I'm trying to figure out my sis-in-law's '03 2.2L GMC it first gave a code for misfire on #4 cylinder and I cleared it and then about a month later it came back and the truck was running rough. So someone changed out the fuel filter and #4 spark plug (yeah I know 1 instead of all 4 plugs) and it's still doing the same thing. So I pulled the #3 and it looks like it's burning oil so I was going to change all the spark plugs and wires. But before I do that I decided to scan it for more codes and came up with "Fuel Injection circuit malfunction" for almost all cylinders and the misfire code on cylinder #4 is still there. What should I check for on the fuel injection circuit malfunction code? Thanks.

 

Can be internal PCM problem, injector connector(s), intjector stopped up, or a short circuit in the harnes somewhere.

 

Well I think it's all four injectors cause I remember 5 codes now that I think about it...I'll try looking for a harness connector that got knocked loosed or something. I hate working behind someone just for that reason...Thanks for the reply...

Zed