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Tue May 19, 2009 10:16 am

Hello,
So I'm slowly going through my new-to-me '88 Vanagon Wolfsburg, and my most vexing problem at the moment is a really poor idle and drivebility when the Van is cold (and, it takes a long for it to warm up too). I have little power in the low RPMs and it stutters and bucks until finally the Van is warm. The last few warm days in California have helped to speed things up.

So while I've changed the fuel filter, cleaned the fuel pump, put new plugs, new plug wires, distro cap and rotor, new air filter and even a F.I. cleaner through the system, I'm still with my old cold sputtering morning problem.

But my real question here is this: while going over the F.I. system, and testing/cleaning, resealing parts, I get to the Idle Stabilizer Unit, and I see this:

It is the white wire with green stripe that is cut. I'm thinking: this isn't right...any suggestions about what this might cause my Van to do or not do? Should I splice it back together?

Thanks in advance,
Steve[/img]

Tue May 19, 2009 10:54 am

splice it back together and watch all your problems go away.

Tue May 19, 2009 11:03 am

Yes, that sounds good to me...but do you also know the why of it? I'm kinda just curious as to why the previous owner might have cut it in the first place?

Tue May 19, 2009 11:06 am

Well it may be the RPM signal. That essentially takes the Idle Computer out of the loop. But trace it out on this eaiser to read schematic:

Download the following:
86 Vanagon Protraining.pdf
Vanagon Protraining Digifant I 86-91.pdf
Vanagon Protraining 86-91 Fuel Systems.pdf

So if you want a better schematic get it from my public folder:
Vanagon Wiring Diagram.pdf

http://homepage.mac.com/WebObjects/FileSharing.woa...mp;lang=en

Tue May 19, 2009 11:10 am

Hey, that's great. Thanks Dogpilot. I'm on the task!

Tue May 19, 2009 12:39 pm

The wire color is for the signal wire from the A/C compressor clutch. It tells the idle unit that the A/C is running so it knows to speed things up a little. Should do nothing unless A/C is turned on and functional.

You can find the other end of that wire over by the coil, and check with ohm meter to verify that is the one it is.

Mark

srb wrote: Yes, that sounds good to me...but do you also know the why of it? I'm kinda just curious as to why the previous owner might have cut it in the first place?

Tue May 19, 2009 7:27 pm

I checked out Dogpilots PDF on the Vanagon wiring, and the White-Green wire is listed as "NOT USED." Huh? So I'm going to hunt down where it does lead to and see what's up.

Tue May 19, 2009 8:47 pm

As I said before, it will be for the A/C status signal and only connected if that option was on the van. The various wiring diagrams, even the offical VW ones, overlook this connection at least slightly. The Bentley A/C wiring diagram shows a wire leading to the idle control unit from the compressor but doesn't say exactly which pin or wire color for the FI harness junction.

A related question has been asked countless times in many forums. People look in their engine compartment and see a loose white/green wire dangling near the ignition coil. Then they wonder where it is supposed to be connected. The answer is, if no A/C, no connection.

Mark

srb wrote: I checked out Dogpilots PDF on the Vanagon wiring, and the White-Green wire is listed as "NOT USED." Huh? So I'm going to hunt down where it does lead to and see what's up.

Wed May 20, 2009 2:42 pm

I have AC, but it is disconnected in the interior cabin, because the plastic housing broke off in the past. So, the AC motor is still turning on the belts, but never in use. And truly, the Idle Stabilizer doesn't need to know this at all? I find it odd that cutting the wire somehow helped the system out one day in the past.