Troubleshooting Idle Control Valve (high idle)

[16CVs]

Checked my ICV , no vibrate . Into my parts stash and out came another ICV . Plugged it in and Walla ,perfect idle .
That was a frustrating repair . But I now know a lot more than when I started this repair .
I also pulled my Temp II sensor which was reading bad and replaced it with a known good unit as well . I then bench tested the old one and it seems to be with in spec ? Of to find a German Temp II sensor for my spares .
Oh well it runs great and maybe my mileage will increase .

Stacy
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1989 Syncro Tristar Triple knob "Swedish"
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[beachinwesty]

This is a very interesting thread. But here is my question. Does all of this discussion relate only the the 2.1l or does it apply to the 1.9l as well?

Beachinwesty

85 Weekender

[Mathew Zelezen]

Well it certainly vibrates with ignition on and when running..

Thanks for the heads up on Ben for used ISCU's Navy_Flyer.
He's currently out of the D style but I'll keep looking.
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87 Syncro Tintop
~Rocky J Motor
~Steedle Trans


Of all sad words of tongue or pen, the saddest are these: It might have been.

[Mathew Zelezen]

Well its not the Idle Speed Control Unit..

I found another working unit and replaced it but I'm getting the same results. The idle stays at 2000/2500 and doesn't go down when warmed up. (When all this first started in the fall it would drop back down to 850 after a minute of driving but now its pegged.)

So I did some diagnostics to see what the ISCU was receiving:

1. I have continuity between the RPM (middle wire)on the diz and the terminal on the ISCU plug.

2. I adjusted my idle with the big screw to 800 with the RPM signal wire on the firewall disconnected.

3. Checked continuity between the Power Steering and TPS wires and ISCU plug.

4. And made sure my TPS was sending a signal when operating.


The Idle Speed Valve snaps closed when I pull the plug with the engine running and it drops down to 800 so I know its not staying open on its own..

I tried following some of the other wires from the ISCU but I don't know what it means on the schematic when the wire ends at a number in a box (pg 97.90) Where does the Temp 2 come in to play?


I'm running out of ideas here..
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87 Syncro Tintop
~Rocky J Motor
~Steedle Trans


Of all sad words of tongue or pen, the saddest are these: It might have been.

[Mathew Zelezen]

Any takers?..
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87 Syncro Tintop
~Rocky J Motor
~Steedle Trans


Of all sad words of tongue or pen, the saddest are these: It might have been.

[T3 Pilot]

The number in the box is a reference to the current track to follow the wire. You may have to flip back a few pages to find it. In the case of the green yellow wire for temp 2, it is connected to both the ECU and the Idle speed control unit. This connection is in current track 41 at the ISCU (Bentley 97.125) and current track 25 at the ECU. (Bentley 97.123) I am referencing the pages for my Vans year, yours will be similar.

The number in the box is a pointer that makes the printed version of the wiring diagram work in the confines of the manual. I would like to know how to make a 3D version of a wiring diagram on my computer. Maybe there is an app for that? Colour version for the individual wires? When I am messing around with a specific wiring problem, I print out the associated pages, then assemble them in order and mark them up in colour, scribble notes on the pages etc.......

So anyway, chase down that G/Y wire and check it for damage and ensure good contacts. T 2 sensor can be tested with your VOM for reassurance that it is not part of the problem

Good Luck.
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1988 Vanagon

The most important part in every vehicle is the nut behind the wheel......

[Mathew Zelezen]

Thanks for the heads up Syncro Pilot. I'll check it out in the daylight tomorrow and make sure I have continuity between the ECU and ISCU.

Great idea for the 3D wiring model. I just took an Anatomy & Physiology 2 class and I found some really helpful 3D models on the circulatory system that some one made using one of Google's applications. I'll look for it an report back if I find it.
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87 Syncro Tintop
~Rocky J Motor
~Steedle Trans


Of all sad words of tongue or pen, the saddest are these: It might have been.

[Mathew Zelezen]

Well unfortunatly I have great continuity between the ECU and the ISCU.. meaning I still don't know why my idle is so high.

I re-checked the timing and was attempting to reset the idle when I noticed that if I disconnected the RPM signal wire on the back firewall it didn't affect my high idle.

I was under the impression that this was how you stopped communication between the ISCU and the ISV when setting the timing. Am I wrong or this an indicator of something else askew or perhaps a sign of what may be wrong?

Just grasping at straws here..
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87 Syncro Tintop
~Rocky J Motor
~Steedle Trans


Of all sad words of tongue or pen, the saddest are these: It might have been.

[tencentlife]

I mentioned somewhere else here recently that everything can check out in the wiring, the ISCV can be clean and humming happily away, but that doesn't mean that that ISCU can respond to increase in load at idle and compensate by increasing the PWM duty cycle. One way to be sure is to tune idle speed to the base duty cycle as is described in Bentley, rather than by ear as we mostly do since it's such a pain to do it the "proper" way.

I have checked a bunch of ISCU's that run the valve only at base duty cycle but don't accomplish the increase, from my experience this would be the dominant "failure" mode.
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[Mathew Zelezen]

Thanks tencent for the feedback.

I have followed similar posts that you've replied to saying that these units are prone to fail and typically in this manner..(or in your case just shelve them for awhile and voila they work again).. and in the few cases where the OP responds on what the problem was its usually to report that it was a failed ISCU.

This is my second ISCU in attempting to fix this problem and I'm getting the exact same symptoms. So I'm leaning towards "centering the ISV" as Dog is fond of saying. Not to say that I haven't received broken "new" parts before but the chances of this other ISCU being faulty the exact same way is slim.

Don't own anything to check milliamps with but I'll see what I can find at Radio Shack and report back.
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87 Syncro Tintop
~Rocky J Motor
~Steedle Trans


Of all sad words of tongue or pen, the saddest are these: It might have been.

[Mathew Zelezen]

Centered the ISV and that wasn't it.

I went to my local shop this afternoon and promised I'd get his kids first in line at their next ER visit if I could use his spare ICV to test and see if mine was bad.. and low and behold its the valve. I hate throwing parts at an engine and its been a mission but I sure learned a lot in the process.

My final question is will an Idle Stabilizer Valve from Euro's work on the Vanagons?
Found one with the model number 037906457 C

Thanks!
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87 Syncro Tintop
~Rocky J Motor
~Steedle Trans


Of all sad words of tongue or pen, the saddest are these: It might have been.

[Navy_Flyer]

[Mathew Zelezen]

Thanks for the heads up Navy Flyer.

I agree that there are more than a few available in the Classifieds but some look like they were resurrected with the Titanic, so I wanted to get the latest model available with the most life left in it.
_________________
87 Syncro Tintop
~Rocky J Motor
~Steedle Trans


Of all sad words of tongue or pen, the saddest are these: It might have been.

[Garske]

I had the exact same issue as the original poster in this thread and this post really helped me get to the solution, I thought I would add a few notes…

The issue - If I disconnect the ICV it idles very nicely at 800 rpm.. but when its connected it idles at 2000 rpm so I'm confident this is my source. I can squeeze shut the line and the idle drops back to 800 again so I think the ISCU is sending an erroneous signal to the ICV to stay open.. but I don't know why.

What I did - Did all of the same checks as above including looking for vacuum leaks, etc. I originally thought the issue was the Idle speed control unit because I was getting a voltage reading just outside of the expectable range in the Bentley. And when I turned the key in the ignition the ICV buzzed.

The solve – The new control unit seemed to make things even worse, so I pulled the ICV. The valve in the ICV was pretty gummed up, but even after cleaning it with carb cleaner and a small screw driver I could still blow air through the valve. I picked up a used ICV which solved the issues.

Lesson learned – Even if the ICV buzzes, it still might be the issue. Spraying carb cleaner in the ICV might help, I tried that several times, but it only helped a little. I could have saved myself a lot of time if I had just pulled the ICV off of the engine in the beginning to getter a closer look. If the valve looks closed but you can blow air through one of the ends your ICV is the problem.

[rbernard25]

my 86 2.1 has been idling high around 2000 rpms. I have replaced the ECU, Idle Control Valve and Idle Stabilizer. It ran fine for two days and then died today. The rpms were around 2000.

The throttle switch bit the dust a month ago and I replaced it with the Go westy plug n play TPS. It docent have the allen heads on the top to adjust the idle, but has a movable baseplate where you can set the idle to get both audible clicks at idle and full throttle. After I replaced the TPS it fired right up but with the high RpMs.

So I decided to replace the ICV and Idle Stabilizer. I hoped this would bring the rpms down- nope, it ran high again and now will not start. I tried two different ECUs, no start. Pulled the TB off and adjusted the base plate, nothing.

The guy I bought the bus from had unplugged the ICV and told me the plug had a short. I fixed the plug. Funny thing, I drove for a year without the ICV plugged in and it idled fine until my ECU died.
So now I'm just confused.....what's next? Help appreciated.
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86 Westy


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[erikgundy98]

This post has be perplexed. I am working on my 90 Muiltivan, standard 2.1 waterboxer engine with no modifications, but has the same idle problem. My idle problem is a little different though. Starts fine, idles perfect for about 5-15 seconds, then slowly climbs to 1500 rpm, then goes from 1500- 2500 within about a minute.

I had a helper turn the key over, and although I did not hear the ICV buzzing, with my ear to it, I heard it trying to do something. So I cleaned it out (was not able to blow through), and tried starting without it hooked up. Bus wouldnt start or hold idle without the ICV hooked up. With hooked up, it did the same thing as above.

Since bus wont start without ICV, does this mean it might be good? No buzzing though. But it is a 1990. Thoughts?
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'90 Multivan Westfalia

[erikgundy98]

Where is the temp 2 sensor you guys refer to in these posts? Not the sensor in the coolant Reservior ...
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'90 Multivan Westfalia

[T3 Pilot]

Here is a clear image of the component in question....

https://shufti.wordpress.com/2013/07/25/vanagon-temp-ii-sensor-replacement/

I recommend ordering a spare and testing it prior to installation. Matter of fact you can test the one installed in your van with a dvom and a thermometer to see if it is close to spec. Ref. Protraining manual page 17 or Bentley not sure which page. Let us know the results....

Good luck.

Edit: the image shows a threaded temp 2 sensor, yours will be a clip in type. Same location for each
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1988 Vanagon

The most important part in every vehicle is the nut behind the wheel......

[OldBlueSyncro]

So I'm having an idle problem too. When I turn on the key, my ICV pops open but doesnt vibrate. Is this right? Sounds like it should be vibrating.

[yvessergerie]