RockyMountainS4

So I have an '01 S4 with 90k miles on it. I had the turbos go out on me before and replaced them with used ones that had 50k on them by someone upgrading to Porsche turbos. The car is chipped, can't recall which.

The car idles pretty fine and even under light throttle (still in vacuum) it runs smooth. The second it exceeds 0psig it falls flat on its face. No CEL gets thrown. In my past experience when the turbos "blew" it was more of a stuttering accompanied by a squeal like a banshee. It was in fact drivable, although that's a stretch of the term. I did a pressure test and found a pretty big boost leak on the DS IC. Fixed that and found no other leaks. No change in symptoms. No CEL.

So I've just let it sit for awhile and now need to decide whether to get it running and see if anyone wants a nice Nogaro S4 or build it up a bit more and keep it. But while I've put off rebuilding the turbos or putting in rebuilt or upgrade ones for a long time now, as pulling the engine and tranny again isn't so fun, as I begin to look at my current options I still have this nagging feeling it isn't the turbos.

While the DVs seem to be fine, in fact I may have replaced them, I suppose its possible that while pressure testing they stay closed that something is causing them to open the moment any boost is seen while the car and engine are running? That seems quite the stretch of a hypothesis. And the fact the car isn't throwing any codes is only bizarre, to me. I've obviously been through clearly 'without a doubt' blown turbos before and this has never given me that clear and distinct impression.

I'm open to any thoughts and input, please Hedging my chances and doing a turbo swap (or any model) when unneeded and speculative really doesn't sound appealing.

What else can/should I test to better pinpoint the problem?

(Plus I have to balance practicality of resale between stock and upgrading to K04/etc and hoping the buyer desires such and pays the premium. In my experience, upgrades are often a crapshoot on resale value. I have B7 RS4 reps never installed, along with Vogtland GT3s still in the box, along with another $1-2k of parts that got delayed in install due to this problem, and yet most craigslist buyers won't pay a penny on a dollar for their value lol)

RockyMountainS4

Anyone?

Ran it again today after a nice warm up period and clearing the ecu.

Present symptoms

• Idles fine
• Nearly, or completely, stalls when opening the throttle to any degree that tries to build 0.001+ psi of boost

Non-present symptoms

• No smoke
• No whine/banshee
• No on boost/off boost perpetual stumble
• No low-boost akin to limp-mode
• No codes thrown
• No leak with pressure tester @ 20 psig

I'm stumped, and I'm oft quite good at these sorts of gremlins

Beers and heartfelt thank you for whomever points out what I'm missing that turns out to be the culprit

Chris Lambert

Boost leak, lost FPR pressure reference line, clogged fuel filter, ignition/plugs; the list of possibilities is fairly large.

RockyMountainS4

Swapped ICMs and it fixed it [although putting the old ones back didn't unfix it] so who knows.

Now I have an odd code thrown and massive oil burn :: http://www.audizine.com/forum/showth...or-Correlation

Case of this thread however seems solved. Thanks for the insight; and it was such an enormous list of possibilities that it made determining a devil. In hindsight, if only my current problems were so benign as this was.