Dealer not honoring warranty work..2018 5.3 Yukon issues

[BG1988]

I was reading the bulletin.

https://static.nhtsa.gov/odi/tsbs/2019/MC-10163272-9999.pdf

There doesn't seem to be anything that voids the warranty by just using a reader. But, I don't think I would disclose to the dealer/GM that I was using any other device.

What is seen in the bulletin is people were dumb enough to take their vehicles into the dealer and leave stuff plugged into the OBD. I don't think GM has programmed the ECUs to track when a device access the port.

i'm pretty sure that would be pretty hard to prove that it caused damage it might even be illegal

 

[91RS]

High resistance in a battery cable is not going to cause a fire...

It’s ridiculously easy to prove a device plugged into the OBD is causing problems when it’s unplugged and the problems go away...

 

[smokey_mountain]

The truck is with the dealer, they are doing mounts TSB, I am paying for this TSB to be performed, dealer promised to do this TSB to a T and reseat both engine and transmission. My decision was to run to the end of the rainbow as I hate to take a loss on it. My fingers crossed...

 

[cesarqjr]

Looking forward to the results. My 2019 LT with 48k miles is exhibiting the same symptoms.


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[smokey_mountain]

I owe this forum my update... after 4 days in repairs my truck is back with brand new mounts all around and ... $1100 down the drain. No improvements. Same rough idle, but, of course, all within the GM spec.
I wanted to thank everyone on this forum for camaraderie and support. I ran to the end of the rainbow and there are no unicorns there.

Bottom line:
1) new plugs or wires did not change a thing
2) mounts did not cure anything

Original troubleshooting done by an independent GM tech was pointing to a faulty injectors but given no codes, I do not think I can do anything about injectors. Time for my plan B.

 

[dnt1010]

You cannot give up, you must persevere and find the actual problem for the sake of the forum. Please proceed with having the injectors replaced. it is only money...................... (I love spending OPM)

 

[smokey_mountain]

True only money, that is why Koreans got them this afternoon. Wish I could spring for a Japanese again but GM got most of my budget at this point Toyota is out of my reach.

You cannot give up, you must persevere and find the actual problem for the sake of the forum. Please proceed with having the injectors replaced. it is only money...................... (I love spending OPM)

 

[HiHoeSilver]

True only money, that is why Koreans got them this afternoon. Wish I could spring for a Japanese again but GM got most of my budget at this point Toyota is out of my reach.

Appreciate the follow up and closure. Gotta say it, though...I can't believe that after all that, you didn't just tune that thing!!!

 

[smokey_mountain]

I bought BB kit was ready to tune but it occurred to me if out of 9 similar 5.3 trucks I drove 7.5 exhibit perfect idle even at 490-500 RPM, tuning will just mask the problem when this truck runs correctly it runs well even at designed 500rpms when truck misfires it will misfire even at 600 RPM I revved the engine to 600 and still felt the misfires. My misfires are very obvious and not subtle, everyone who sits in the truck feels them right away, no doubt about it. This is not a low idle situation, this is a clear misfire somewhere in fuel or maybe in the ignition coils. Who knows at this point...

Appreciate the follow up and closure. Gotta say it, though...I can't believe that after all that, you didn't just tune that thing!!!

 

[SnowDrifter]

Long ass thread, not going to read 25 pages. So sorry if I'm repeating anything

I'm wondering if it's cycling back and forth between lean and rich, and misfiring on lean. And you might have an injector that's underperforming to the point of misfire. Either rich or lean. Not sure what the GM spec on it is on the new rigs but I seem to recall reading somewhere a while ago that the tolerance for flow on older rigs that +/- 15%. I'm unable to locate that at current to take that with a grain of salt.

Sooo, my thought is this: See if you can find a good scanner. Figure out which cylinder is misfiring, if it's even tripping the misfire monitor. Cross reference that with the commanded fuel flow and/or oxygen sensor voltages.

If possible, see if you can tune or otherwise command the rig to run a bit rich to see if that alleviates the issue.


You might also try investigating your spark plug gaps. Narrow them down a few thousandths. See if there's some weird intermittent weak spark

 

[smokey_mountain]

Thank you. 15% is the tolerance on injectors during the test per GM spec.

Long ass thread, not going to read 25 pages. So sorry if I'm repeating anything

I'm wondering if it's cycling back and forth between lean and rich, and misfiring on lean. And you might have an injector that's underperforming to the point of misfire. Either rich or lean. Not sure what the GM spec on it is on the new rigs but I seem to recall reading somewhere a while ago that the tolerance for flow on older rigs that +/- 15%. I'm unable to locate that at current to take that with a grain of salt.

Sooo, my thought is this: See if you can find a good scanner. Figure out which cylinder is misfiring, if it's even tripping the misfire monitor. Cross reference that with the commanded fuel flow and/or oxygen sensor voltages.

If possible, see if you can tune or otherwise command the rig to run a bit rich to see if that alleviates the issue.


You might also try investigating your spark plug gaps. Narrow them down a few thousandths. See if there's some weird intermittent weak spark

 

[SnowDrifter]

Thank you. 15% is the tolerance on injectors during the test per GM spec.

Nice

So, then next step is to determine which cylinder(s) have a misfire and swap injectors around. You can get some weird shit happening where a lame injector will cause a neighboring cylinder to misfire. What I'd do is swap to a cylinder on adjacent bank as well as the neighboring ones

i.e.

If your engine layout is
1 2
3 4
5 6
7 8

And cylinder 4 is misfiring

You'd swap
1-2
3-4
5-6

Take note of what's what, keep track of it. See if it follows

If it does, then you can do a swap back on 3-4. If it follows, then you've found your issue. If not, then swap 1-2, test again, then 5-6

 

[smokey_mountain]

Swapping injectors on recent engines is crazy hard, requires some special tools, there is a post earlier that explains why, what used to be 20 mins affair is now multi hour if one has tools. It could be done but not by av average weekend warrior.

 

[SnowDrifter]

Swapping injectors on recent engines is crazy hard, requires some special tools, there is a post earlier that explains why, what used to be 20 mins affair is now multi hour if one has tools. It could be done but not by av average weekend warrior.

Oh hell are these direct injection?

You might go back to see if you can get it to run rich then. There's no real easy way around those

 

[Kpwweb]

So, crazy thought—what about the in-tank fuel pump? Have you tried a full-throttle acceleration when misfiring at idle? I had to replace my in-tank fuel pump due to slight stumble at idle and big stumble under WOT. Some of the in-tank pumps are questionable, especially when hot. Other thing to check is the fuel pump controller.

The in-tank pump feeds the direct injection pump (think lift pump). If it is borderline, it can lead to problems. Wot start off idle would show this.

 

[smokey_mountain]

Interesting thought... What would be the way to test for it? At this point, I have to try a thing or two but myself, I am done with dealers, they will not help as GM does not accept the problem.

So, crazy thought—what about the in-tank fuel pump? Have you tried a full-throttle acceleration when misfiring at idle? I had to replace my in-tank fuel pump due to slight stumble at idle and big stumble under WOT. Some of the in-tank pumps are questionable, especially when hot. Other thing to check is the fuel pump controller.

The in-tank pump feeds the direct injection pump (think lift pump). If it is borderline, it can lead to problems. Wot start off idle would show this.

 

[smokey_mountain]

I am not a litigious person but I feel really frustrated that GM is not willing to help, I spent now $1890 of my personal money trying to fix the truck that is only 11 months into bumper to bumper manufacturer's warranty. Are small courts effective or are they giant waste of time?

Desperate to get the truck running normal. Now that I drove enough of 2018-20 Tahoes and Yukons trucks, these trucks can run smooth.

 

[swathdiver]

Interesting thought... What would be the way to test for it? At this point, I have to try a thing or two but myself, I am done with dealers, they will not help as GM does not accept the problem.

Get your app to show fuel pressure and stomp on the gas to 75 mph on an on-ramp somewhere. If all is well, the pressure will not drop more than a pound at WOT. You guys have a fuel system that I am not familiar with though. Mine runs at 43.5 PSI all the time.

 

[smokey_mountain]

I will give it a whirl and see. I went down the slippery path of arbitration to prep for a court. I am reading in numerous posts that GM's self-appointed "specs" allow up to 3-4 quarts of oil to be added and consider normal... this is out of control.

 

[Bob2C]

Get your app to show fuel pressure and stomp on the gas to 75 mph on an on-ramp somewhere. If all is well, the pressure will not drop more than a pound at WOT. You guys have a fuel system that I am not familiar with though. Mine runs at 43.5 PSI all the time.

Mine too has a rough idle. 2018 5.3. The motor mounts were replaced in the fall. In the beginning it seemed to help but it’s back and seems to be getting worse. I’m wondering if it’s destroying the new mounts from the constant movement. I did the fuel pressure test. Got it up to 50 from a dead stop. It didn’t drop. The low reading around 31 was idling in drive stopped. It fluctuated to 45. Do you think this is a fuel delivery problem? I have no issues with acceleration or hesitation.

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