Well aware this could turn into a big can of worms on the internet, but genuinely looking for useful input here, or maybe some PIDs I can start checking on the COBB AP to help diagnose before I start getting into more mechanical issues. Anyone else in CA experiencing this on their 91 octane tunes?
ECU Pulling Timing / OAR Changes Under WOT | Looking for Input
Issue:
ECU Pulling Timing / OAR Changes Under WOT | Looking for Input
Issue:
- ECU pulling timing and adjusting OAR during WOT pulls on both 91 oct and E30 tunes
- OAR sits between -0.78 and -0.84 on 91 oct tune during WOT
- Issue only occurs under high load — smooth at idle and normal driving
- CA 91 octane should be ~E10, recent sample tested at E5–E6
- Adding a gallon of E85 to either the 91 or E30 tune resolves the knock and OAR changes
- Tested two different 76 stations — issue persists at both, worse at the second
- Timing belt replaced - everything was dead on with double checking the timing locks and rotating the engine severals times back to TDC.
- AWR 70A durometer passenger engine mount installed... I might swap back to the stock mount just to rule this out.. but does NVM result in OAR changes?
- Spark plugs — no fouling, gap correct
- Charge temps — 5–6°F above ambient during WOT pulls
- IAT — stable during pulls, not spiking
- Knock appears mostly even across all cylinders during WOT
