Dealer not honoring warranty work..2018 5.3 Yukon issues

[Bob2C]

This is what I am seeing on another 7 min ride, looks like Bank 2 is not doing well Cyl #7 is consistently showing misfires

View attachment 234291

I had a few misfires on 3,5,7. 7 being the most but not as much as you. I pulled a full report. Trying to figure out how to get it to you. It’s an html file.






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[Doubeleive]

I would check for a intake leak, nobody will probably agree with me but I have seen it before, you can do it with a can of starting fluid along the edges of the intake and see if the idle changes won't cost you anything but a couple dollars for a can of starting fluid. Better to do it first thing in the morning while everything is cold.

 

[smokey_mountain]

I would do that. My problem is that I cannot prove anything to the dealer to fix it. Misfires are recorded in OBD monitors on the same bank of cylinders that independent engine mechanic measured injectors being out of spec. There are still no trouble codes anywhere in the system on that. I suspect 11-15 misfires is not enough to trigger any DTCs. The fallacy of this situation that GM and dealer won't admit that there is a rough idle problem until there is code recorded even then there is no guarantee that they would accept it. At this point I am not sure what I need to do, if I show this misfires to the dealer, they will say "within spec", "incorrectly measured", "consumer OBD scanners are not acceptable", "you (me in this case) are an idiot and do not know how to interpret misfires", "no codes - no problem", etc.

I would check for a intake leak, nobody will probably agree with me but I have seen it before, you can do it with a can of starting fluid along the edges of the intake and see if the idle changes won't cost you anything but a couple dollars for a can of starting fluid. Better to do it first thing in the morning while everything is cold.

 

[calif phil]

You could induce a vacuum leak or pull off a couple of plug wires to log a DTC. Then maybe they would take a better look.

 

[91RS]

Cylinder 7 is bank 1 not bank 2.

 

[smokey_mountain]

I stay corrected then. Misfires on the odd cylinders but out of spec measured even cylinders. Now, there is no logic in my finding at all then - bottomline: truck is still rough idling and now even in P both cold and warm.

Cylinder 7 is bank 1 not bank 2.

 

[Doubeleive]

I would do that. My problem is that I cannot prove anything to the dealer to fix it. Misfires are recorded in OBD monitors on the same bank of cylinders that independent engine mechanic measured injectors being out of spec. There are still no trouble codes anywhere in the system on that. I suspect 11-15 misfires is not enough to trigger any DTCs. The fallacy of this situation that GM and dealer won't admit that there is a rough idle problem until there is code recorded even then there is no guarantee that they would accept it. At this point I am not sure what I need to do, if I show this misfires to the dealer, they will say "within spec", "incorrectly measured", "consumer OBD scanners are not acceptable", "you (me in this case) are an idiot and do not know how to interpret misfires", "no codes - no problem", etc.

i figured the point was to find the problem, regardless of who pays for it to be fixed in the long run. just offering a suggestion of what the problem could be.

 

[swathdiver]

Right, maybe it's the other bank with the problem since that is where the misfires are. Look, I have the older generation engine so it's not the same as yours. I have NEVER recorded a misfire on any cylinder with my Tech-2 running for hours at a time while we drive around. That being said, I would imagine that the engineers have a number that is not acceptable somewhere you have to find it. I'm still having trouble with my eyes but will look through my shop manuals for the GEN IV engines and report back if I can find where the information resides.

This is all good though, you know have another piece to the puzzle.

 

[swathdiver]

Ok, not finding a specific threshold before codes are thrown. However, the manuals do describe your exact conditions and suggest checking the fuel for contamination and the plugs and wires. If this were my truck, I'd run only Top-Tier high octane gasoline in it, then put dielectric grease on all spark plug ends which also makes sure they are all properly seated. I would also verify the gap on the spark plugs. Another thing mentioned in the book, was to make sure the injector harness was plugged into the right cylinders (no brainer right?) and misfires on 1 and 7 (2 and 6) could be an impending sign of an AFM problem coming up. Hope this helps Dmitry.

 

[smokey_mountain]

Thank you, I spoke to RPM Motorsports briefly just now, and their answer is that it does not sound right, 11 misfires in <7 minutes, does not sound right. Of course phone diagnostics is not effective they only go by what I describe and what I see on OBD. What puzzles them as well how the threshold is set that I do not get DTCs.

Right, maybe it's the other bank with the problem since that is where the misfires are. Look, I have the older generation engine so it's not the same as yours. I have NEVER recorded a misfire on any cylinder with my Tech-2 running for hours at a time while we drive around. That being said, I would imagine that the engineers have a number that is not acceptable somewhere you have to find it. I'm still having trouble with my eyes but will look through my shop manuals for the GEN IV engines and report back if I can find where the information resides.

This is all good though, you know have another piece to the puzzle.