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

[chris chambers]

Scott,

a bad MAF or dirty contacts on the MAF/MAF cable can cause
the ECU to think it's in an overboost situation, normally when
this happens it shuts off the fuel to stop the overboost.

I had this happen to my car, felt like I hit a wall cause the engine
basicly shuts off momentarily due to the shut off of fuel. If I drove
with no boost it ran fine up to redline, but if I accelerated hard
it "bucked" at ~ 4k rpm.

So I'm wondering if the same problem could fool the ECU into thinking
there is more boost than there actually is (but not overboost) and supply
more fuel for the boost it "thinks" is there.

You might want to take some contact cleaner to your MAF sensor's connector,
and to the MAF cable's connector. If you have another MAF sensor you might
want to swap it in, but make sure the cable/s connector is clean and not
corroded.

HTH
Chris




--- On Fri, 2/6/09, swhouser at gmail.com <swhouser at gmail.com> wrote:

> From: swhouser at gmail.com <swhouser at gmail.com>
> Subject: Re: [s-cars] 1995.5 S6 Running Real Rich, Flooding Under Boost
> To: fastscirocco_2000 at yahoo.com, "Audifans" <s-car-list at audifans.com>
> Date: Friday, February 6, 2009, 9:41 PM
> Thanks, Chris.
> 
> Plugs are F5DPOR's.....they were almost new and I just
> replaced them with a second set to be sure. Think we're
> OK there. 
> 
> O2 sensor is almost new. Think that could fail in about 6K
> of driving....a year? Maybe we'll swap that out
> And see. Lee has probably tried that already. 
> 
> Runs very smoothly out of boost, even under load. 
> 
> Thanks. 
> Sent from my Verizon Wireless BlackBerry
> 
> -----Original Message-----
> From: chris chambers <fastscirocco_2000 at yahoo.com>
> 
> Date: Fri, 6 Feb 2009 18:24:50 
> To: <s-car-list at audifans.com>; Scott
> Houser<swhouser at gmail.com>
> Subject: Re: [s-cars] 1995.5 S6 Running Real Rich, Flooding
> Under Boost
> 
> 
> 
> Scott,
> 
> I'd check and make sure it has the right spark plugs,
> plus I'd
> be suspicious of the oxygen sensor as a bad oxygen sensor
> will
> make it run rich.
> 
> HTH
> Chris
> 
> 
> 
> --- On Fri, 2/6/09, Scott Houser <swhouser at gmail.com>
> wrote:
> 
> > From: Scott Houser <swhouser at gmail.com>
> > Subject: [s-cars] 1995.5 S6 Running Real Rich,
> Flooding Under Boost
> > To: s-car-list at audifans.com
> > Date: Friday, February 6, 2009, 8:29 PM
> > Hi,
> > 
> > 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
> > leak.
> > 
> > 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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