Chasing my tail over trims and wandering AFCMD!
Posted: Mon Nov 14, 2022 5:09 pm
First post on the forum and trying to understand some logic as to what is going on with my calibration.
Setup is a 08 AP2 with a custom built turbo kit with ID1050x injectors, walbro 485 pump, ktuner flex content conditioner for flex fuel.
This is my personal car and daily driver so getting it perfect is always a nagging game...however I've run across something that I cant figure out despite checking the calibration and reading all of the available help.
Primary issue at hand is the fuel trims get wound down into the negatives which is problematic since the ecu applies that long term global trim to all the fueling including the wide open/boost fueling.
I've tried to track down and isolate it to as why the trims wind up as the car was tuned to stoic at all areas outside of WOT enrichment.
From what I've found so far the AFCMD target seems to be floating and the trims try to chase it but as it ends up being different than stoic it causes the trims to pull fuel even though the logged AF is correct.
For example: closed loop stoic target is set to 1, but while at idle and driving the ecu will flick the AFCMD anywhere from 1-0.92 while the engine is running and because the AF is significantly leaner than the value it randomly chooses it will wind up the trims to take fuel out (even though you would expect it to add...).
This causes a fairly large negative correction which takes absolutely forever to trim back as the ecu is quick to pull fuel but wont add it back in (even with short term trims winding up to their max values).
Very frustrating to say the least especially now that I am trying to sort out flex fuel.
Also it would be nice to be able to adjust injection timing on this ecu to optimize the larger injectors as well as a WOT lambda trim table for ethanol as they always run significantly richer wide open on ethanol which is really the wrong way to go with that fuel.
Any thoughts are appreciated!
Its also worth noting that my knock control value never changes from 55% so I have had to dull up the knock tables and tune the ignition tables to keep the timing in the engine as well as negate knock, again frustrating coming from the standalone world.
Setup is a 08 AP2 with a custom built turbo kit with ID1050x injectors, walbro 485 pump, ktuner flex content conditioner for flex fuel.
This is my personal car and daily driver so getting it perfect is always a nagging game...however I've run across something that I cant figure out despite checking the calibration and reading all of the available help.
Primary issue at hand is the fuel trims get wound down into the negatives which is problematic since the ecu applies that long term global trim to all the fueling including the wide open/boost fueling.
I've tried to track down and isolate it to as why the trims wind up as the car was tuned to stoic at all areas outside of WOT enrichment.
From what I've found so far the AFCMD target seems to be floating and the trims try to chase it but as it ends up being different than stoic it causes the trims to pull fuel even though the logged AF is correct.
For example: closed loop stoic target is set to 1, but while at idle and driving the ecu will flick the AFCMD anywhere from 1-0.92 while the engine is running and because the AF is significantly leaner than the value it randomly chooses it will wind up the trims to take fuel out (even though you would expect it to add...).
This causes a fairly large negative correction which takes absolutely forever to trim back as the ecu is quick to pull fuel but wont add it back in (even with short term trims winding up to their max values).
Very frustrating to say the least especially now that I am trying to sort out flex fuel.
Also it would be nice to be able to adjust injection timing on this ecu to optimize the larger injectors as well as a WOT lambda trim table for ethanol as they always run significantly richer wide open on ethanol which is really the wrong way to go with that fuel.
Any thoughts are appreciated!
Its also worth noting that my knock control value never changes from 55% so I have had to dull up the knock tables and tune the ignition tables to keep the timing in the engine as well as negate knock, again frustrating coming from the standalone world.