Date: Wed, 1 Aug 2012 21:20:33 -0400
Reply-To: Dennis Haynes <d23haynes57@HOTMAIL.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Dennis Haynes <d23haynes57@HOTMAIL.COM>
Subject: Re: Idle control system
In-Reply-To: <8CF3E3598DDB907-15F8-5F29@webmail-m139.sysops.aol.com>
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Another possibility is that the AC system is overcharged causing too much
load on the engine! Does the van run well except for the idle?
Dennis
-----Original Message-----
From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf Of
Steven Sittser
Sent: Wednesday, August 01, 2012 3:47 PM
To: vanagon@GERRY.VANAGON.COM
Subject: Re: Idle control system
Dennis Haynes wrote:
> Does the engine idle near set speed with the valve electrically
> disconnected?
Yes.
> Set idles speed to at least 850 without the valves help.
It's at approximately that now.
> Even with the valve not operating the engine should be able to carry
> the AC load. Idle speed will drop but it should keep running.
In my case, the engine can't carry the A/C load unless the idle is set very
high.
> It is possible you have an engine performance issue and the idle valve
> can't compensate.
That's possible. It's not particularly smooth running, but the incompetent
shop supposedly did a thorough refurbishing of it. The engine is an AVP
rebuild from about 6 years ago. The incompetent shop claimed that AVP did a
terrible job on the rebuild, but my confidence in their opinion is not
particularly high. They're one of those "everyone's work but ours is
garbage; all parts but those we sell are garbage" places. There was a large
gap between their arrogance and their performance.
Since the idle valve doesn't adjust when it's hooked up and the engine's
running, though (it's always closed), I do have at least an idle control
system problem, separate from any engine performance issues.
Neil wrote:
> ... when you turn the steering hard right or left, the input from the
> PS switch should audibly cause the idle stabilization system to adjust
> the idle. The PS switch is easy to check.
I tested the PS switch a while back, and it's fine. (I repaired the
questionable wiring connection to it.) I didn't test the PS input at the
module (which would effectively just be testing the wiring), but since the
problem occurs with A/C as well as PS it's not an issue.
> Re: coolant temp sensor. There is a graph in Bentley showing coolant
> temps and corresponding resistance. With an infrared gun or other
> means to measure coolant temp, you should easily be able to confirm
> things.
I looked the graph, but I wasn't sure which of the two sensors (or both) it
covered, and which connects to the idle control module. According to the
graph, 250 ohms would indicate 100 Celsius, which is hotter than I expected
for a merely warm engine, but I wasn't sure if I was looking at the right
graph. To be thorough, I should check the input at a few different engine
temperatures and make sure the resistance changes in some reasonable way
> There is a fellow in Canada who sells the ISV control modules. I'm not
> suggesting "throwing parts" at the issue, but the in case you want a
> spare....
>
> http://benplace.com/parts_sale1.htm
I contacted Ben for an idle control valve (since he says he tests his used
parts thoroughly), but he's out of them. If there's a problem with the idle
control module, then I think Module Master will probably re-repair it under
warranty, or at least re-test it and verify that that's the problem.
> I noticed it's easy to have a termination push out of the block the
> idle stabilization module plugs into. Be sure the connectors are clean
> and properly seated.
I checked - putting 12V on the ST1 & ST2 connections on the idle control
module connector will cause the idle control valve piston to move, so the
connection is good.
> The throttle valve switch, as I'm learning, can be affected by a worn
> throttle body. This is mentioned in Bentley. What I experienced is
> that if the throttle is "let down" to idle slowly, the shaft can come
> to rest in one position, then, possibly move to yet another rest
> position. My *guess* is that with a really worn TB shaft, this issue
> can be worse and can make TVS adjustment tough.
Throttle body was recently replaced, so in theory this should be OK.
Thanks for the help!
- Steven
