Spark knock?

[Infinitrium]

Today I went to take out my air filter to see how dirty it really was, and the rubber seal just tore away when I pulled it out, so for now I'm running without one. One thing I've noticed that I didn't when I had the air filter in the car, for some reason, is a sharp metallic snapping sound, something like spark knock. As far as I can tell, it only happens from idle up to about 3000 rpm then it goes away. It only seems to happen with heavy throttle, such as going up a hill, or even pressing the gas to the floor in neutral. Could this be that my timing is still off, or could this be something else?

[gomer]

Chances are that it is spark knock ,, at higher rpm the piston is outrunning the shock-wave from the uncontrolled combustion and/or at higher rpm there is enough of a reduction in load that you have normal combustion... sometimes the smallest things can unmask problems... this issue may have been happening previously or perhaps losing the gasket is now allowing hot engine compartment air to raise your charge temp just enough to put you into a pinging state...

[darkdan]

I bet you just haven't heard it before. Chances are it's carbon build up on the piston raising your compression. When I first bought my aspire and took the head off the piston tops were CAKED with carbon.

Try a piston soak with a decent solvent, a seafoam treatment or two done through the PCV hose, or use FP60 by www.lubecontrol.com

Be wary of most of the OTC fuel injector cleaners, most of them are just a $4 for a 12 oz bottle of kerosene.

[Infinitrium]

Are there any good OTC products to use for a piston soak? I've heard some Saturn owners use MMO and for them it seems to work. I did spray some carb cleaner through the PCV valve when I changed it. I don't know if it fdid any good or not.