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

[n-engelbert at terrans.net]

Cap, rotor, wires, and plugs were new last fall.

Nathan

> Nathan-good luck getting this sorted.  My tach only jumps during a hot
> start, never during a cold start-strange...  I really hope it's not the
> ECU,
> but then again, if you needed a reason to hasten your 3B upgrade....
>
> How new are your plugs/wires?  Now that I think about it, I was getting a
> bit of a weak spark during hot starts, and the motor would crank and crank
> until it was cool enough to start.  I replaced the plugs, wires, cap and
> rotor, and it does start much better now when warm.  Sorry I didn't think
> of
> this before.
>
> Best,
> Jim
>
> -----Original Message-----
> From: n-engelbert at terrans.net [mailto:n-engelbert at terrans.net]
> Sent: Tuesday, July 26, 2005 4:29 PM
> To: Pasqualoni, James E
> Cc: urq at audifans.com
> Subject: RE: [urq] No hot start (speed or reference sensor?)
>
> It's possible that I'm vaporlocking as well, but this is even almost
> immediately after shutting off the car.  The fuel pump was replaced last
> year with a Pierburg unit.  This pump has an internal check valve.  The
> car
> restarted great for a month or so after I replaced the failed bosch pump
> (in
> the parking lot, at an autox), and then restarting got bad again.
>  I'll pop the fuel pressure gauge on and see if pressure is bleeding off
> again.  Or, I could jumper the fuel pump relay closed with the car off,
> let
> it sit for a few minutes artificially holding pressure, and see if it
> restarts more easily.
>
> Anyone have an inline check valve that they're using?  I'm thinking
> something like the valve at the bottom of page 357 of the online McMaster
> Carr catalog.
>
> But, the tach will not move at all when cranking hot.  Then, all of a
> sudden, the tach will move while cranking, and the car will start.  Maybe
> it's all in my head.
>
> Sorry for the long reply, there will probably be more while I try to track
> this down.
>
> Nathan Engelbert
> 83 UrQ DA900453
> 89 90q
> 91 200q20v donor
> 91 200q20v avant
>
>> 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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>