[200q20v] Mixture....advice needed

Brian.Link at Level3.com Brian.Link at Level3.com
Mon Dec 18 13:24:23 EST 2000

You nailed it Chris,
bosch part number for the 91 3B injector is 0280 150 737
my injector is bosch part number 0280 150 951 which is the S4 injector.
the 3B is at 3.0 Bar the S4 is at 4.0 Bar.
Now what?  will a S4 regulator fit?  I guess I will have to get an
adjustable one.

Brian Link

Boulder, CO

-----Original Message-----
From: C1J1Miller at aol.com [mailto:C1J1Miller at aol.com]
Sent: Monday, December 18, 2000 10:21 AM
To: Link, Brian
Cc: 200q20v at audifans.com
Subject: Re: [200q20v] Mixture....advice needed

I'd start by getting on the phone with RevSport and finding out what the
injectors are, relative to stock.
At idle and low boost, the o2 sensor will adjust the amount of fuel to keep
you near stoichiometric; at partial boost levels on up it is map-driven.

If the injectors flow less, then you'd be running lean.  If the injectors
expect higher fuel pressure (like the urS4/6, which runs about 0.5 bar
higher fuel pressure), then you'd also be lean... perhaps switching to the
urS4/6 fuel pressure regulator is in order?

Could also be the gauge, but that seems unlikely; it probably reacts slowly
when under boost, but will still react.


In a message dated Mon, 18 Dec 2000 12:12:04 PM Eastern Standard Time,
Brian.Link at Level3.com writes:

<< If I have already asked this question then sorry for the repeat.
I need your opinions,  What would cause my car to run lean from about 6psi
up to where I hit the point where I trip the computer to go full rich.  
I've been through Scott M's web site and I think it might be either a vacuum
leak or a bad fuel regulator.

No error codes stored.
New throttle position sensor.
New BV
New fuel filter
recent techron treatment.
new vacuum tubes from BV to IM, from fuel regulator to IM, breather hoses
are soft but solid.

I installed an autometer Air/fuel gauge and I feel this slight stumble when
it goes lean but no missing or stumbling, the car doesn't fall on its face.

could be bad fuel regulator, Is there a place to hook up a fuel pressure
gauge tot he rail?
Could my TAP chip have bad fuel table mapping...not very likely.
I have supposedly different then stock injectors, RevSport installed RC
injectors..I don't now what size.
Vacuum leaks, where is the best place to check.
fuel pump going south?

any advice on my problem is appreciated.  In fact I would have never known I
had a problem if I didn't install that gauge.  Stupid gauge


Brian Link
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