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I have a detonation or knock problem i'm trying to solve during acceleration

(2001 Saturn SC2)
in San Diego, CA on May 11, 2014
There are no codes stored in the pcm. Ive replaced both 02 sensors, fuel filter, anti knock sensor, spark plugs/wires, and the pcv. Ive disassembled and cleaned the throttle body, run a heavy duty 3m injector cleaner through her, checked for vacuum leaks,
checked the egr isn't clogged, removed and flushed all the valve lifter, fuel pressure is 48 lbs steady, and still.

It is a wrapping that is most pronounced aroundf 3000 rpm when you are just about to shift. It vanishes if you let off or nail the throttle to the floor So its maintaining a rpm + or - 10% throttle otherwise it disappears.

Im thinking it could be mechanical at this point but not typical symptoms in my exp. Im ready to tear her down but wonder its something I may have missed with the pcm or sensors controlling it to do so...
Displaying 2 answers & 1 comments
Popular Answer
on May 12, 2014
could be a timing issue but I would run a tank of high octane fuel through it first
on May 12, 2014
Ok, did that with octane boost first thing. However, lets say that made it stop, Id still wanna know the underlying issue since the car has run 90,0000 on regular without an issue. Its not like compression increases as a motor wears, maybe a carbon deposit but it wouldnt have survived the can of seafoam I ran thru the fuel system and down the throttle body... Any other ideas or something I missed?
of Swedish Auto Tech on January 26, 2017
Octane booster will not help you in this case, just fill up with 91 octane and test it again
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