2005 Avalanche

[Biguy Matt]

Working on 05 avalanche that starts and runs fine...seems like when it goed closed loop, it overfuels with much black smoke and flashing engine light. A friend changed mass air flow, intake and gaskets. Still runs rough.

[Wires]

Working on 05 avalanche that starts and runs fine...seems like when it goed closed loop, it overfuels with much black smoke and flashing engine light. A friend changed mass air flow, intake and gaskets. Still runs rough.

 

What codes is it throwing? There is a boat load of crap on an EFI that can cause fueling issues. Grabbing the codes out of the ECM should point you to what is wrong.

[jro909]

probably oxygen sensors...flashing engine light i think means misfire or detonation if i remeber right

[hockeypro1411]

The flashing CEL is probably a P0300 code (random/multiple cylinder misfire). I'd put my money on O2 sensors or MAF.