Matt200

I've looked at so much crap...but I can't seem to solve my problem.

I have a '91 200 20v, and the engine is in pretty good shape. But whenever I'm on the gas, and then clutch it completely, the RPMs drop down until the car just dies. It does it in every gear too, but most noticeably second. For example, if I'm turning left onto a street, and the streetlight is close enough to stay in second, and I need to clutch it to stop quickly, it dies.

I've cleaned ISV, no vacuum leaks, manifolds are OK, all hoses in correctly. Could it be the air filter? Any help is greatly appreciated.

yodasfro

Possibly a blown bypass valve.

Matt200

You mean like the one on the turbo? How much does that run to replace?

yodasfro

You can get a metal one off ebay for $50ish See the link so you know what you're looking for.<ul><li><a href="http://www.quattro123.com/Audi200BypassValveReplacement.htm">http://www.quattro123.com/Audi200BypassValveReplacement.htm</a</li></ul>

Matt200

I would have eventually figured it out :P

Could this also be affecting my boost pressure? It seems to be running a little low.

yodasfro

Yes it can affect boost pressure too if it's leaking.

Matt200

http://tinyurl.com/3knu5o

yodasfro

to the crappy plastic bosch bpv's.

Matt200

OK. Could it be a sticky hinge inside of my OEM one? Could I just take it off real quick and douche it with some carb cleaner?

yodasfro

Carb cleaner would likely dry out the diaphragm.
You can test it with a mity vac to see if holds vacuum via the nipple on the bpv. If you don't have a mity vac you can remove the valve and push the diaphragm spring open and put a finger over the nipple to see it stays open, kinda like water in a straw.