1990 VW Vanagon ignition problem


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Old 05-04-07, 01:19 PM
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1990 VW Vanagon ignition problem

My 1990 Vanagon runs very rough in idle when it's damp out... after a rain...
to the point I can barely keep it running at a stop light or it just stalls completely. Never when running, though. When things dry up she's just fine.

Have had the ignition wires replaced twice, new cap and all with no luck. The local service center (not VW) has checked everything and tells me there is a
computer in this old girl that may be the issue.

My hunch is it is an issue with electrical contacts somewhere as this would seem to make the most sense. Can anyone tell me where this "computer"
is in the van so I can take a look-see at the terminals, connections, etc..

Any other thoughts will be greatly appreciated. Most of the fellows who used to fix these older vans are long gone or have moved on so I really have no one to call upon when it is a "VW specific" problem.
 
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Old 05-05-07, 03:19 AM
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Cool 1990 VW ignition

Only when wet? I have no idea where that computer is but do you suspect the spark plug wires when wet? Have you considered spraying the wires with some kind of protective silicon? Can you see any arcing when this happens?
 

Last edited by NewHomeowner396; 05-05-07 at 03:19 AM. Reason: mispell
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Old 05-05-07, 08:33 AM
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It's not the spark plug wires. These are new two times over.
 
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Old 05-06-07, 09:52 PM
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wet or damp?

Does it run poorly after first start after sitting overnight in the rain or does it run poorly after running on a lot of wet streets and through puddles?

I think most of your ignition stuff is on the left side of the engine compartment. Donít suspect the computer. Look for loose connections and tape anything that looks like it will allow moisture to enter. The thin wire to the coil is an example, but you would have problems beyond idle if that was the problem. All your watertight connectors are getting old and may be leaking. It sounds like something is drying out as the engine compartment warms up, if I understand your post.

I had a Ď84 that did not have computer controlled ignition only computer controlled injection. Later models like yours had computer control of both. On the í84 the throttle had two exterior mounted micro switches (no throttle position switch) these signal fully closed and fully open throttle and the computer in both cases ignores the air flow meter input. If you have these look for loose or wet connections at closed idle switch. If this switch does not work the idle is terrible.

If you donít have this switch, look at the top of the air flow meter. I have never seen one that has not been pried open. If the top is loose clean the contacts with electrical parts cleaner but donít touch them and reseal the top with silicon.

Are the plug wires the original style? The end that goes on the plug is rather long and has a metal shield around it.

How is your battery and charging system at low rpm? Wet?

Automatic or manual tranny?

Write back with progress/answerers.
 
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Old 05-07-07, 06:59 AM
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Thanks Peabees, for the detailed reply.

After a night of rain I will almost always have trouble. Humid/damp summer days also, sometimes. I can go for miles on the highway, get off at an exit, stop at a light and it just dies. Always restarts no problem and then if I tap the gas three or four times it will idle fine.

That's why I was thinking "computer". Like it needed to be reset or reboot so to speak and the tapping of the gas did the trick. I'm a layman as you can tell but the tapping trick seems to work again and again.

I've tried adding gas treatment, carb treatment, ...Lucas brand.

Where are these micro switches to be found exactly?

Also, the flow meter. What does it look like and where can I find it.

BTW: I have an automatic transmission.
 
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Old 05-07-07, 07:47 AM
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air flow

The airflow meter is downstream of the air filter, which is between the air filter and throttle. Have someone operate the gas pedal and see what moves in the engine compartment, the part connected to the cable is the throttle. Does it have the switch(es) I first wrote about? The airflow meter has a flap that opens as the air volume increase and has a square plastic top on the electronics.

Your last post is really pointing me to the idle switch not always closing until you tap the gas a couple times. Confirm if you have it. It will be on the throttle w/ wires coming from it.

On wet mornings before driving, you start it up and get fast idle because it is cold correct? As it warms, the idle should slow down. Does it slow down and die or only begin that behavior after you start driving? I asked about the tranny, because I wondered about linkage to the engine and maybe TC lock-up, but I am starting to get in over my head w/ an automatic.
 
 

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