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Swapped PCM leading to low LTFT and idk why!?

J

Jrjrman

New member
Okay so I have a 2008 Grand Prix which, for some reason, isn't compatible with HP Tuners. To get around this I sapped out my 2008 PCU with one from a 2006 but even since I did the scanner is reading really low fuel trims when I'm at or near idle and I don't know why. I can't figure out for the life of me what is different between the 2006 and 2008 that would cause this??? Please help!
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go to rock auto and search for a maf for your car and the donor pcm's car and see if the part # is different. if it is, thats the issue most likely.
 
you can take some fuel from the maf. just a little bit in the lower areas, 1000-3000 is idle range, 3-7000 is cruise, 7 to the top is wot.
 


Have you compared the two bins for fueling and airflow? GM changed some stuff from year to year and if you look..likely you can find it and copy the table in.
 
2008 was a year only computer/calibration as they started the switch to can-bus, that is why it was never supported. Not worth their time to make a editable file for 1 year.
 


So do you tune pcm looking to get mines done or order one from zzp got p0171 running lean stft is about 20.3 and ltft 16.3 Ik those aren't right no leaks changed fuel filter no luck
 
97gtp01gt99gt said:
So do you tune pcm looking to get mines done or order one from zzp got p0171 running lean stft is about 20.3 and ltft 16.3 Ik those aren't right no leaks changed fuel filter no luck
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with those lean trims, you probably have a vacuum leak. check again.
 


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