88 90 Quattro fluctuating idle

Denis Julien sparkplugvw at hotmail.com
Fri Mar 26 15:35:24 EST 2004


Mine does that too. I Unplugged the ISV, the oscilations  became with less RPM peaks.
So the problem was not the ISV (i cleaned it anyway), somewhere in the loop change to fast causing unstability.
I unplugged the mudulated valve to the distributor and it stop. BUT at cold  starting i got problem: cant start, i plugged that module again , then start again..

So the problem was elsewhere. I unplugged the oxy sensor,, nothing better....
Sometime the oscilations stop and somtime the car idle so low the engine dies...

So its an unplugged procedure for now ;-). I did not investigate more than 12 min so...

Denis J

----- Original Message ----- 
From: "David" <duandcc_forums at cox.net>
To: "buck rogers" <tevalerejubeo at yahoo.com>; <quattro at audifans.com>
Sent: Friday, March 26, 2004 1:10 PM
Subject: Re: 88 90 Quattro fluctuating idle


> Sounds like a gummed up ISV. If if only happens when warm, that means the engine should be in a closed loop with the ECU & ISV controlling idle. My CGT has the same engine as your car, and I've encountered a boucing idle when warm before. I've fixed with with a thorough cleaning of the ISV. That said, it could also be a vacuum leak...
> 
> Dave
> 87.5 CGT
> SE Virginia
> ============================================================
> From: buck rogers <tevalerejubeo at yahoo.com>
> Date: 2004/03/26 Fri PM 12:45:09 EST
> To: quattro at audifans.com
> Subject: 88 90 Quattro fluctuating idle
> 
> The Idle wont stay steady after it warms up, unsure what the problem could be because most my other audi's only fluctuate when cold?
>  
> Sean 
>  
> 84 4k Quattro
> 88 90 Quattro 
> 
> 


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