My buddy swapped an 04 LQ4 into his 00 Sierra about three weeks ago. The last few days, it has began to misfire. We assumed its either an injector, coil pack, spark plug or wire because its only two cylinders misfiring. after swapping coils, plugs, wires, and the injectors, the truck still continues to misfire. note that the misfire is only on cylinder 1 and 5. he had the truck hooked up to a machine and none of the other cylinders were misfiring. the number 1 cylinder fluctuated from 5 misfires to 16 misfires. what would you suggest he do next? is it a possibility that its a tuning problem since he's replaced the 'mechanical' parts? thanks in advance!

 

"xlcooplx" what is your email address? I want to ask you a couple questions about your truck.

 

why not just PM me?


anyone have any ideas?

 

You still havent sorted that miss out yet?

 

unfortunately no. like i said, we've replaced plugs, wires, coil packs, and injectors on the two cylinders that are misfiring and its still doing it. and for the record, he has had the truck tuned for the LQ4. we're not sure where to go from now... i wish we had a pcm with a stock 6.0 tune to see if we could rule out the tuning issue of it or not.

 

Do you have access to a noid light set? Did you check and see if an injector wire got pulled loose from the terminal? Noid light would be an easier way though. Reason im stressing this is I had this same problem. It was one little injector wire loose on a single injector giving me all that trouble.

 

Noid light? Also, the injector is working. At first, the plug in the 1st cylinder was wet. After replacing the old plug with a new one, that problem ceased, yet it still misfires.