So I am racing a Mustang Cobra last night. Launch hard, start walking away from him in second, go to third and continue pulling away until I hit 3500 rpm and the engine refused to rev any higher. What the??? The boost gauge read full boost and after I backed out and slowed for the light all is normal again. Never had the problem before and tried half a dozen more boost tests last night and all is well. Seems like the ECU just up and decided it didn't want me to go faster for that one run. The motor still ran smoothly, just wouldn't accelerate. No error codes. It was a cool last night but I was still only pulling about 10.5 pounds.

Oh yeah, I had about 8 car lengths on him when my car decided it didn't want to go any faster. Maybe it was afraid to embarrass him too much?

 

What year mustang was it, the bastard 80's model? Just kidding.
I haad a similar thing happen to me while drag racing. I was cruising through 1s, 2nd, and half way through 3rd when the car just didn't want to go any faster. It was very dramatic, I think I sufferred a slight case of whiplash from it. My boost went to 10 psi to 12 inches of vacuum within split second.

I blame it on a fuel cut. I can't figure anything else that it could have been. As for why I'm not sure. I think that my boost gauge imust not be telling the truth when it says 10 or 11 psi. I think it's more like 12 psi.

 

My car held boost because I checked the gauge when it stopped accelerating. It was just as if I had backed out and held it at 3500. It just stopped gaining speed, it wasn't like the power just died. If it was overboost I thought fuel cut didn't hit until high RPM?