First of all, I've done a forum search on this topic but can't find anything that is related to mine.. so here goes..

My S5 turbo came without an air pump (removed). So while removing the turbo, I junk the ACV altogether. Now I'm having bad idling problem and prob idling at all in the morning. If I don't step on the throttle manually, the car will just die off when its cold. But things go back to normal after its warmed up.

Just want to find out, does the ACV has anything to do with this? I do noticed my car backfires more without the ACV's anti afterburn function. But how can this causes rough idling? So I tried unplugging the BAC valve while the engine is idling; no change in idling speed. Tried clamping the bypass hose on the BAC, no change in anything also... Isn't this the valve that control cold start and stabalising the idle when switching the A/C On & Off??

ANy help is very much appreciated as the car was idling perfectly b4 I took out the ACV... !!

 

ACV only has to do with emissions. The only way your ACV could affect idle is if you did not seal it off well enough with a block off plate. There is one corner that is more succeptable to leaking (the one that doesnt have a bolt there).

The problem with not idling cold is most likely related to the thermowax on the tb. The BAC helps maintain idle under load from PS and AC.

Try taking off your blockoff plate for the ACV again and use some liquid gasket. I used black RTV and it was fine.

 

Thanks mate.. will try that later.

Guess its just a coincidence that the idling prob came after I removed the ACV. My blanking plate has got paper gasket with silicon sealant.. will double check that later.

 

is it ok if your car does that?? Cause mines has the same problem but its bieng doing that since i bought the car in August.

 

Its definitely not OK as the car was idling perfectly ay 750 +-25rpm when I got it...