Date: Fri, 12 Sep 2003 11:00:03 -0600
Reply-To: Chad Morris <chad@ALLMORRIS.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Chad Morris <chad@ALLMORRIS.COM>
Subject: Re: idle stabilizer: valve, control unit or both?
Content-Type: text/plain; charset="iso-8859-1"
This may seem like a stupid question, but why do I even need the ISCV/ISCU?
Is is just for cold starts or is it supposed to do something else? I have
been running around with it unplugged for the past couple of days and my
engine is running better than it has for ages. No high idle, no
surging/hunting. Someone please help me understand this.
----- Original Message -----
From: "Wolfgang Ziegler" <ziegler@princeton.oilfield.slb.com>
To: "Chad Morris" <chad@allmorris.com>; <vanagon@GERRY.VANAGON.COM>
Sent: Thursday, September 11, 2003 8:45 AM
Subject: Re: idle stabilizer: valve, control unit or both?
> Chad,
>
> At 12:10 AM 9/11/2003, Chad Morris wrote:
> >I did not realize the Idle Stabalizer Control Unit could be taken apart
and
> >be re-soldered. I will look into that. Is it hard to get apart?
>
> on my unit there are small plastic tabs, you can carefully bend the
housing on one side outward and slide in a thin blade (razor blade), then do
the other side. The unit should then slide out. You can easily see the large
solder joints on the back of the board. For assembly, it will snap in place.
>
>
> >Also, when you mention the poor contact to the ECU were you referring to
the
> >Idle Stabilizer Control Unit, or did you mean the main Control Unit that
> >lives under the rear passenger seat?
>
> main control unit - I had a leaky rear core and it was pretty wet for a
long time under the seat. I could see some discoloration and even 'blooming'
(sorry for the non-tech explanation) on the contacts on the ECU. Cleaning
and changing the spring tension in the air mass sensor got it out of the
resonance.
>
> But caution, if you don't carefully document what you change in the AMS it
will be difficult to get back to where you started from...
>
> Wolfgang
>
>
>
> >----- Original Message -----
> >From: "Wolfgang Ziegler" <ziegler@PRINCETON.OILFIELD.SLB.COM>
> >To: <vanagon@GERRY.VANAGON.COM>
> >Sent: Wednesday, September 10, 2003 9:30 PM
> >Subject: Re: idle stabilizer: valve, control unit or both?
> >
> >
> >> Germain, Chad,
> >>
> >> there are probably many causes for this idel instability. Here two of
my
> >> recent encounters:
> >>
> >> a) Engine races after startup, then cuts off - would not have enough
power
> >> to drive:
> >> Long trouble shooting & frustration, finally turned out to be
connectors
> >on
> >> the idle control unit which had broken solder joints on the board: a
> >couple
> >> of the large metal spades cracked the solder and had intermittant/no
> >> contact (a failure we see frequently in heat cycled electronics):
> >re-solder
> >> and all was fine
> >>
> >> b) Oscillating RPM (600...1200)
> >> A combination of poor contact to the ECU (the connections were
corroded)
> >> and a worn air mass sensor (change spring tension by one notch)
> >>
> >> Just some hints, solder or change AMS parameters at own risk... :)
> >>
> >> Wolfgang
> >>
> >>
> >> At 08:37 PM 9/10/03, Germain wrote:
> >> >Hi Chad
> >> >
> >> >It could be both, it is hard to say. Many mechanic guies change both
> >units.
> >> >They are expensive devices. This is why I am trying to fix it.
> >> >
> >> >The ISV should read continuity on a multimeter.
> >> >
> >> >I am still experimenting on those devices. Here is what I have done so
> >far.
> >> >My idle valve (ISV) seems to work OK when I put 12 VDC on it. No
power,
> >the
> >> >valve is thight closed, with power, the valve open (No humming because
> >the
> >> >ISCU is the solid state unit which can modulate the valve). After
> >changing
> >> >some composants in the ISCU, I put 12 Vdc on it with the ISV connected
to
> >it
> >> >and the ISV was humming. After that I put back all the devices on my
> >engine,
> >> >and I turned on the ignition key (without starting the motor) I could
> >feel
> >> >the ISV humming with my hand. After 10 or 15 seconds, the ISV stopped
> >> >humming. I decided to start the engine and it started very fine,
better
> >than
> >> >when the ISV was disconnected but after a while the engine started to
> >surge.
> >> >When i disconnected the ISV, the engine was idling fine.
> >> >
> >> >I have checked the gas throttle switch and it seems to be OK. Next
step,
> >I
> >> >am going to clean the ISV with a brake cleaner.
> >> >
> >> >Germain
> >> >
> >> >----- Original Message -----
> >> >From: "Chad Morris" <chad@ALLMORRIS.COM>
> >> >To: <vanagon@GERRY.VANAGON.COM>
> >> >Sent: Wednesday, September 10, 2003 7:08 PM
> >> >Subject: idle stabilizer: valve, control unit or both?
> >> >
> >> >
> >> >I am experiencing the ever so common high idle problem on my '89
Carat.
> >> >Don't hear the infamous hum or buzzing sound coming from the idle
> >stabilizer
> >> >control valve (how loud is that supposed to be, anyway?), but if I
> >> >disconnect the wiring harness going to the valve while the engine is
> >> >running, the idle immediately settles right down to 850 RPM. If I put
> >the
> >> >plug back in, the idle speed stays at 850 RPM, no change. Does this
> >> >indicate a bad valve, control unit, or both?
> >> >
> >> >Aside from replacing with "known good parts", of which I have none at
my
> >> >disposal, are there tests I can perform with a multimeter to determine
> >> >functionality? Can I apply current directly to the valve with the
engine
> >> >off to see if I hear the buzzing?
> >> >
> >> >Chad Morris
> >> >'89 Carat
> >> >Salt Lake City
> >>
>
>
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