'95 90qs: Cut Out, Hard Starts, Stall

[Thomas J. Donohue, Jr.]

Just bought a 91 TQA 20v which is doing similar things at coast-down.  Entering
a parking lot, for instance, off the throttle, all of a sudden, the car is not
running.  Can't even tell, except no power steering and the dash is lit up when
I wasn't looking.  An occasional "miss" or momentary lurch when driving under
power has been noted too.  Car has just under 140k and I don't have the complete
history.  Still sound like OXS?  Thanks.  Tom

"Doyt W. Echelberger" wrote:

> I'm not talking as an expert or even an owner of such a new car, but when
> my 87 5kcstq developed the described behaviors, it was eventually diagnosed
> as a failing oxygen sensor. And all the problems vanished with a new sensor.
>
> The oxygen sensor on my car failed progressively. Eventually, it only
> worked now and then, making for erratic performance that varied between OK
> and terrible.
>
> The failure mode resulted in gradual creep of the mixture toward the rich
> side. When it was too rich, it would lose power and sputter and I'd panic
> and look for a place to pull off the road to get out of the way of traffic.
> Sometimes it would die at a toll booth, and I'd have to let it sit for a
> few minutes before it would restart.
>
> Here is a test. When it sputters, FLOOR IT. Flooring it opens up the
> throttle and allows large amounts of air to enter, which temporarily
> provides air to the rich mixture setting, and the power returns for a
> little bit.....3-4 seconds, or as long as the throttle is wide open.
>
> If flooring it helps, you are probably dealing with a rich mixture, and
> that might be due to a failing oxygen sensor. Then you can go to the
> expense of having a mechanic use a special instrument to test the cycling
> frequency of your oxygen sensor. Or if your sensor is over 30k miles old,
> you can just replace it.
>
> Doyt Echelberger
>
>  >>>>>>>>>>>>>>>>>>>>>>>>>>>
> At 12:04 PM 8/27/2000 -0400, you wrote:
> >Hello,
> >My 1995 Audi 90q (73k miles) has a real problem. It started
> >as the occasional stall at idle, then progressed to quick,
> >intermittent cut out while driving. Now, at road speeds, the
> >engine will sputter rapidly and die altogether, and be
> >nearly impossible to restart. Car backfires slightly. After
> >letting it cool a bit, I can restart and sometimes run for
> >1/2 hour or more with no problems.
> >At first, I thought that i had gotten a bad tank of gas. Ran
> >some methanol through, with limited, short-term success. may
> >not have helped at all, in retrospect. I am two tanks of gas
> >past that first suspect tank. I have run injector cleaner
> >through before and after this started. All panel indicators
> >are normal.
> >Any ideas?
> >
> >-DanZ
> >
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