poor warm start + engine racing - 5kcstq - the fix

[Ben Swann]

Well I probably shouldn't publish the results of my findings prior to 
absolute verification that the problem won't recur, lest I jinx myself, but 
I am fairly confident I found the problem.

IGNITION SWITCH!

That explains why for months now my wife would complain that the car 
wouldn't start when warm.  Then I'd have her get out of the car, turn the 
key and starts right up. "Honey, I guess you just don't have the right 
touch."

Well,  it seems the switch was not providing ignition when the starter was 
engaged - depending on how far you turn the key, how long you cranked, and 
when you released it.

Of course it had all of the signs of pressure leakdown or warmup regulator 
misbehavior.  Which led me in the wrong direction of troubleshooting. 
 Friday, for some reason seemingly related to my futzin' around, even 
though the car started - sometimes - the ISV circuitry did not register and 
would open up the ISV full tilt.

Oh, I actually got into troubleshooting when the wiper spritzer didn't. 
 Seems electrical gremlins were popping up everywhere, but I didn't connect 
the dots.

Anyway, I finally hit upon the flaky switch, and now have it bypassed using 
a 4kq switch, which has been working fine, and the problem has not 
duplicated despite my efforts to recreate the fault.

New switch from the dealer goes in this afternoon.

Don't know what lessons learned, except that it isn't always what it 
appears to be.  Certainly not the first time, but it helps to know what has 
been replaced, and not to let compound failures creep up and really 
confound the diagnosis - eg. keep in good tune and fix stuff right away 
when it is marginal or failing, in this case, I'd already been through 
injectors, ISV, vacuem lines, the works, etc.

Cheers!

Ben

On Friday, March 15, 2002 3:15 PM, Ben Swann [SMTP:bswann at worldnet.att.net] 
wrote:
> Troubleshooting combined 5ktqw warm start problem compounded by ISV open 
on
> startup(engine racing).  Problem started as a warm start problem getting
> progressively worse(perhaps because spring weather is here).
>
> Car always starts right away cold.
>
> After engine warmup complete, come back in 10 min - 1hour and car will 
not
> start.  Set a few minutes and fires right up.
>
> No vacuem leaks.  New injectors. Timing belt, etc done recently.  Ran 
some
> BG44K through a couple weeks back.  Worstening problem has prompted me to 
> start troubleshooting. I didn't watn to get into fuel pressure/leakdown
> tests - yet.
>
> Now here is what I messed with - my Audi certified tech friend insisted 
it
> was the pressure relief valve(and not the warmup/control pressure 
regulator
> as I had suggested).  I removed the assembly  pressure relief assembly 
and
> saw nothing visibly worn or dirty, cleaned thouroughly and replaced.
>  O-rings were in perfect condition.   I allowed the system to run fuel 
out
> the hole prior to reinstallation.
>
> After that, the car started and idled very slowly around 500RPM and I
> adjusted throttle screw to 800RPM.  Engine ran fine.  Revved several 
times
> to make sure engine idle stable and allowed the engine to warm up.
>
> I shut off and restarted, and the engine revved to ~2500RPM - what the!. 
 I
> could not adjust down with throttle screw, but was able to drop idle by
> disconnecting ISV.
>
> Duplicated situation by reconnecting ISV, shutoff and restart then high
> RPM.  I don't see how anything I did could effect the ISV operation, so 
is
> this a coincidence?
>
> After engine cooled down later, it started with great difficulty, but I 
did
> not have the ISV problem repeat.
>
> Any clues - please don't suggest it is a defective ISV, unless you are
> quite certain - I have a spare I can swap out with to be sure.  To me it
> would seem more like the ISV control unit or circuit is on the fritz, and 
> may be contributing to the warm start problem too.  Just looking for some 
> leads.
>
> TIA.
>
> Ben