I am trying to help my neighbor out with their vehicle and while driving it I noticed there is something up with the fuel trims. Stock vehicle, stock tune. 2007 Yukon 5.3.
Attached is the log, 2:02 and 2:26 are where it acted up. 2:26 was letting off the gas. Also threw a P0171 at this time. (Lean Bank 1), looking at the log, am I looking at a sensor issue or an actual lean condition. I am still learning.
I don't know if its related, or normal for these gen 4's but it also seems to have a lot of KR at cruise. Any help is much appreciated, still learning! Thanks!
your getting a fair amount of knock in that tune however when the lean spot happens the o2 pegs low voltage id suggest changing that o2 on that bank and re check or swap them and see if the lean condition moves banks. a vac leak would cause a lean on both banks
I swapped the O2 sensors and I have the same results. Same scenario, when the pedal is lifted and coasting tends to aggrevate it.
Here is the log file, starts to go wonky around 9:15 (Sorry for the long log, warming up idling).
Anyone have any thoughts?
Edit: Neighbor said they had some work done recently, had the oil pressure sender replaced. Looked at the invoice, noted a few prior codes but not P0171, $109.98 for new intake manifold gaskets during that job. Wonder if they screwed something up...
Last edited by SixSpeed; 05-04-2019 at 07:09 PM.
Reason: Forgot File
i was going to say intake gaskets would of been my next point to check or for exhaust leaks by the o2 sensor. new style gaskets are green. i guess it could be a bank specific vac leak if it was only 1 side of the intake gasket. smoke the induction system and see if you find any leaks
also that knock is getting high. what fuel you are you running. if its 87 you can do a test and put some 93 in and see if that knock goes away and if not then id assume it to be false
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