RE: daily update

[c a l i b a n <caliban@sharon.net>]

	this is really strange, because the behavior i observed
	today is exactly as phil describes it here.  hmmm, grounds
	for further research, for sure.

On Tue, 1 Dec 1998, Buchholz, Steven wrote:

:|> > also, noticed a new unusual behavior.  the car
:|> > seems to not want to let go of the idle speed
:|> > when i clutch in - between gears or coming to
:|> > a stop.  it takes several seconds for the revs
:|> > to drop down to idle speed once i stop.  the drop
:|> > is a slow, smooth decline.  i am going to check
:|> > the throttle linkage stuff, but i thought there
:|> > might be a good btdt from y'all.
:|> 
:|> You fixed something.  This is what it's supposed to do - or at least,
:|> it's what the ur-quattro ISV controller is supposed to do, and I think
:|> it's the same part.
:|> 
:|> Idle is 800 rpm at rest - optimised for low vibration.  It's raised if
:|> the battery voltage is low or the a/c is on.  The ISV will _not_ allow
:|> idle to drop below 2000 rpm if the vehicle is moving - it assumes you
:|> might need the power steering or the brake accumulator refreshing.
:|> 
:|> If you knock an ur-quattro MB (equivalent to the MC engine) out of gear
:|> and coast gently to a stop, the idle drops in specific stages and
:|> finally drops to 800 rpm some seconds after the car comes to a halt.
:|> 
:|... for better or worse, Rocky lives here in the good ol' USofA ... which
:|means that unless his car was modified by a P.O. it is equipped with the WX
:|motor ... which might map somewhat to the WR with which you may be familiar
:|... the only sort of idle speed control that the WX motor has is a timing
:|advance that the ECU kicks in if the idle speed drops too low.  Cold engine
:|throttle plate bypass is controlled by an Auxiliary Air Regulator (AAR)
:|valve ... it has no ISV.  
:|
:|I think that Rocky has pretty much nailed the possibilities ... something
:|may be sticking in the throttle linkage (don't discount the cruise control
:|actuator).  Newer turbos such as the later MC engines had a dashpot on the
:|throttle body which prevents the throttle plate from closing abruptly, but
:|the WX doesn't have this mechanism either.  In trying to think about other
:|oddball faults that might cause the idle to drop slowly ... perhaps the high
:|vacuum condition in the intake manifold is causing one of the throttle valve
:|bypass valves (AAR, valve that provides bypass when the A/C is on, etc) to
:|be drawn open and bypassing the throttle body ...
:|
:|HTH!
:|Steve Buchholz
:|San Jose, CA (USA)
:|


--
 rocky mullin
 http://caliban.sf.ca.us/
 two strokes are faster than four!
 this message was composed using the vi editor.
 '83 ur-q - yamaha rz350 - suzuki ts250 -  chaotic good