Hi can anyone tell me why my car revs crazily when started and only comes down when brake pedal is depressed, if foot comes off brake pedal it over revs again. Recently changed the throttle pedal and the O2 sensor to cure the over revving it has not worked. Thanks in advance

Try unplugging the MAF and see if that stops it

Dodgy CTS, but that seems like a stab in the dark. I would have have initially suggested maybe the throttle pedal sensor, but if that has been changed and the problem remains then maybe the wiring/loom is damaged?

Possibly a vacuum leak, if it's related to the brake system i.e. Vacuum operated servo.

Having said that, the 1.8t doesn't rev with the brake pressed, so it probably is something electrical.

Do you have vagcom? The throttle body may need aligning.

as the 1.8t is a drive by wire system, iirc pressing the brake pedal will kill the engine revs, so it is as if the car thinks the throttle is always being pressed.....? But that said I know nothing about petrols :wonder:

vagcom reports throttle %, iirc so that would be a good thing to check.

I'm getting way confuzed with this, people keep saying the engine doesn't rev with the brake pedal depressed but mine does??? :wonder:

I think it's mainly when you're moving, so you can't accelerate and brake at the same time.

Aaaah PANTS!

I guess that means I won't be doing any left foot braking in my new purchase then!!! :S

you can get it mapped out so you can left foot brake.