I have a 1990 fullsize chevy blazer TBI 350. Stock except K&N air filter, Flowmaster exaust and headers. I was driving one day and it randomly started knocking/pinging really bad. I had a local mechanic looking at it and the knock count is messed up. It goes up to around 40 on acceleration but doesnt return on decel. Then itll climb again. It went from 40-70-130 and up to 200. It does this and retards or advances the timing (i dont recall which) and makes itself start knocking. We've tried three new knock sensors, a different computer, and had the spark control module tested and it was ok. Anyone have any ideas because we're baffled?

 

Come on guys. Any ideas? Please and thanks.

 

Bump!

 

Clogged cat? When you hit KR it pulls timing.

 

Kr? and doesnt hav a cat

 

KR= Knock Retard... Are you sure that there are no flow problems? any smashed spark plugs?

 

Nope. Any other ideas??

 

Doesnt seem to knock untill it has warmed up a little.