4.6L LH2 RWD Northstar Engine with P0300 Misfire Codes- kw accessory belt camshaft code DTCECM generator noise pulley

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

2004 4.6L (LH2) RWD Northstar engine with P0300 misfire codes. The P0300 code will set under extremely light engine loads( such as slight downhill, or in park/ neutral at 1000 - 1200 rpm) and will be evident in all cylinders when viewing the Tech 2 misfire graph display. The Tech 2 misfire graph display will show the misfire starting in one cylinder and then will spread to the remaining 7 cylinders. This misfire is usually not felt in the vehicle. No other PCM DTC codes will be present.

Inspect the serpentine belt tensioners for a concern of clicking/ chattering/ jumping. As part of your diagnostics, remove both serpentine belts. Then with the Tech 2, monitor the engine misfires as well verify the absence of the prior noises. If running the engine with both serpentine belts removed eliminates the concern, replace both serpentine belts. The small changes in the belt/ crankshaft speed are detected as misfires.

.

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.

(2004 CADILLAC XLR 4.6L (LH2) ENGINE ) and (2004 CADILLAC SRX 4.6L (LH2) ENGINE)

.