hard start issue

[Tony Hoffman]

coolant temp sensor. The one the ECU uses to determine engine temp.

My understanding of the check valve failure with regards to hot
restarts was fuel boiling in the lines, and therefore having to clear
the air out. But, either way, you guys hit it on the head. Hot
starting problems can be caused by it, but I've never seen one cause
cold starting problems (in probably 50 cases I've fixed).

Does holding the throttle open a bit help at all?

Tony

On Sat, Nov 20, 2010 at 4:36 PM, robert weinberg
<centaurus3200 at yahoo.com> wrote:
> i'm not finding anything for an engine temp sensor - do you mean coolant
> temp sensor? or the intake temp sensor?
>
> Regards,
> Robby
>
>
> ________________________________
> From: Phil Rose <pjrose at frontiernet.net>
> To: PeterBergin at aol.com
> Cc: centaurus3200 at yahoo.com; auditony at gmail.com; 200q20v at audifans.com
> Sent: Sat, November 20, 2010 8:26:38 AM
> Subject: Re: hard start issue
>
> At 11:51 AM -0500 11/20/10, PeterBergin at aol.com wrote:
>> Curious, when mine went, the car would cold start but would crank a long
>> time when trying to restart after it sat for an hour.
>> Pete
>>
>
> Same experience here. So, if Rob's symptom is that his car starts fine after
> it's warmed up (i.e., after running it then restarting after a wait at
> *least* 20 minutes to an hour) yet it has a problem starting when dead cold,
> then I seriously doubt that it's a check valve issue.
>
> Why? Well, when the engine is "cold" (after standing overnight or beyond an
> hour after shutdown) the engine temp sensor modifies the start-up to make an
> easier "cold start", and that tends to compensate for the fuel line "leak
> down" issue. But when the engine has warmed up, that special cold-start
> sequence is not used, so any fuel-line leakage will tend to cause excessive
> cranking if there's been enough time for leak-down (20-60 minutes). That's
> the "classic" symptom for a bad fuel line check valve.
>
> Rob, perhaps have a problem with that engine temp sensor. I forget the
> Bentley number (G60?), but think it's a sensor located at the rear of the
> engine (passenger side)--not the MFTS. The same number is used for more than
> one sensor I seem to recall.
>
> Phil
>
> --
> Phil Rose.....Rochester, NY USA
> '06 A3q 3.2 V6 (20K, silver)
> '91 200q    (165K, Lago blue)
> Gone to Audi Valhalla:
> '91 200q  (Tornado red)
> '89 100 (Bamboo gold)
>
>