88 90 Quattro fluctuating idle

[Denis]

  I did verified the idle switch. Was working good.
  Ðenis

  ----- Original Message ----- 
  From: "Huw Powell" <audi at humanspeakers.com>
  To: "Denis Julien" <sparkplugvw at hotmail.com>
  Cc: <quattro at audifans.com>
  Sent: Saturday, March 27, 2004 8:19 PM
  Subject: Re: 88 90 Quattro fluctuating idle


  >
  > > 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 suspect teh idle switch.  If it's not closing, the ECU does not know
  > to regulate the idle with the ISV.
  >
  > > 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..
  >
  > Yeah, well, that would happen.  That "valve" is how the ECU enriches the
  > engine for cold starts...
  >
  > >> 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. ... That said, it could also be a vacuum
  > >> leak...
  >
  > -- 
  > Huw Powell
  >
  > http://www.humanspeakers.com/audi
  >
  > http://www.humanthoughts.org/
  >