Date: Fri, 13 Mar 2015 21:06:38 -0700
Reply-To: Craig C Forney <craig@OPUS.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Craig C Forney <craig@OPUS.COM>
Subject: Re: Idle Control System Explanation, please?
In-Reply-To: <CAHQe0n5BSnFUJs5-3u6S9oqm=4vRh8VrHRV=bW=ATbg8Hf6j-Q@mail.gmail.com>
Content-Type: text/plain; charset="UTF-8"
Kevin,
One thing to keep in mind is that when the engine is warmed up (according to the TEMP II sensor), the throttle is closed (throttle position switch closed), the AC is off (compressor clutch not engaged), and the steering wheel is straight ahead (power steering pump switch), that the idle control module should do nothing, assuming the idle speed has been set in the throttle body to around 880 RPM (as per BENTLEY).
That being said, with the engine warmed up, you can remove the idle control module, or simply disconnect the idle control valve (assuming it is a good valve and not stuck open), and the idle should be stable. If it is not stable, there is something else going on other than the idle control module. Air leaks, spark plugs, fuel injectors or fuel supply, spark plug wires, grounds, and a myriad of other things can cause an erratic idle.
Bad idle control modules behave badly by not increasing the idle when the engine is cold, or the AC is on, or the Power Steering Pump is active. Which means the engine drops below 880 RPM, and/or dies.
Really bad idle control modules behave really badly by increasing the idle when it isn't necessary, which means you will have a high idle.
Really, really bad idle control modules behave really, really badly by causing the idle to surge between normal and very high, not always consistently, which can be maddening. If they are bad enough, they can also destroy your idle control valve.
I have rebuilt hundreds of Vanagon idle control modules, and it turns out that even "known good" idle control modules often have problems lurking.
Hope this helps some.
Craig in Cupertino
> -----Original Message-----
> From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf
> Of Kevin Duvernay
> Sent: Friday, March 13, 2015 5:52 PM
> To: vanagon@GERRY.VANAGON.COM
> Subject: Idle Control System Explanation, please?
>
> Posted this on the Samba, but not getting much action there.
>
> Okay, get this:
>
> 87 2.1, all stock. Trying to diagnose some minor idle issues. Noticed my
> idle control valve wasent vibrating with ignition on, instead it was
> making a very faint whine (could really only hear it with my ear right
> next to it). So, I put a known working idle control valve in, same
> thing. Then I swapped in a known working idle control module (behind the
> right tail
> light) and boom, the idle control valve starts vibrating.
>
> However, it didn't really effect the idle of my van at all. If I had a
> bad idle control module in there that was also causing the idle control
> valve to malfunction, how could getting both working again possibly have
> little to no effect on my idle?? just looking for an explanation. Repose
> off idle does seem to have slightly improved however.
>
> For those curious, my idle issues are: idles slightly high, at or just
> above 1000. Also has a "pulsing" sound but rpms don't seem to pulse with
> it. Can only hear it from the inside. Ive got a rebuilt throttle body
> with a brand new TPS from Gowesty in the mail now, as I highly suspect I
> have a slightly worn throttle body and I know my TPS isn't perfectly
> adjusted and is incapable of being properly adjusted.
>
> Anyways, Ill save those questions till after i get the new throttle body
> and switch in, mostly curious about the module and valve effects on idle
> (or lack there of??) Is it possible that my finicky throttle switch is
> somehow not alowing the idle contol module to work as/when it should?
| 
