WS6 GreeN

OK, I dynoed my care before LTs and Y pipe and put down 327 and 344 tq. Dynoed my car again yesterday. Temperature was 20 degrees warmer. I put down almost exactly what I put down before the LTs. I went through all 3 atap logs and found that between 4900-5100 RPMs, my KR suddenly jumps to 3.9 then starts going down again, but not fast enough to recover the lost power before the end of the dyno pull. Its odd to me that it was the same RPM range all 3 pulls. Could something be hitting on the bottom of the car causing this KR? I know its false because you can't hear it pinging. Any help would be greatly appreciated. I have Pacesetter LTs ad Y.

Mike K.

I know with some headers the y pipe or even the collector can hit underneath the car but I would think that you could hear this if that was occurring. My dual exhaust knocks sometimes near the rear and I can easily hear it in the car and this is what I'm basing my opinion on. Get under there and check it out. You may be able to see where something was rubbing or if something is close enought to where it could knock.

Gev

So if a y-pipe or header is banging, it can be registered as knock and therefore the engine will pull timing thinking it is knocking and pinging?

avezz28

ttt

Mike K.

I cannot say I know for 100% sure but I would guess If I can hear it that the knock sensor can and would thus pull timing. I believe alot of the false knock posts are related to this.

WS6 GreeN

I can vouch for headers banging causing knock. The car is going to the exhaust shop tomorrow to get looked at. Hopefully they can find a problem.

TaTommyWS6

Did you get a wideband when dynoed? Your tune could be off (too lean causing knocking)...