captiva

Just bought a Group A dump valve for my stage 3 Cossie 4x4 and works well but when the engine is idling I can hear air (vacuum) being sucked in through the vent holes in the valve. Is this right?

stevecossy

I have a collins dump valve on my 4x4 and it is slightly open on idle and when ya rev it then it closes allowing boost to build up. Hope this helps mate.

captiva

Sounds right then if yours is doing it like mine. You would think it would make the AFR wrong and get an erratic idle. I have got that but it was there before I fitted the dump valve.

stevecossy

My idle is ok, fitted 1 of these to my mates rs focus and that realy not like it so we went back to the std.
Have you a grp A cone on yours too ? I have k+n and that and dump valve sound great,loud intake sucking noise followed by turbo chatter and dump valve whoosh when come off gas. Smiles 4 miles.

captiva

My idle is alright untill you switch off the engine when hot and start it again and the idle revs to 2000 and the only way to stop it is to disconnect the ISCV and reconnect it. Have done all the checks, cleaned the ISCV, checked for air leaks, set the baseline idle whatever. When I put another chip in ECU it cures it, go figure.