[urq] No hot start (speed or reference sensor?)

[Pasqualoni, James E]

Guys, please correct me if I'm wrong, but I believe there are reference
marks on the flywheel that determine when and where to spark.  If you are
able to visually check for spark, and there is one, it is possible you've
got fuel vapor lock at the injectors.  I also get this from time to time...

HTH,
Jim

-----Original Message-----
From: urq-bounces at audifans.com [mailto:urq-bounces at audifans.com] On Behalf
Of n-engelbert at terrans.net
Sent: Tuesday, July 26, 2005 4:06 PM
To: urq at audifans.com
Subject: [urq] No hot start (speed or reference sensor?)

Recently on my 83 UrQ DA900453, the car has started fine when cold, but will
not restart when hot.  When cold, the tach bounces as I'm cranking,
presumably at the speed the engine is cranking, but when hot, the tach does
not bounce, I don't believe I have spark, and consequently, the engine won't
start.  As of last fall, the fusebox (under dash) and ignition switch were
new.  Spring 2003 the transistorized ignition switch in the glovebox was
new.  Once I can get the engine to start, though, it runs as if nothing is
wrong, leading to the belief that I may have a flaky sensor.

The question is:

Is there a sensor that the ECU only uses when cranking to determine TDC, and
therefore, when to spark?  This sensor would drop out of operation once the
engine is started.  I'm going to stop by radio shaft to pick up some freeze
spray to bring the offending sensor back to cold on hot restart until I swap
in my 3b sometime after the CT UPG.  I skimmed the IST documents and didn't
see anything on my first time through.

Does anyone else's car's tach bounce when cranking?  Should it move when
cranking?  My 90 and 200q20v's tachs don't bounce that I remember.

The car's been in storage for a while, but this happened last fall as well
before I parked it for the winter.  I can check ECU voltage and step through
the IST instructions if I can't find the problem quickly without removing
the ECU (easy, I know).

Man, I need a scope,

Nathan Engelbert
83 UrQ DA900453
89 90q
91 200q20v donor
91 200q20v avant
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