Date: Fri, 6 Jan 2017 17:19:58 -0500
Reply-To: David Beierl <dbeierl@ATTGLOBAL.NET>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: David Beierl <dbeierl@ATTGLOBAL.NET>
Subject: Re: PS Pump switch high idle question
In-Reply-To: <1080850384.556147.1483639552222@mail.yahoo.com>
Content-Type: text/plain; charset=UTF-8
Connecting the PS switch changes nothing until the switch closes; then it
applies 12V to the line. If anything, connecting the switch makes the
module more vulnerable because of the extra wire hanging off it subject to
RF influences. Certainly not less.
Correction -- since the connection is made at the switch, it doesn't even
change the amount of wire hanging off the input. So exactly zero change.
Yrs,
d
On Thu, Jan 5, 2017 at 1:05 PM, Stephen Engel <sengel543@yahoo.com> wrote:
> I wonder if an unconnected PS pressure switch would lead to failure of the
> ICM (idle control module)?
> When I was a newbie T3 ('87 Syncro hard top with 2.1WBX) owner I did not
> have access to an experienced T3 mechanic and never knew another owner,
> much less even see another in passing. So I remained ignorant of some
> aspects of its' operation. My original high pressure PS banjo fitting was a
> leaky poorly weld-repaired unit that did not have any electrical
> connections on it. After some time I finally obtained another used unit
> (there were no new or better engineered switches available at that time) it
> had the male electrical connectors on it. "Hmm, what's this? " I wondered.
> I found the the other end of the connector and joined the two ends and off
> I went.
> Previously and after the second banjo fitting I had an unsteady idle that
> eventually would surge wildly. I finally found a factory trained mechanic
> that was able to figure out the IC Valve was good along with the other
> components that input to the ICM and suggested the ICM had failed. I
> replaced it with a GoWesty rebuilt unit and my idle was fixed.
> Secondly, what are the other usual suspects that would lead to ICM failure?
> Thanks, Steve
>
> On Thursday, January 5, 2017 10:57 AM, Alistair Bell <albell@SHAW.CA>
> wrote:
>
>
> David,
>
> Right, but when the ps switch is closed....?
>
> Btw, happy Xmas :-)
>
> Ab
>
> > On Jan 5, 2017, at 3:36 AM, David Beierl <dbeierl@attglobal.net> wrote:
> >
> > The controller sends a fixed frequency pulse train to the valve, ?250?
> Hz. The valve responds to the average duty cycle and opens proportionally,
> but you can hear it hum at the fixed pitch while it's active.
> >
> > Yrs,
> > d
> >
> >> On Wed, Jan 4, 2017 at 12:12 AM, Alistair Bell <albell@shaw.ca> wrote:
> >> Ok got it. With the effect of allowing more un metered air into the
> plenum.
> >>
> >> Thanks
> >>
> >> Alistair
> >>
> >>
> >>
> >> > On Jan 3, 2017, at 8:41 PM, Dennis Haynes <d23haynes57@hotmail.com>
> wrote:
> >> >
> >> > The increase in duty cycle effectively opens the valve further.
> >> >
> >> > Dennis
> >> >
> >> >
> >> >
> >> > -----Original Message-----
> >> > From: Alistair Bell [mailto:albell@shaw.ca]
> >> > Sent: Tuesday, January 3, 2017 10:51 PM
> >> > To: Dennis Haynes <d23haynes57@hotmail.com>
> >> > Cc: vanagon@GERRY.VANAGON.COM
> >> > Subject: Re: PS Pump switch high idle question
> >> >
> >> > So it's as I guessed, the pulse cycle is biased towards more ICV
> valve open time when PS switch closes. But hold on, I misread, your saying
> the pulse bias opens the ICV further and not a bias towards on time?
> >> >
> >> > Thanks Dennis
> >> >
> >> > Alistair
> >> >
> >> >> On Jan 3, 2017, at 7:43 PM, Dennis Haynes <d23haynes57@hotmail.com>
> wrote:
> >> >>
> >> >> The PS pressure switch is an input to the idle valve controller.
> There is also an input for the AC compressor clutch. The idle controller
> looks at engine speed, temperature, and those other inputs and then
> modulates the valve to get to the desired speed. The modulation is based on
> providing a pulsed current to the valve coil. The duty cycle is increased
> to open the valve further.
> >> >>
> >> >> Dennis
> >> >>
> >> >> -----Original Message-----
> >> >> From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On
> Behalf Of Alistair Bell
> >> >> Sent: Tuesday, January 3, 2017 10:03 PM
> >> >> To: vanagon@GERRY.VANAGON.COM
> >> >> Subject: PS Pump switch high idle question
> >> >>
> >> >> Hi,
> >> >>
> >> >> Can someone school me on the way the PS pump switch affects the idle
> speed? I have a faint idea that it somehow changes the pulse to the ICV,
> I'm supposing it results in a balance that has the ICV open longer.
> >> >>
> >> >> Thanks
> >> >>
> >> >> Alistair
> >> >
> >
>
>
>
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