Cross Injector Wires Causing Misfire - 3.1 3.4 DTC driveability idle LA1 LG8 MIL P0300 P0301 P0302 P0303 P0304 P0305 P0306 performance rough run

When servicing the vehicle with the VIN you entered, the following diagnosis might be helpful if the vehicle exhibits the described symptoms.

Misfire at steady state speed and RPM, MIL illuminated, and a P0300 set

If the fuel injector harness has been off, there is now a misfire at steady state speed and RPM and normal diagnostics have failed to identify the cause, suspect crossed fuel injector connectors. Remove the manifold and check the color code of each circuit to verify its routed to the correct injector.

Important: The rear cylinder head is the odd bank (1-3-5), and the front head the even (2-4-6). The numbers cast into the intake make it look the opposite because the runners cross to the other side.

.

Please follow this diagnosis process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed. If these steps do not resolve the condition, please contact GM TAC for further diagnostic assistance. This diagnostic approach was developed for the vehicle with the VIN you entered and should not be automatically be used for other vehicles with similar symptoms.

(00 - 04 Buick Century) and (00 - 04 Buick Rendezvous) and (00 - 04 Chevrolet Malibu) and (00 - 04 Chevrolet Impala) and (00 - 04 Chevrolet Monte Carlo) and (00 - 04 Chevrolet Venture) and (00 - 04 Oldsmobile Alero) and (00 - 04 Oldsmobile Silhouette) and (00 - 04 Pontiac Aztek) and (00 - 04 Pontiac Grand Am) and (00 - 04 Pontiac Grand Prix) and (00 - 04 Pontiac Montana)

.