Fuel trims
I can watch fuel trims while I drive with my PLX OBDII Multi Gauge.
Just seeing if I can get a concencus on what is normal. In cool weather my LTFTs are around +5 to +8 at idle and light load. There seems to be two load ranges before going to open loop. After the calculated air flow exceeds 6.0 the LTFTs go to about +1 to +3/+ 4.
HOWEVER, during this heat wave I've been watching my LTFT climb to +17 to +20 at idle and low load and +5 to +8 before switching to open loop.
My IATs are around 125+F, it's 100F outside latley.
From my motorcycle jetting days you would lean a motor out for higher temps/altitude.
For ice racing you would fatten your jetting up to keep the motor from leaning out due to the cold dense air.
Why does it seem that the ECU is enrichening at higher temps?
I have seen RUMORS on the interwebs that Mercedes Fuel Trims are displayed backwards. ie +20 would be PULLING fuel not adding. This would make some sense in that it's pulling fuel for the hotter IATs.
If I had an adjustable fuel regulator I could just crank the pressure and see which way the trims go, but that is on the mod list of dreams for now.
WHATDOYATHINK????