To keep things EXTREMELY simple, I've broken down the long term
fuel trims to these sliders.
1G's
LTFT Lo = 50Hz Airflow Slider
LTFT Mid = 150Hz Airflow Slider
LTFT Hi = 250-400 Hz Airflow Slider
2G's
LTFT Lo = 50Hz Airflow Slider
LTFT Mid = 150-400Hz Airflow Slider
Adjusting fuel trims with the above information makes Rev MAFT calibration
very easy. Obviously we still need MAFraw captured along with STFT and all the LTFT's. Also make sure you are at your thermostat's
operating temperature.
Step 1) Rev to 50Hz
Step 2) LTFT lo + STFT = Your 50Hz adjustment
Example : If STFT is +7% and LTFT Lo is +3%, then adjust your 50Hz
airflow slider 10% higher than it currently is now.
Step 3) Rev to 150Hz
Step 4) LTFT mid + STFT = Your 150Hz adjustment
Example : If STFT is -11% and LTFT Mid is +4%, then adjust your
150Hz airflow slider 7% lower than it currently is now. And continue to repeat for LTFT Hi for 1G's.
Step 5) Cruise on the road until you can get a stable 250Hz
Step 6) Repeat equation until lower airflow sliders are calibrated
I also want to mention what the DSMlink manual suggests when LTFT
Lo and LTFT mid are far apart from each other. If LTFT Lo is positive and LTFT mid is negative, then increase dead time. Vice
Versa. This is another tool you can use when fine tuning LTFT's.
NOTE : You must be patient when calibrating the
lower airflow sliders. The ECU will take it's time readjusting the LTFT's. The best thing to do is to calibrate the GMAF using
the steps above and then just recheck them after a day of driving. Adjust again if neccesary.
Good Luck.
