[20v] Coupe Quattro 20V Carbon Fouling Plugs

Ben Swann benswann at verizon.net
Fri Sep 11 11:00:43 PDT 2009

I almost sounds like the fuel pressure regulator is working overtime and may not be
regulating fuel properly to the rail - too much fuel pressure at idle.  This is at least
one possibility and has been seen before on the 7A.

You definitely want to pressurize the rail with fuel whil not installed in the head
(jumper pump on with relay, or just turn engine over to bump FP for a few sec.) and see
if there is some sort of leak when engine not running.

Be careful with fuel and put rail over large container to collect any spry or leak.
Fire Extinquisher on hand!


[Date: Thu, 10 Sep 2009 22:56:17 -0400
From: "Brett Fairbanks" <brettfairbanks at verizon.net>
Subject: Coupe Quattro 20V Carbon Fouling Plugs
To: <quattro at audifans.com>
Message-ID: <004e01ca328b$70b78a00$52269e00$@net>
Content-Type: text/plain;	charset="us-ascii"

I can't seem to get my early build '90 Coupe Quattro project sorted so I can
drive it.  The car starts O.K. when cold, but doesn't want to idle.  I've
swapped in two other idle stabilizer valves, but they behave the same way.
It seems like the car is choking on fuel.  I've found fuel puddles in the
intake and in the rubber intake boot.  Checked spray patterns on the
injectors when I installed new fuel injector seals and all the injectors
were pulsing and spraying a decent pattern.  I've tried to clean up all the
vacuum leaks I could find.  Air intake is unrestricted.

The car will rev fine, but a little stumbly until it warms up.  Makes good
power underway, and the idle cleans up a little after it's hot.  Still, as
the plugs continue to foul, the idle situation degrades until the plugs have
to be replaced.  I have to put the pedal to the floor (flood clear mode) to
get the car to re-start when it's hot.

Any ideas?  I'm getting frustrated as I need to be able to get this car on
the road.  Anyone run into this on their 20 Valve in the past?  Any
suggestions are truly appreciated.


Brett Fairbanks

Delaware, Ohio]

More information about the 20v mailing list