Trippah wrote on 08/30/09 at 21:12:38:Boule'tard..I never understood why people suggest running a premium gas..if by premium you mean higher octane. Unless MMRanch has modified the compression, regular swill is more than sufficient.
It is, and I've never gotten any noise running 87 octane gas. But I can't help but think the higher octane reduces spark-knock under high load/low RPMs even at the stock compression ratio.
Quote:He could drain the tank and add fresh gas but if the sound has been for the past several thousand miles, that's at least ten tankfuls so unless it's all from the same fuel storage tank, it can't be a culprit.
It's possible he's got excessive carbon buildup (which aggravates knocking) that has just become evident in the last couple thousand miles. The other advantage to premium gas is that they typically mix in a higher concentration of detergents, additives, "Techron" or whatever, that clean out the deposits. A good dose of SeaFoam might also help.
Quote:By throttle related I suspect he is saying the sound becomes more frequent as RPM's increase, or gets louder.
That could be the case. I was thinking the sound only occurs when he whacks the throttle open at too low an RPM, which would tend to induce spark-knock or piston slap. But yeah, if the noise increases with RPM (all other things being equal) it's time to bust out the tools.