4.2L LL8 Engine Noise and Vibration 800 - 900 RPMs - 4.2 console GMT360 motor pedal rattle speed steering temperature vehicle wheel

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

Engine buzz noise, and vibration felt at the accelerator pedal, steering wheel, and center console at 800 to 900 RPMs.

Verify the intake pre-plenum is securely mounted. Press down on the intake plenum near the PCM and if the vibration is eliminated, replace the intake pre-plenum with P/N 15176239. The pre-plenum is the plastic component on the top of the engine that has the 4200 Vortec logo embossed on it.

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.