impala, and the chevy dealership shop told me I need a whole new transmission, I took it to a transmission shop and they said the scan showed up fine, I've been in denial that it was the chain but now I'm almost positive it is but I just passed 200k miles so it's probably long overdue, thank you for this video
I had a P0017 light. I also had a few rich codes on both banks. I changed the cam sensors on bank 2 and the Exhaust VVT(I think) solenoid and amazingly all the codes went away before I even asked to see the codes in the scanner. Eventually, in a few weeks, I'm going to change the other banks cam sensors and the other 3 VVT solenoids. My 3.0 2010 Equinox has 155K miles and I've always used Mobil 1/Amsoil/Pennzoil Platinum Synthetic with regular oil changes and a FilterMag on the filter. I'm the original owner. I have a slight stumble at idle so this video was great. I don't have a sophisticated scanner to check the readings like you did in this video and I do know that eventually timing chains will probably have to be done. Not something my wallet is looking forward to.
Hey Chris, thanks for watching! I feel for your wallet. Timing chain jobs are never easy on it hahah!
Mike Becker, Senior Instructor
did you have to get a cam relearn procedure done?
@@XPSnowblowing I have not. I've just left it. Still runs good just not at idle. It still gets 25mpg on the highway doing 75+mph. Just passed 177K miles last week.
I have a 2011 cts 3.6 with 145k on it and about 6 months ago started having random multiple misfires on start up on high idle only, once comes of high idle smooths out. did some reading and found out about timing chains on vvt gm 3.6 engines spent the money at a reputable shop and got chains done. Got it back two days later. The same problem was there. asked them to diagnose the problem and they suggested coils and plugs which I had them do and no difference. they tried a seafoam drip into the direct fuel injection system as it's not the standard fuel injectors I'm told, was given it back after a week and told the only option was to pull motor apart which they couldn't be sure of what or if they could find anything. so, I took it back. looked into possible cam shaft actuators being plugged with sludge affecting oil pressure to phasers. trying marvel mystery oil and seafoam in oil to breakdown anything in there first, motor is quiet on running no noises from chains at all. here is the strange part I park the driven into my driveway up hill and upon starting no misfires, park it backed in and downhill and misfires everywhere p0304 p0301 p0306 not all one bank both banks different times, like I said been going through this about 6 months but the oil in the different levels in the pan tilt tells me something. don't known if I want to change cam shaft solenoid's or just remove them and clean them as I've watched a video on that anybody had anything like this on their GM 3.6 i would appreciate it thanks.
Thanks!
Woah thanks so much Anselmo!
Mike Becker, Senior Instructor
As soon as the scope came out I already knew Mike will come up with a conclusion! And let's not forget, not even 1 bolt has been turned! Awesome stuff Mike 👍!
Hey Nick, thanks for watching! To be fair, I did need to disable fuel. So I did have to take one thing apart, hahahah!
Mike Becker, Senior Instructor
Hi Mike: is the Bank 1 cam/ckp correlation signal capture is under cranking or running? with the vvt solenoids unplugged? thx
Our lord and saviour Micheal is back again!
This week I had a 2012 Honda 2.4L with a cylinder one misfire, moving the spark plug, coil and fuel injector to number 2 did not move the misfire.
I did a in-cylinder waveform as well as a regular compression test and noticed the compression was slightly less than the other cylinders. Intake pulls where slightly less than cylinder 2. I wanted to perform a valve adjustment to see if the compression and intake pulls would come up but customer declined the work booooo
Hey man, thanks for watching! You give me too much credit lol! Too bad you weren't able to get into it. Capturing those before and after are always fun!
Mike Becker, Senior Instructor
Hi Mike: Can you explain how Timing chain stretch affect the fuel trim to go negative? is it because of the intake valve open late caused low vacuum pull (less air = rich air fuel mixture?) Thank you
Thanks
Thanks for watching Hot Rod!
Mike Becker, Senior Instructor
This is diagnose in your style👍. What do you think if use a in cylinder pressure transducer, would you see anything on valve events.
Hey Ivan, thanks for watching! Hmm not sure if you'd see it. I chose not to because I had a bank of misfires, not single cylinder.
Mike Becker, Senior Instructor
@@GoTechTraining Thank you I was just curious, because it was so slightly out of timing
as usual very very good only problem i have is wish you had a new video every day. one test not sure if you have done is testing the APP sensor. been working o n a 2007 buick lacross finally got it fixed today but would like to know more about testing them
Hey man, I wish we could do a video every day too...it's hard with all our responsibilities. Not sure the APP would be causing these issues as they are bank/bank differences. The APP would likely affect the engine as a whole.
Mike Becker, Senior Instructor
@@GoTechTraining what I meant should have explained better wish you could do a in-depth diag on GM app. I just finally fixed one. Got 2 bad app sensors 3rd was the charm but would like to see if there was a easier or better way to diag
Ahhhhh sorry man, misunderstood. Honestly, a scope is probably the way to go. A volt meter isn't fast enough and the scan data can lie. I would scope the signal wires, usually there's 2 or 3. They should look like an X. If there's a 3 signal, usually they scale at a different voltage scale. Slowly move the pedal and look for inconsistencies in the signal.
Mike Becker, Senior Instructor
the replacement app was a dorman which didn't work wouldn't work at all. so oreilly sent out another one in the mean time i called the tech line for dorman to make sure i wasn't missing anything. when the second dorman one arrived i installed and before even starting it up called dorman and we went thru all the test with scope dorman again said voltage low but try it anyway. went one day set codes for app again got it back called dorman checked it again voltages low dorman said get a oem app and lets check it installed the oem voltage going in good voltage going out low but some better. he said try it and see customer left runs great the difference in the 2 app sensors was not the voltage that caused the problem it was the signal on the dorman was choppy like it was pulse regualted the oem was a smooth line guess signal was better with oem dorman said mark that one where they can check to see whats going on
Can you trust scandata for these issues? Camshaft desired vs actual PIDS? I've had a few low power complaints where I looked at those PIDs on a test drive and they showed perfect. This would "rule out" timing issues in a super quick and easy test. But I always had a slightly uneasy feeling. Scandata is not that same as looking at a scope ... but the ECM IS looking exactly at what you're looking at with that scope capture so I would THINK camshaft desired/actual PIDs SHOULD be trustworthy...? Now if physical timing is off and the ECM is able to correct with VVT action then it would look good but I would think it should show at _some_ point in a drivecycle...? Or maybe VVT could mask it enough that you might not notice. Anyone have experience with scandata vs actual scope captures on these issues?
Awesome video, and appreciate you sharing. Do have a question, I’m sure many of us have seen and driven a vehicle with cam correlation issues. Can’t argue with the data you’ve gathered, but you’d think a vehicle that is stretched enough would have noticeable issues like what you experienced
Hey George, thanks for watching! It's tough to say how the vehicle will react especially with the ability to phase cam timing. If base timing is out, could VVT pull it back in to make it run ok? I guess it would depend on how it was out and how far...and on the strategy of the PCM too.
Mike Becker, Senior Instructor
i replace timing chains on a 3.6 malibu, timing marks were right previous to replacement, and custmer replaced cam and crank sensors, and actuator solenoides for timing. cant remeber code number but was related to the bank closed to the firewall, chain was not that tie. i did some upgrades recommenden by tsb.. and problem went away. unfortunately i did not recorded any scope patterns previous or after the repair was done.
Glad to hear you got it fixed up!
Mike Becker, Senior Instructor
Heyy how did you hook it up to test the vic of it did you hook it up to thr pvc
What role does the VVT have in all of this if any? Thanks
hi i have a 2009 audi a4 2.0 caeb engine
having misfire on piston 1 and 4 only on high idle 3000 RPM +
replaced injectors same replaced coils and spark plugs still same checked compression and all good what can it be thanks 🙏
Very nice work Mike. If you used a pressure transducer in the vacuum, would you have seen the problem doing an in cylinder pressure transducer reading? I haven't picked one up yet. I dont seem to use the Pico as much as I thought I would. Happy fathers day Mike!!
Hey Mike, happy Fathers Day to you as well! So, the reason I didn't go in-cylider is because I was chasing a bank misfire and not a single cylinder. Had it been single, I likely would have gone in cylinder. Not sure if you'd see it though, valve opening, especially intake is hard to see.
Mike Becker, Senior Instructor
@@GoTechTraining Oh right. That makes sense. You would see 4 strokes, not each cylinder. I see them being used to test for head gasket leaks now too. Getting too advanced for me. You're def. great at your job sir.
Like with any tool, the PICO scope and transducer have their uses. They are great when you need them and dust collectors when you don't. I highly doubt anything is too advanced for you if you spend a little time with it! I've seen your work...Porsche Mike...it's impressive!!!
Mike Becker, Senior Instructor
@@GoTechTraining Thanks Mike. I had a great teacher.
Teachers, I can only take a fraction of credit for helping people fix cars. There are so many great people out there making videos :)
Mike Becker, Senior Instructor
My 2011 camaro 3.6 same nightmare
Grasias
Gracias Martin!
Mike Becker, Senior Instructor
Just had one of those in my shop with a single cycle miss an they threw the cannon at it instead of testing.. cylinder was getting washed out.. ... they don't know if it was ps/gs controlled but I'm bet it was grounding since it was a crash car.
All I can say is WOW. My brother owns a new 2016 Cadillac CTS 3.6 L (30K mi) and the dealer can not find anything wrong with it. It also threw a Bank 1 Lean, check engine light (CEL) at 8 K miles. I see the miss fires on 1, 3, 5 and we checked for vacuum leaks, swapped coils etc. The vehicle has a K&N cold air induction we installed just after the CEL issue. The dealer would not fix the vehicle unless we remove it. I said no way. The air cleaner should also cause the same problem on the other bank as it is a true dual exhuast & manifolds. I now suspect it may have a defective timing chain as well. What are the odds of that with so few miles especially on a brand new vehicle. The dealers answer was: "Well just drive it and let it brake in". The vehicle is notorisly bad for random CEL's. Now with over 30K miles we just unhook the battery and let the codes clear. I'm sure it will get worse as time goes on even with Mobil 1 synthetic oil from the factory. And yes you can sense and feel the misfire murmur every now and then.
Hi John,
Wow, Sad to hear a dealer say "let it break in"
Hope you eventually get it fixed! If so let us know what the cause was.
Thanks for checking out the video and reaching out!
Ryan Wilsing
I have to ask; where is this dealer? I want to be sure to avoid.
2016 isn't a brand new car
I’ve got that engine with 160,000 miles. I never came close to driving it like I stole it. It doesn’t even burn even a quart every 5000 miles. Was yours ever driven hard? Seems to me that can stretch a chain.
I never understood why they call them cold air induction when they are located in the engine bay. Stock induction takes ambient temperature air from the front grill. So putting an overpriced filter in the engine bay makes the air colder? Explain to me.
I had a bank 1 problem on an escalade 6.2 it ended up being a ground problem on the block no comparison to a 3.6 b2 kept ground bank 1 didn't.
SUBSTANTIAL Go Tech Mike Becker
Great tutorial brilliant video thank you very much helpful video take care and have a great day Go Tech Mike Becker
From Nick Ayivor from London England UK 🇬🇧
I have thus engine on my alfa romeo, it's timing chain issues caused by gunk in the engjnd caused by the PCV valve getting clogged. keep ckeaning out the PCV valve and change the oil regularly.😊
Increasingly I’ve come to realize from my experiences, that as highly sophisticated as the computer controls are on modern vehicles, often times problems that should set a code, do not, because they are not within the parameters to do so. I was surprised that vehicle did not set a cam/crank code, being off by 6 degrees.
However, one thing I’ve long done when looking at PIDS on any vehicle with VVT, is looking at the desired and actual degree position for each camshaft. I would imagine that you would be able to identify that bank 1 was retarded by looking at that data.
Hey JPJ Auto Tech, thanks for watching! From what others have said, at production calibration this car would have coded. After the reflash, parameters were widened. As far as actual and desired, that's tough to say. I'll have to see if I have that data. If I do, i'll respond back what I see.,
Mike Becker, Senior Instructor
It would be interesting to see, if you do have that data. I really appreciate the content on this channel, a lot of very good in depth info here.
I know Chrysler do have that data on my launch but I"m unsure about GMs.
I know Ford shows it too. Honestly though, i'm just not sure I can always trust that data. I haven't run into an issue with cam/crank correlation specifically, but scan tools are known to lie to us...and if I'm quoting a $3,000+ job I feel a lot better about seeing the pattern on my scope. Just my 2 cents 😀
Mike Becker, Senior Instructor
Oh I totally understand wanting to have the highest degree of certainty before making the final call on a high dollar job like that, I’m the same way. But if my thinking is correct, the scan tool data would at least be able to help you narrow down the problem quicker. Then you could verify with the scope.
And my understanding has long been that generic OBD2 PIDS must be accurate, with no substituted values allowed, as in enhanced mode. If I remember correctly, I believe a 3.6 Jeep Wrangler I worked on earlier this year had VVT data in generic OBD2 mode.
I have 215k on my 2012 Impala and I have this kind of weird random stumble at idle or slowing to a stop.
Dont see any cylinder misgires though when i scan it.
Starting to have misfires on my 2013 Cadillac XTS with 98865 miles. 🤦🏽♂️ Cylinder 5 is having the most misfires though. I was only intermittent at idle. But now I can feel it stutter when I drive. Cylinder 5 is the worst at 51 misfires. 2 is the next bad but at only 6 misfires. Then 3 has 4 misfires, 6 has 3 misfires Then 4 has 2 misfires and 1 only has 1 misfire. 😭🤦🏽♂️
Hey Jason, that's not good! You could always try a set of spark plugs first, if they haven't been done. They are just about due for maintenance anyway.
Carbon on the valves... throttle body
Nice
Thank P Hil!
Mike Becker, Senior Instructor
Hi Mike How is it possible to get a misfire on deceleration? So this engine is not an interference engine or 6 degrees is not enough to bend the valves?
Hey Carl, I'm told these are inference but they seem to be pretty forgiving.
Mike Becker, Senior Instructor
Rock auto fridge Magnets! hell yeah brutha!
Hello Mike, I came across this video and I've been searching for a solution on my own to fix my P0302 misfire on bank 2 I replaced spark plugs and coils with hopes of a fix and still coming up with check engine light. So in conclusion I will need to replace a timing chain?
Hey Mario, usually if it's a chain issue it will affect the entire bank, not just one cylinder. What about injectors?
Mike Becker, Senior Instructor
@@GoTechTraining Thank you for replying! Yes only on 1 cylinder, cylinder 2. I was thinking I heard any cylinder but you clearly said 1, 3 and 5 and entjre bank /half the engine. Do you recommend replacing or high pressure cleaning? I have seen a few people use an over counter gdi and valve cleaner with success. Any Recommendations are appreciated and thanks again.
I had this exact issue in my Holden Commodore SV6 2011 (Australian version of the same engine) and it turnned out it was the oil I was using, I used a nulon 10w40 and it developed intermittent misfires, especially under light load, never did it while warming up. I changed the oil to Mobil1 5w30 (as recommended) - and only because I got a good deal on the oil, and I noticed the issue went away. Bizzare, I think somehow the different viscosity of the oil was affecting the valve timing causing misfires? - the errors logged always showed 'partial misfire cylinder 1' (cant recall code) but never tripped the check engine light. Replaced plugs and coil pack but still did it. That was back when the engine had 30,000km on it and it now has 210,000km on it with no misfires since.
correct oil is 5 40 though?
Says 5w30 on the oil filler plug@@ItachiUchiha-lr3yr
My gmc Acadia was a lemon. I know some people have no problems with the 3.6 though.
Was the vacuum transducer captured while cranking?
Hey Bart, that capture was taken at warm idle.
Mike Becker, Senior Instructor
dont change the oil tensioners wear out
Hey Thomas,
I agree, these engine have had a few oiling issues!
Thanks for reaching out!
~Ryan Wilsing
Strange that one is worn/stretched more than the other. Maybe guides/tensioner problem. Either way a timing chain K I T will fix it. Thanks Mike.
It is strange for sure Terry! I've heard that the back head has an oiling issue, lack of lubrication promotes wear.
Mike Becker, Senior Instructor
Scottie said it's the timing chain 😂
I have 2012 impala and the nightmare code p0351 we tried everything but nothing is working i get the feeling this is the problem too.
it MIGHT be a cam phaser problem too.
Would it not be more prudent to rule out an exhaust restriction first, I lean that way due to reduced intake pulse on that bank?
Hey Steve, I forgot to mention that the previous shop had done a back pressure test with near identical readings bank to bank...but looking the problem, a basically no load misfire, an exhaust restriction doesn't make much sense. Typically you'd see a problem get worse as the engine heats up and under higher load situations because it can't breathe.
Mike Becker, Senior Instructor
@@GoTechTraining thanks for the reply Mike.
I was going that direction based on the relative compression results.
How do
👍
How do you measure vacuum pulls?
In this case, I hooked a PICO pressure transducer into the brake booster hose. Reading was taken at warm idle.
Mike Becker, Senior Instructor
@@GoTechTraining Interesting, thank you Mike
👍👍👍
Do you think this problem is at least partly due to lack of maintenance/extended oil change intervals?? From what I've seen on these engines it's a good idea to change the oil every 5k miles religiously regardless of what the computer tells you to do to avoid any timing chain issues. Also checking your oil frequently to avoid running low on oil between changes. I wonder if that played any role in this issue?
From everything I've research on this engine yes oil changes are critical
👍🏻👍🏻
👍👍👍
👍👍
Thanks Richard!
Mike Becker, Senior Instructor
Let me hear the sound of the engine cranking and I will tell you exactly what is the problem. As soon as you said it was weak on one bank I knew it was a timing chain issue.
Good ears!
Mike Becker, Senior Instructor
Everyone knows GM used substandard bicycle grade timing chains on these engines. So need for a diagnostic code. Anyone who wants a good 3.6 capable of going the distance should get the 3.6 Pentistar.
Just asking. How much roughly would that job cost? Lmk
The parts alone w/ no phasers are like 800 dollars, if you replace 1 phaser does another 700 dollars or more.
Hey Jeremy, $3,000-$4,000 seems to be the average pricing for a chain and necessaries to be replaced. Adding phasers adds a lot of cost.
Mike Becker, Senior Instructor
@@GoTechTraining how many hours labor do you think that is
12-ish. The quote may include more time for certain things. Depends on how the shop bills it.
Mike Becker, Senior Instructor
7:30 .... Hear me out:
On the left side chart --- We know that from the back side of your yellow exaust pulse-- over to the back of the next yellow exaust pulse is 720 Degrees, right -- (two full revolutions of the crank to get the Four strokes).. There are 30 crank pulses in that 720 degrees. That means that each crank pulse is another 24 degrees... And we seem to be just about a full crank pulse off from the known good...
crank sproket = 30 teeth
idle sprocket = 33 teeth and 22 teeth
cam phaser = 40 teeth
So each crank tooth is worth 12 degrees if it jumps a tooth (360/ 30)-- So we would actually have to jump 2 teeth at the crank to get our 24 degrees off that we are showing-- but then that would show up on both banks. (so it did not jump teeth on the crank sprocket)
If you jump a tooth at the cam phaser (360/ 40) it would be 9 degrees off of the CAM signal. but the cam only spins once per every 2 RPM of the crank. Which means that a jumped tooh at the cam phaser would only be 4.5 degrees off of the crank signal. So for it to be 24 degrees off as the signal shows-- the cam phaser would have ad to jump 5 teeth... but that would likely have made it run much more terrible than it does. (so it likely didn't jump teeth at the cam phaser either)
From what I can tell--- the only thing that logically makes sense, is that the chain jumped a tooth at the idler pulley on the bad side-- and that's how we get close to a full pulse/ notch in the signal --- but not quite. And that's because the crank sproket has 30 teeth, but the idler has 33 teeth--- so they aren't quite exact; and that's why we don't show our signal being exaclty one notch off, as it would if we had jumped a tooth at the crank.. It also explains why we only see it on one bank and not the other.
If you're going to pull it apart, I really would love it if you could spin the crank around and line up the timing notches and triple check exactly where it is off... maybe even get a protractor and show the exact degrees.
I'm thinking there will be a tensioner broken loose and that idler sprocket jumped one tooth on the bad bank. But hey, maybe I'm wrong and it's just stretch... but I personally don't think so. It's off by 20 to 24 degrees.. haha.. cheers.
Hey Calholli, I love that this video got you thinking! So, the math is a bit incorrect here. When figuring out pulses, you want to track the ignition coil event, in this pattern the blue trace. That is 720°. That crank reluctor wheel is a 60-2. 58 teeth with a 2 tooth gap. That crankshaft spins twice per 4 cycles. Meaning moving one tooth would set this back 6° of crankshaft angle. 360°/60 teeth = 6° per tooth. Again, I really love all of the time and thought you've put into this. Shows you're passionate about the industry!
Mike Becker, Senior Instructor
@@GoTechTraining Oh I see now, at 7:10 ... the blue at the bottom, is the sync... It wasn't on the next chart, so that threw me off.. I thought those cam signals were showing full rotations of the crank, but that must simply be showing intake from one cylinder to the next cylinder.. Ok, I'm with you now.
Awesome! The more you know, right?! 😃
Mike Becker, Senior Instructor
Imagine that, a GM 3.6L that needs timing chains. I just got my wife's enclave timing chains done. $3300😜
Imagine that ;) Sorry to hear that, hope that Enclave runs for a long time for you!
Mike Becker, Senior Instructor
Parts cannon working OK.
Hahha for sure ;)
Mike Becker, Senior Instructor
i think mine has timining chain stretch🥺
It is common on these motors, does yours have a slight misfire like this vehicle?
~Ryan