Originally Posted by tunaglove
With cooler weather my fuel trims have returned to a more reasonable level. I consistantly get LTFTs of around +5 to +8. We had a 102F day and my IATs would sit at 135. Fuel trims then where aproaching +20! I also notice that these trims are somewhat carried over to open loop as my AFRs are dipping down to 10.8 at around 4K. I'm pretty sure if I dissconnected my battery and reset my LTFTs to zero that my open loop AFRs would lean out to the 12.5 I want and had for a while.
I ordered an AFPR, plan on increasing pressure to get trims closer to zero then re-tune with EC.
You are discovering many of the same issues that were going on in the early days of turbo buick tuning. Any learned adaptives were being transferred into open-loop fueling. Dialing up fuel pressure would enrichen AFR's for a short time, but would soon return to nominal after re-learning. It wasn't until we had the capability to tune/program the ECM that a permanent solution was found.
Looks like you may have verified that positive (+) trims add fuel.