It's
Audi® Duty Time: A Quattro® Quandary
Audi®
Quattro®…Engine Loses Power or Misfires
Sometimes,
what is seemingly a complex problem can have the simplest
of solutions…if you know where to look! Such is the
case with this Audi® Quattro® "power loss
/ misfire" problem. Let's say you have the owner
of a 1992 Audi® Quattro® standing at the front
counter. He says his car has developed a loss of power
and occasionally misfires on acceleration. Of course,
the first thing you think of is that the fuel filter or
air filter is plugged or maybe an ignition part is bad.
Or maybe…
Then
you find out that the owner has just replaced the fuel filter,
air filter, spark plugs, ignition wires, distributor cap
and rotor - with Audi® factory parts, and he seems to
be mechanically adept. Now the plot thickens. The next logical
question you pose to him, as you scratch the stubble of
your burgeoning goatee, "Did this problem start before
of after you replaced those parts?"
You
were secretly hoping he was going to say "after"
weren't you? No luck - The reason he replaced the parts
was because he thought a thorough tune-up would eliminate
the existing problem. "Rats!" you think. "It's
NOT going to be one of those easy to diagnose jobs."-
Or is it?
 Looking
at the technical service bulletins (TSBs) in your automotive
information system (online or disc-based), you find a TSB
that describes his vehicle's symptoms perfectly. According
to Audi®, some 1988-92, Audi® 2.3 liter, 5-cylinder
Quattro®'s may exhibit a loss of power and/or an engine
miss because of low fuel flow. The cause is a restriction
at the inlet banjo bolt on the fuel distributor. (See
diagram left.)
The
culprit, in this case, is a mini-filter inside the banjo
bolt that can become partially or completely clogged. This
filter was supposed to be replaced every 7,500-miles. Sometimes
these filters were overlooked, the parts departments quit
carrying them or they became prematurely plugged due to
a high amount of contaminants in the fuel tank.
The
fix is to replace the old banjo fitting (with filter)
with a new type.
 Note:
There are two different types of banjo fittings.
(See illustration on the right.)
1.
If the hex head of the banjo bolt has a raised shoulder
(A), it contains a mini-filter.
Replace mini filter with a new type banjo bolt. (Part No.
N0210712)
2.
The hex head of this banjo bolt (B) does not have a raised
shoulder and does not contain a mini-filter. This is the
one you want to use.
Taking
a print out of the TSB to the car, you quickly identify
the old type banjo fitting. After installing the new style
banjo fitting, you test-drive the car and the problem
is solved. Unfortunately, the owner spent a lot of money
replacing parts that might still have been serviceable.
On the other hand, when he finds out what the problem
was and how you professionally diagnosed it, he probably
will give you all his future repairs. Now wasn't that
easy?
Written
by ALLDATA Technical Editor, Rich Diegle.
Rich is an Advanced Engine Performance Certified and ASE Master Technician with
an Associate of Arts degree in automotive technology and 22 years of dealership
and independent shop experience.
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