oright i have a 1989 escort rs turbo and its running about 6 psi of boost and when i boot it and let of the revs it cuts out does anybody know why it does this, car is standard by the way apart from full mongoose system. , doesnt do this all the time just sometimes any body know why.

 

My old Series 2 used to do this once i had it set up it was fine after never cut out again


brian

 

Mine did this with a knackered dump valve. Once booted, it would keeo the valve open and create a massive air leak. I replaced that and has been sweet ever since.

If you havent a d/v fitted, i'd take a look at the boost hoses and make sure all jubilee clips are tight.... maybe on boosting the hose is expanding allowing air to be lost via a loose clip.

 

Could be running rich on overun, fuel ECU, EMPA, or TPS, try leaning out your idle mixture a little bit if what Marts said doesnt cure it.