- Feb 28, 2011
- Vacaville, CA
I'm having a hell of a time getting my GVR4 dialed in. I've been having an issure with part throttle knock. As soon as I build any boost at part throttle, the knock counts jump up. I can peg the knock counts at 43 with 2psi on the gauge, and about 30% throttle. I don't think it's phantom knock, because I can repeat it at will. With heavier throttle, I usually get minimal knock. I'm running a 20G at 20psi with 750's a 3G (#482) MAS, and a SAFC on 91 octane. I know that the set up will not be easy to tune, but this part throttle knock started fairly recently. I've tried adding and subtracting fuel. My fuel trims are just over 100 for the mid and low, low 80's for the high. The power delivery on the car is aslo very choppy when I go WOT. It's worse in lower gears. When I step on it in first gear, I get a brief surge of power, then it falls on it's face while you can hear the turbo spool, then it takes off again. The car is very inconsistent, but it usually feels good at mid throttle, then falls flat when I floor it. I've checked for boost leaks, and swapped out the knock sensor. Any ideas? I've been working on this for the last couple months and I'm getting nowhere.