Can a faulty lowband TPS create a condition where detonation can occur under heavy load? I would think if the TPS is bad, it may be difficult to set the low side idle, and the timing. I have a little bit of detonation issue with my rebuild. It only does it when you really mash the gas. I know my lowside tps is out of specs. To get it to idle I adjusted the Screw on the top of the intake and futzed with the CAS to get it to set right.

 

how do you know it's detonating? Can you see it in the plugs? I'll be honest man, I advanced the crap out of my timing back in the day (rotated the CAS) on straight 87 octane, made 172rwhp (s4 car), and never detonated. I'd be surpised if that were really what's going on.

 

The detonation is kind of a chattering sound accompanied by a noticible drag on the engine. If you let off the gas a little the chaterring goes away. Almost as if it was like a regular engine and if you advanced the timing to much you'd get valve clatter.