Originally Posted by tlcoll1

I'm not "blaming" the tune per-se, and I believe you when you say everything was fine 'n dandy when you got the tune. But then you went to the track on a different day, with different weather conditions and drove the car in a way that (I'm betting) was wholly unlike the way the car was tuned. Most tunes are done as a full pull in 3rd or 4th, on a dyno or on the street. That's not how drag racing works, and I've personally seen massive differences between knock on different days and under different circumstances with no changes in the tune. Your tune should have picked up 20-30 HP up top, and instead your drag runs indicate less HP than before. With no mechanical changes and only a short time between tune and drag strip, there's no other explanation other than knock, which I've personally seen zap 50 HP.

Folks that "get tuned" and go out and run great times either have a car that's very knock-tolerant, or they've got a very conservative tune and hit just the right weather combination. As I said, without a good engine management system where you can see what's going on and tweak the tune as you run, you end up just where you are now: "something's wrong" and there's no real way to diagnose what.

Tom