Originally Posted by
The_Ghost
I just figured out what was wrong with mine. I was seeing major erratic behavior with STFT. At idle I would see -30.47 and stay there after a WOT. Then the next 5 minutes it was normal. My AFR would be 10.7 and then go normal to 14.7. Try cleaning the connector and plug on your HPFP. I have been getting the CEL of p2188 "too rich at idle" for 8 months and been chasing it!!! Cleaned the connections and it is now fixed!!! I just spoke to a GM engineer that specializes in driveability issues and fixes for the LNF line....