05-12-08, 10:21 AM
From what I understand, the Northstar engine undergoes some sort of re-learning process after the battery has been disconnected for awhile. I think I have experienced this the few times---seems like I have greatly reduced fuel economy for the first two or three tanks of gas after the battery has been replaced and the codes reset. What all exactly gets relearned during this time? I thought many/most of the "lessons" learned were stored in the EEPROM and didn't get erased when the battery is removed?
a few things get in the relearn but you are seeing the effect of LTFT Long Term Fuel Trim
Don't take this as gospel but I believe what gets re-learned is more based on the PCM (power control module) and the effected areas have to do mostly with transmission shift points, not engine control.
05-12-08, 12:24 PM
is no eprom on an OBD-II car
05-13-08, 01:05 PM
so the prom codes are all perma static?
05-13-08, 02:17 PM
The PCM doesn't lose a thing. Some body modules and personalized seat settings might hiccup, and idle characteristics might change for a while, but the basic PCM is unaffected.