Originally Posted By: ARCOgraphite
Originally Posted By: gathermewool
Also, I mentioned above about my abnormally high (to me at least) LTFT. Both of these might have contributed to the high fuel.
The stage 1 tune has a safe ++ rich fuel trim due to the high boost pressure. It could be dialed back a bit by a tuner. Is the car running a stoich mixture at no boost cruise throttle?
I'm just learning about tuning - hoping to start self-tuning within a year or so when I feel comfortable enough - but it's my understanding that the ECM will draw from the primary fueling tables for that load/RPM/Air temp and MAF signal, then add or subtract fuel via STFT and LTFT based on O2 sensor feedback. Regardless, if my tune is set to run rich - which it does, but mostly in open loop under boost, not in closed loop - it should indicate -LTFT as the engine tries to take awake fuel to maintain stoich, right? +LTFT means the ECM is seeing a leaner condition than it expected and is adding fuel to compensate.
In closed loop, at low loads or while cruising, the engine is always trying to maintain stoich. The only time I see it dip below is at the onset of boost. The richest I see is 11.05:1 under high boost, WOT conditions, but even that ramps down from stoich only as boost ramps up.
I hope this helps. I've got a lot to learn and looking at it from multiple angle - logging and UOA - is interesting. Hopefully we'll be able to find some correlations, though one UOA/6 months doesn't have quite the resolution as logging multiple times /second! haha