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Question I have an 85 Chevy Astrovan with the V-6 TBI engine (150k miles). Under load, the engine sounds like it's knocking badly. It's gotten worse in the last few months. I thought that it might be a bad vacuum advance unit, but the Haynes manual states that there is not vac. advance. What other components do I need to look at? Note that the timing is set to spec and the problems don't go away with premium gas. Thanks very much, Greg

Reply ...[we were unable to e-mail you our reply] Thanks for writing, Greg. I'm going to assume that you're describing a spark knock and ping. I would recommend testing EGR function, EST (Electronic Spark Timing control) operation, and inspect for the possibility of excess carbon buildup. (Note, EST Astrovans utilize a knock sensor to retard ignition timing during detonation periods.) Good luck. Angelo Silverado Auto Service