Thread: Car running LEAN right after it was running fine for what reason?

Originally Posted by bandook

"I just loaded my last adjustment and drove for about an hour to get another scan. over the last couple weeks of tuning I've noticed if I make adjustments from scans taken too soon after an adjustment it leans the fueling. I went on grand prix forums this morning and discussed the lean situation and they suggested I unplug my evap and then turn the evap code off. I did so when I loaded this last adjustment. looking at my maf ltft's after this scan was done and they are damn near perfect in every cell recorded. think I have an evap problem?"
~SgtMarshal

Found this in an old thread. I even commented in the thread, lol. Think I'll just delete the evap. Pretty sure I have one or two of the codes disabled already as I've always had a cel for evap I couldn't fix. Between evap and super high IAT's I think we've narrowed down the tuning irregularities.

Also I should be getting the proper values for my sd 60's soon. Finally will have a clean base for a good tune. 

i had to highlight that post to read it. I remember my evap causing issues when I was tuning the car. deleted the evap and all my irregularities went away. i also deleted the egr because it was doing funny things too. There are something like 10 codes for the evap all in the P0440 range.

on a different note, a year or so ago I installed a ported lim that I modified so I could install an air temperature sensor that read through the iat, and i remember it definitely affected my fuel trims. I don't remember if it read lean or rich, but I remember they were wonky until I unplugged that sensor and plugged it back into the regular iat sensor.