A6 Intermittent Starting Problem

Dear All

Some time ago I posted about my A6 2.4 Auto that has an intermittent
starting problem (details below). Since then, my garage (an independent
Audi specialist) has checked over all of the obvious things (spark
plus, cleaned the injectors etc), however the problem persists and next
week the car is booked in with them to have the fuel pump replaced -
purely on a speculative basis. However, I have been in contact with
another A6 owner whose car had a similar problem, and his was diagnosed
as a faulty immobilizer.

I'm now wondering if replacing the fuel pump is the right thing to do
at this stage. The biggest difficulty is that the problem is almost
impossible for the garage to reproduce (happens about once a week), so
it's very difficult for them to know where to start. From my notes
below, can anyone suggest any components that are definite candidates
for replacement or any that can almost certainly ruled out as the
culprit?

=B7 A typical scenario is that the car starts fine in the morning, and
I park at work after a 20 minute drive. Come to start the car in the
afternoon - nothing. The engine cranks over fine, but doesn't fire
up. I can normally get it started using full throttle and cranking over
for periods of 30 seconds or so. Sometimes the engine will fire after
just a couple of cranking periods, but on one particularly grim
occasion it took 10 minutes.

=B7 Another scenario is that I drive somewhere (short or long distance)
stop for a few minutes and then try and restart and it won't.

=B7 When the engine finally starts after a problem start incident, it
doesn't roar in to life straight away. Rather, I can sense it firing
but know that if I stop cranking it will die, and have to pump the
accelerator to coax it in to life.

=B7 Once started, the engine runs perfectly. No sign of any trouble at
all.

=B7 There are NO fault codes being logged.

=B7 The dashboard immobilizer light does NOT remain lit when the car is
having a problem starting.

=B7 The most annoying thing is that the problem is very intermittent
(say once a week on average) and most of the time the engine starts
fine. I started to keep a log of when it happens but there doesn't
seem to be any obvious pattern.

Thanks very much folks!

Cheers - Graham

Hi Graham,

What year is your A6?

A no start scenario could be the hall sender but that would thro a 2113
code. If it's the immobiliser, check for a faulty relay. I have a C4 S6 and
relay may be behind panel under steering column.

Tony

> wrote in message
ups.com...
Dear All

Some time ago I posted about my A6 2.4 Auto that has an intermittent
starting problem (details below). Since then, my garage (an independent
Audi specialist) has checked over all of the obvious things (spark
plus, cleaned the injectors etc), however the problem persists and next
week the car is booked in with them to have the fuel pump replaced -
purely on a speculative basis. However, I have been in contact with
another A6 owner whose car had a similar problem, and his was diagnosed
as a faulty immobilizer.

I'm now wondering if replacing the fuel pump is the right thing to do
at this stage. The biggest difficulty is that the problem is almost
impossible for the garage to reproduce (happens about once a week), so
it's very difficult for them to know where to start. From my notes
below, can anyone suggest any components that are definite candidates
for replacement or any that can almost certainly ruled out as the
culprit?

· A typical scenario is that the car starts fine in the morning, and
I park at work after a 20 minute drive. Come to start the car in the
afternoon - nothing. The engine cranks over fine, but doesn't fire
up. I can normally get it started using full throttle and cranking over
for periods of 30 seconds or so. Sometimes the engine will fire after
just a couple of cranking periods, but on one particularly grim
occasion it took 10 minutes.

· Another scenario is that I drive somewhere (short or long distance)
stop for a few minutes and then try and restart and it won't.

· When the engine finally starts after a problem start incident, it
doesn't roar in to life straight away. Rather, I can sense it firing
but know that if I stop cranking it will die, and have to pump the
accelerator to coax it in to life.

· Once started, the engine runs perfectly. No sign of any trouble at
all.

· There are NO fault codes being logged.

· The dashboard immobilizer light does NOT remain lit when the car is
having a problem starting.

· The most annoying thing is that the problem is very intermittent
(say once a week on average) and most of the time the engine starts
fine. I started to keep a log of when it happens but there doesn't
seem to be any obvious pattern.

Thanks very much folks!

Cheers - Graham

Thanks for your replies! My A6 is a 1998, and there are no fault codes
being logged. I've just heard back from the A6 owner who had a similar
starting problem that turned out to be the immobiliser, and his car
didn't log any fault codes nor did the dashboard immobiliser light stay
illuminated. So immobiliser is still in the frame - or the relay
(thanks Tony).

BBO, if the fuel pump is the culprit, is it plausible that there would
only be a problem at startup? I'd have thought that the car might
suffer from other problems - poor running perhaps?

Cheers - Graham

In case anyone else has a similar problem, the faulty component was the
coolant temperature sender.

wrote:
>
> BBO, if the fuel pump is the culprit, is it plausible that there would
> only be a problem at startup? I'd have thought that the car might
> suffer from other problems - poor running perhaps?
>

Now that you have it sorted, there's no need for this tidbit - The fuel
pump on my 80q worked fine after it got to working. Not a problem,
when it was actually operating. But it was getting it to get going
that was the hassle. Replacing it solved our intermittant non-start
problem.

Good to hear you got it figured out, and relatively cheaply, too.

E.P.

"" wrote:
> wrote:
> >
> > BBO, if the fuel pump is the culprit, is it plausible that
> there would
> > only be a problem at startup? I'd have thought that the car
> might
> > suffer from other problems - poor running perhaps?
> >
>
> Now that you have it sorted, there's no need for this tidbit -
> The fuel
> pump on my 80q worked fine after it got to working. Not a
> problem,
> when it was actually operating. But it was getting it to get
> going
> that was the hassle. Replacing it solved our intermittant
> non-start
> problem.
>
> Good to hear you got it figured out, and relatively cheaply,
> too.
>
> E.P.

Hi Graham,

I own a 1998 Audi A6 1.8L. I have the SAME EXACT immobiliser problem!

My worst experience was being stuck in a car park for three hours as
the immobiliser light was flashing away.

You mentioned that the issue was with the Temperature Coolant Sender.

Please could you elaborate?

Many thanks,
Lee

--
Posted using the http://www.autoforumz.com interface, at author's request
Articles individually checked for conformance to usenet standards
Topic URL: http://www.autoforumz.com/Audi-A6-In...ict126296.html
Visit Topic URL to contact author (reg. req'd). Report abuse: http://www.autoforumz.com/eform.php?p=638100