PCM learns then forgets with I turn it off
PCM learns then forgets with I turn it off I have a 98 Z28 and say I change the IFR table with Edit. After I flash the PCM I crank the car I monitor STFT, LTFT, FTC and a few other items. The car is in FTC 20 until it transitions to FTC 17. While in FTC 17 or any other FTC the STFT goes negative or positive and the LTFT follows until the STFT is 0 which is how it is suppose to work. As the car transitions between FTC the PCM applies what it has learned and sets the fueling at the last known point that had a STFT of 0 for the existing operating conditions. All this works fine on my car until I turn it off.
After I turn the car off for any length of time and restart it the PCM goes to FTC 20 with LTFT locked at -1.6% and after about 2 – 4 min it transitions to FTC 17 with the LTFT at -1.6% and the STFT goes to some negative number until the LTFT goes to -5.5% or what ever value is settled at before I turned the car off.
I have checked all the PCM connections for corrosion, dirt, and connection. All the fuses are fine and all the grounds are clean and tight.
What conditions need to be met for the PCM to learn and remember?
Any ideas on what the problem is?
Thanks
John
After I turn the car off for any length of time and restart it the PCM goes to FTC 20 with LTFT locked at -1.6% and after about 2 – 4 min it transitions to FTC 17 with the LTFT at -1.6% and the STFT goes to some negative number until the LTFT goes to -5.5% or what ever value is settled at before I turned the car off.
I have checked all the PCM connections for corrosion, dirt, and connection. All the fuses are fine and all the grounds are clean and tight.
What conditions need to be met for the PCM to learn and remember?
Any ideas on what the problem is?
Thanks
John
Re: PCM learns then forgets with I turn it off So after the PCM goes to FTC 17 after I restart the car shouldn’t the LTFT go back to -5.5%, which is the last known and “learned” LTFT value that produced a STFT of 0?
John
John
