Hard start, cold start problem, rough idle

Bernie Benz b.benz at charter.net
Thu Jun 29 18:48:33 EDT 2006

Derek, Bryan, and others with this problem.

Obliviously there could be multiple causes for these symptoms, but replacing
the O2 sensor solved the problem on my 90Q-20V.

Good luck, and Derek, how did the heater core go? Takes lots of beer and
vocabulary for that one.


> From: "Derek Pulvino" <dbpulvino at hotmail.com>
> Date: Thu, 29 Jun 2006 13:46:47 -0700
> To: brfoster at gmail.com
> Cc: 200q20v at audifans.com
> Subject: Re: Hard start, cold start problem, rough idle
> Bryan,
> It's a possiblity, but only way to know is to pull out the injectors and
> check things out.  I also know on my car that on start up, I do get
> excessive smoke and that could be from bad valve stem seals, but the smoke
> (when I back through it) always has more of a burnt gas than oil
> smell....further reinforcing the "too much gas" theory.
> On my car, the rough running doesn't last for 10-minutes...the inability of
> the car to idle w/out my foot on the gas when warm does.  Usually rough
> running goes away after a minute or so...although yesterday it carried on
> for a couple of minutes.
> Derek P
>> Thanks Derek,
>> What do you think of a single isolated leaky injector?  If the car was
>> sitting for at least 30min it could accumulate enough leaked fuel into the
>> cylinder causing an overly rich mixture on startup - giving a rough idle at
>> startup only.  I dont know why that would last up to 10min in your car
>> however.  It seems to fit my problem of 30-45 sec more.
>> Bryan
>> On 6/29/06, Derek Pulvino <dbpulvino at hotmail.com> wrote:
>>> Bryan,
>>> I've been having the same problem for a while, and notice it also does go
>>> away in the colder months...in fact now that's it's warmer again, when I
>>> restart my car when it's warm, and last ran within an hour to two, the car
>>> won't idle at all without me keeping my foot on the gas...that condition
>>> lasts for at least 10-minutes.  Also notice the rough running when I
>>> restart
>>> the car, lot of stumbling for a couple of minutes and the check engine
>>> light
>>> will come on, but I get no fault codes.
>>> Right now, my key suspect is the idle stabilizer valve, and I do recall
>>> that
>>> when I last pulled it to check, the flapper/valve seemed to
>>> immovable.  Was
>>> going to do an "output test" when I get some spare moments again.  The
>>> only
>>> thing I can think is maybe this is sticking, and causing the car to be
>>> overly rich on warm startup...but it doesn't answer the question as the
>>> why
>>> the car wouldn't also do the same once it's warmed up.
>>> Some other ideas I had was maybe the temp. sensor to the ECU was crapped
>>> out, but resistance at the sensor was within spec when I checked, or maybe
>>> I've got a back check valve which is letting the fuel pressure decline too
>>> much between starting...but then I wouldn't have idle problems for as long
>>> as I do.
>>> All in all, this is quite frustrating and not contributing to a health
>>> demeanor when I'm on the road.
>>> Derek P
>>> Message: 1
>>> Date: Wed, 28 Jun 2006 17:05:45 -0400
>>> From: "Bryan Foster" <brfoster at gmail.com>
>>> Subject: Hard start, cold start problem, rough idle
>>> To: 200q20v at audifans.com
>>> Message-ID:
>>> <9be3f0980606281405v257c1184q199efc0a6c4b9464 at mail.gmail.com>
>>> Content-Type: text/plain; charset=ISO-8859-1; format=flowed
>>> Listers,
>>> I have had a couple of weeks of rough idle during cold start ups.  The car
>>> will start easily, but then idle very roughly for 30-45sec.  After that
>>> time
>>> it runs and idles very smoothly.  If I start it up and immediately rev the
>>> engine to >2000rpm then it runs very smoothly, but if I was to let off the
>>> gas and let the engine slow down to idle then it sputters and nearly
>>> stalls.  When I rev it up right after start up there is a considerable
>>> delay btw putting my foot down and engine response as if the mixture is
>>> way
>>> off.   It seems to happen if the car has been sitting for >1 hour.  Not
>>> necessarily a completely cold block.  Does this point to anything in
>>> particular.  Leaky injector?
>>> Thanks in advance,
>>> Bryan Foster
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