Hi ppl.. My car (1991 Series 5) is running without an air pump (since purchase) and while I was taking out the turbo yesterday to fix some leakage, I found the 'rat nest' (ACV) was in the way so I had it removed as well. I've read from the archieve that it is most common to remove both the air pump and ACV at once but I have no idea why my ACV has been left in place.

This morning, during cold start, the car couldn't hold its rev at all and will die off the moment it cranked up. I had to hold on the throttle manually to keep the rev up until its warmed up only it will idle. THe idling of the car now became very lumpy.. especially during the A/C compressor turning On/Off.

Also, I've noticed the car backfires much more now but thats not much of my concern. From my understanding, the ACV actually helps counter afterburns. Correct me if I'm wrong.

Could someone pls help with this annoying idling issue? If I have to adjust the idling which or where should I be fiddling round?

Thanks

 

So the ACV got removed. That in itself should not have caused ANY problems. What you problem is, is that whatever type of blockoff plate that was used to replace the ACV, is probably leaking air into the intake. So make sure your blockoff plate has a good gasket and does not leak.

I've run without the anti-afterburn part of the ACV active, and I've never experienced a backfire. Even without a ACV altogether I've never experienced a backfire.

By the way, I'm getting ready for emissions today. I reinstalled my ACV and started the car up. Ran ratty at idle. OOOOps. I forgot to reinstall the purge hose with the silver checkvalve back into the turbo inlet duct. Shame on me. Real crummy idle without the checkvalve/hose installed. Open hole. Unauthorized air leak. Sounds similar to what you described.

 

Hailer: COuld u pls describe to me which is the purge hose?? I'm quite certain that the blanking plate I have with proper gasket and sealant is sealed fine... But seems to me like some sort of vacuum leak.. I'm totally lost! Btw, I don't even have a cat converter and the exhaust goes straight through into my apexi N1 exhaust extremely environmentally unfriendly.!