Further idle troubleshooting

[jAndrew]

[Vanagon Nut]

Ok, good.

Well, maybe someone more knowledgable than me can comment but to me, it sure seems like something in the idle control system has a fault.

But assuming the duty cycle test shows that the current draw is out of spec, afaik, that doesn't really point to one specific part.

The ICU can be opened up. Sometimes, a failure of a component on that unit is obvious.

I found that mine was held pretty tight to the socket so take your time removing it; the contacts in the socket are a specific design that really grips the male contacts.

In terms of taking it apart, what I'd do is use a thin semi wide plastic tool to separate the case from brown board part. Just work your way around. Once you have the case loose, the printed circuit boards should slide out.

Neil.

ICU socket

_________________
1981 Westy DIY 15º ABA

1988 West DIY 50º ABA

VE7TBN

[jAndrew]

[Vanagon Nut]

You're welcome Andrew.

My money is on a bad ICU. That said...

I'm sure this was mentioned but if your Syncro has power steering, if the "hot" PS switch wire has shorted to ground for any length of time, that could've damaged wires which *might* include wires to/from ICU socket.

Neil.
_________________
1981 Westy DIY 15º ABA

1988 West DIY 50º ABA

VE7TBN

[jAndrew]

[jAndrew]

From another post by Gauche1968:

"Assuming the OP has Digijet, he has a different component. The Digital Idle Stabilizers' job on Digijet is to constantly alter timing at idle on the fly to keep idle from falling below 800 RPM. Typical failure mode is the van wont run at all, because the ignition signal is not getting through the failed component. You test for this by unplugging both connections and snapping them together. If the van starts and runs the idle stabilizer was bad (Of course, there could have also been a wiring problem that unplugging and plugging back in temporarily cured)."

I will play around with the ICU a while later.
_________________
'89 Syncro Doka

[Vanagon Nut]

Ahhh, right, ok.

I now see J 87 DIS unit in the 2.1 Digijet diagram at "engine compartment left" as well as an N 41 TCI also at "engine compartment left". However, the same set of diagrams do show an idle speed stabilization unit at "engine compartment right".

Apologies if I kept your focus on the wrong part!

Neil.

[bajabones]

I have the same rig & motor
I went through all tests & troubleshooting
Changed all the parts
The things that fixed it were
The fuel filter & intake manifold gasket’s & boots and the special NGK plugs
Runs perfect
_________________
1990 Syncro Doka
2.1 DJ
Triple Knob
Solid shaft

[slo356]

This wandering idle issue is so common with so many different solutions, I would like to see a poll on what-solved-what? How many people found timing? How many found the ICU? How many found vacuum leaks? Where?...etc. Of course there are a great deal of variables here but I think a poll could be worded in a way that would capture at least solution trends.

A poll could then be converted into an organized mathematical flow chart which might lead to quicker solutions for many.

Maybe share poll results with vendors which "could" help with stocking necessary parts.

There is a great deal of accumulated real world experience here in the Forum and capturing it and then converting results to data would be a useful effort.
_________________
'65 T1 Sedan
'87 T3 Syncro

[djkeev]

[Vanagon Nut]

From my non expert level point of view, comparing 1985 1.9 Digijet in Bentley vs 2.1 Digijet diagrams, though there's differences in wire colours, the wire assignments of 2.1 Digijet N41 J87 and 1985 Digijet 'transistor ignition control unit' and hall gen, *appear* to be the same.

I have only found the wiring diagrams for 2.1 Digijet so don't know if the Pro Training manual shows this but were it me, since it seems the ISV or ICU may have a fault, I'd fully disable the ISV ICU system then test N41 J87 parts and maybe check engine timing. i.e. an known good engine w/o PS and/or AC should idle and run fine without the ISV ICU system.

Neil.