1990 Coupe 2.3E 10v - jerkiness/poor driveability

[Marcus Oxer]

Hi Dave,

I confess that I have suspected my ISV in the past when I have had a varying idle problem. However, even when I unplugged its electrical connection, it didn't seem to make any appreciable difference to the running of the engine. I was expecting lots of accidental stalling without the ISV in play but this didn't seem to happen. Might that mean that my idle speed is set too high - above the level at which the ISV takes over?

Apologies if I am not understanding it properly...!

Marcus

----- Original Message -----
From: Dave Kase <davekase at pdqlocks.com>
Date: Wed, 18 Dec 2002 10:08:59 -0500
To: "''Marcus Oxer''" <mdoxer at mail.com>, "quattro at audifans.com" <quattro at audifans.com>
Subject: RE: 1990 Coupe 2.3E 10v - jerkiness/poor driveability

I'm thinking ISV.

Check www.20v.org for the cleaning instructions.

Dave K.
'90 CQ 20v

-----Original Message-----
From:	Marcus Oxer [SMTP:mdoxer at mail.com]
Sent:	Wednesday, December 18, 2002 9:31 AM
To:	quattro at audifans.com
Subject:	1990 Coupe 2.3E 10v - jerkiness/poor driveability

Dear Listers,

I wonder if you can offer any ideas on the following? It seems to have
confounded both my local Audi dealer and a Bosch Injection specialist...

The engine has recently started bucking, or jerking under very light
throttle openings - both as I go on the gas, and as I come off it. If I
hold the throttle in the same position, the car will continue bucking in a
most unpleasant way. Putting my foot down seems to smooth everything out -
it's really only a problem if the throttle is held steady with the car
under light load.

With the car at standstill and out of gear, I have noticed that if I slowly
build up the revs it is quite smooth up to 1800 rpm, at which point it
starts to stumble and miss beats in quite a random way.

I have recently replaced everything on the HT side - spark plug leads,
distributor cap, rotor arm, in order to cure a different under-load
misfire. The spark plugs have just been replaced as part of an Audi dealer
service.

My Bosch specialist said that the (non-original) replacement spark plug
leads might be causing a problem as he has seen cases where they are
insufficiently suppressed and interfere with the ECU. I have reverted to
the old leads but the problem still persists.

Reading through the archives, I am wondering whether components such as
ISV, throttle position switch, and oxygen sensor could be implicated.
However, I am not getting any error codes and also I presumed these are the
sort of things that would have been ruled out by the Bosch engineer. He
charged me ?55 GBP for a diagnostic check, but couldn't find an obvious
fault.

Any ideas would be gratefully received!!!

Marcus Oxer
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