Roojai

Just noticed a flatspot recently. First noticed it after a day working on the car in which I installed an FSE regulator and removed my decat pipe and replaced with the original catted pipe.

The car is a WRX wagon 1994 model with a TD05 turbo and customed mapped scoobyecu.

The car pulls very well up to about 6000rpm, and then just seems to loose a bit of power (drops about 1psi of boost) and then picks up again at 6200 at which time I am normally changing gear anyway. It is quite consistent, happening NEARLY every time but not EVERY time and the gear I'm in does not seem to make any difference. Sometimes it seems to happen at 6200rpm - 6400rpm.

I thought that it must just be my plugs and that I just hadn't noticed it before the work I did on it.

I changed the plugs today in the freezing cold (brrrr) and although the car does feel a bit smoother it still has this flat spot. the coils are only 1.5 years old so I think they are fine.

any ideas what else could cause it.

It is not overboosting, the scooby ecu has a very high fuel cut set on it, and anyway my boost guage shows lower than normal boost levels due to refitted cat pipe (about 15psi - it was at 17psi before in cold weather)

Could it be to do with the FPR. It seems to be working fine, fuel pressure set to 3.0bar (with vacuum tube disconnected).

I have not run the mapped scooby ecu with the original downpipe before - could it be something to do with the map not suited to the cat pipe?

Or is it something else entirely. I could try a dawes to see if that cures it but it feels more like an electrical issue to me as it is on/off/on/off