Chevrolet Repair: Valve clatter, vacuum hoses, chevy tahoe

Question
1998 Chevy Tahoe LT, 130K miles. Upon acceleration, I hear the vales chatter? Are they self-adjusting? IS IT the vales? Hogher octane helps, but I'm confused.
Thanks for your time!


Answer
Hi Greg,
That isn't the valves. It is pre-ignition ping, also known as spark knock.

The knock sensor is supposed to detect that, and retard the timing to eliminate it.

Carbon buildup may be the cause, as well as a possible vacuum leak.
Clean the EGR valve, check the vacuum hoses, and consider using some Sea Foam. Do a Google search for Sea Foam.

Van