Again, when it rains it pours!! bad throttle switch? AGAIN

Louis-Alain Richard laraa at
Thu Dec 14 22:15:18 EST 2006

A similar event happened to me last week, albeit on my urQuattro that uses 2 of
these switches: WOT and idle. 

The original 24 years old idle switch was flaky, the engine would idle
strangely, but I had a spare set in my parts bin, from a southern car with low
mileage that was converted to EFI (to correct a supposed insolvable 4000 rpm
cutout, which is notorious on urQs). 

On the bench, both switches were OK. But in the car... After a 5 minutes road
test, the WOT switch would stick ON, and the 4000RPM cutout was there, a problem
I hadn't before the swap. 

Conclusion ? An old part may test OK at normal room conditions and behave
strangely under hood. You may want to carry an ohmmeter to diagnose the suspects
when the problem occurs, as I did to pinpoint the flaky WOT switch.

Conclusion #2: the lister that gave me his old parts (when he converted his car
to 034EFI) may have save a bundle by carrying such an ohmmeter...

1983 Quattro
PS: one of the urQ switches is 411 927 211, which means it was designed for the
first generation of CIS VWs, the 1968 type 411. Wow, that is old stuff :-)) 

-----Message d'origine-----
De : quattro-bounces at [mailto:quattro-bounces at] De la
part de L DC
Envoyé : 14 décembre, 2006 11:25
À : audi at
Cc : quattro at; Rennkafer at
Objet : Re: Again, when it rains it pours!! bad throttle switch? AGAIN

Call it irony, call it rain, obviously the cause is
rain (H2O)!!

This morning as I'm driving to work on the highway and
just a block away from the toll, the '85 VW QSW (JT
code engine) starts to exhibit the same behavior after
driving under the rain for some 30 minutes.

Car starts to loose power and sputters and I can not
rev engine.

I pulled over, 1/2 block shy of the toll, to fix the
problem: ZIP TIED the WOT switch (the one on top of
the throttle body) and I'm back in business. It's nice
that is a quick and easy fix.

But, what sensor is getting wet or humid that's
causing the culprit?

Car runs very nice and very smooth on non rainy days
and smooth on rainy days with WOT switch ZIP TIED.

Oh, the irony, last time the problem first happened
was also on a rainy Thursday on my way to work on the
same highway a little over a month ago.

Funny thing I told my brother this morning, "I hope
the car doesn't start with its jerkiness since it's

His response, while laughing was: "Your car is just
like grandpa, he doesn't like to go out in the rain."
Thanks in advance.



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