3.6L GM Misfire Nightmare - Why No Check Engine Light!?!?

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.

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

[sambitar]

YOUR DIAGNOSTIC PROCEDURES ARE MOST LOGICAL APPROACH EVER. THANK YOU FOR THAT.

[thevictim]

Those other shops that claim to be professional auto repair shops need to attend some classes at YouTube University. I just found your channel and your experience and knowledge makes it one of the best I have seen.

[macncheese]

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

[atiqkhan]

Great diagnosis
The old vacuum gauge doesn't lie 👍

[TheOnespeedbiker]

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.

[djosbun]

You rule, brother! Your channel is what makes YouTube awesome.

[prospexican]

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.

[edtillier]

Keep changing that oil and check it every 2000 miles, and say a prayer 3.6 owners!!

[glencoughlan]

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!

[SMAutoRepairLLC]

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.

[danieljohn]

Thank you so much for this video. I was having the multiple random misfires with my 19 blazer with the 3.6. Happened along 60k i threw the parts cannon at it too. Plugs, coils.. no change.. i ended up having some bad gas? I threw a bottle of heat in the tank and it helped. But having this issue led me to this video. So i will definitely keep my eyes on the timing!

[SmittySmithsonite]

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. :)

[MarzNet]

Excellent video. You can see a small effect of timing being off a bit on the relative compression test.

[Coodeville]

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.

[tonyq]

Very any of you Saab guys out there, I am currently dealing with this same issue on the 2.8 which is the turbo variant of this motor. The timing procedure is the same. My car eventually sets a misfire for bank 1, 3, 5. I’ve done it all, coils, injectors, spark plugs, vacuum, smoke, compression. The misfire sticks to that one back, a CEL can come on in a couple days or even weeks after clearing it. There are very few of us out there but this is indeed relevant.

[nelsonnarciso]

Well done brother. Win for the scope again.

[nicknicu]

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 👍!

[mrkttrdr]

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!

[jeremyanthonywr]

Welcome back Mike. Excellent video as always.

[bartscave]

Great diagnosis! Thanks Justin for sharing your known good waveform.