[Wayne2]

Originally posted by DV93
I posted earlier; 02 Burb, 32k. Has knock during accleration for quite some time. did not knock when new (Feb 2002). So from what I am reading,it is #1) CARBON BUILD UP. #2) POOR QUALITY CONTROL/POOR ENGINEERING BY GM. But I thought the knocking was due to unburnt fuel igniting after it leaves the cylinder. That is why it happens during acceleration. Can anyone carify?

The "knocking" you refer to can be caused by a few different things but NOT by fuel burning after it leaves the cylinder. That type of knocking is caused by the fuel being burned before it should. Providing the ignition timing is correct, the charge is burning before the spark sets it off. Things such as low octane fuel, & carbon deposits in the cylinder still red hot will result in an engine knock or "ping". Then we have the "rod knocking" sound that originates from a bad O-ring in the oil pump. BUT most are complaining from the sound of the engine that is a clattering due to poor piston to cylinder wall clearance.

Pinging - Why are these engines building up carbon more than any other engine?
Knocking (oil pump related) - TSB out on this. If it is loud enough GM will warranty.
Clattering - Poor engineering. GM has attempted to fix some. Some got worse. Lawsuits are gaining momentum on this.

Question: Did they do something to the '03 engines to stop this? I don't see complaints from '03 owners .... or did I just miss something?