[s-cars] 1995.5 S6 Running Real Rich, Flooding Under Boost

Scott Houser swhouser at gmail.com
Fri Feb 6 17:29:31 PST 2009


First post. This one is perplexing me, and our indy mechanic {who's good.}
Any suggestions appreciated.
Car has 82K miles, and a lot of work has gone into it to make it right over
the past year. Car has an IA Stage III+ chip {their term},
Samco hoses w/Breeze CT clamps. New 034 MAF to Turbo Hose. {All mods are
with 5K miles}

We had a couple of dying coils, and decided to go with an O34 HO coil kit
after a lot of thought. After installation {a week ago}
we had lots overboost. Found a tiny tear in the WG diaphragm and replaced
it. That was after checking, and swapping with
another car { one of our shop's tech's has an S4} the N75, the BPV, the ECU,
the Fuel Pressure Regulator, and testing the coolant sensor, knock sensors,
the MAF sensor, etc.  O2 sensor was new 5K miles ago. New Fuel pump and fuel
filter, as well.

Right now the car will pull very smoothly, under load, to 6000rpm as long as
you stay out of boost. With more than 5 psi, the car stumbles, and is held
back. It floods, and is obviously dumping unburned fuel. A ton of black
smoke. Very strong fuel smell. Pull the plugs and they're black with soot.
We've pressure tested it to 20 lbs., and it holds for 5 minutes {maybe
drops 1 lb.}. The car's been smoked. No leaks show. Sure sounds like a boost

I'm away on business, and won't get to the car until next week. It's at my
mechanic's. He's real good and knows Audi fuel delivery systems inside and
out. He's stumped, and so am I. I guess that the next step is to pull, and
re-tighten all of the Samco's, to make sure. I would have guessed a blown MM
hose, but that's not it. I have a metal crossover pipe on the way, but the
plastic one looks fine. The intercooler tanks are OK, but I'm replacing with
an aluminum S4 IC.

Any suggestions and ideas of what to look into much appreciated. As my tech
says, "there has to be one tiny thing that I'm missing."  Thanks, very much.

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