Thank you guies

However do you know if this valve is fail closed or fail open? Is there anything to adjust the idle manually. I think the valve is fail open and when everything is working fine, the ISCU is closing the valve on normal idle (No load) and it will send less voltage if the load is higher. If this is the case, in case of ISV failure, the idle should be high.

What do you think?

BTW I am not able to access this link : Idle stabilizer pics.

Germain ----- Original Message ----- From: RAlanen@aol.com To: vanagon@gerry.vanagon.com Cc: reglys@SYMPATICO.CA Sent: Wednesday, April 16, 2003 6:51 AM Subject: Re: Idle Stabilization Valve

In a message dated 4/16/2003 12:11:03 AM Eastern Daylight Time, LISTSERV@GERRY.VANAGON.COM writes:

My 87 Westfalia is starting well when the weather is warm. Let say above = 60F. (I'm leaving in Canada). However when it is cold, the engine is not = easy to start. The idle is very rough and I need to keep the throttle = slightly open during the warming up. I suspect the Idle Stabilizer = Control Unit (ISCU) and the Idle Stablization Valve. I had a quick look = inside the ISCU and I notice the power transistor was burned. I also = checked the Impedance of the Idle Valve and it is 0 ohm. What should be = the Impedance of this valve? If mine is 0 ohm, it could explain why the = transistor overheated. What is the failed status of this valve (open or = closed). If it is failed open, my RPM should be bigger than 1000 RPM = (right now it is 1000 RPM). If it is failed closed, I guess there is = kind of bypass to keep air flowing otherwise the motor shouldn't start.

Do you know how this valve work? The Digifant Pro training Book says, = the valve should be humming. I didn't feel anything. Is it a ON-OFF = valve or a Valve you can modulate the opening?

Germain, your deductions are absolutely correct. The ISV is defective and that is what overloaded the power transistor in the ISCU. You will need to replace them both to get your cold start problem resolved. You can try repairing the ISCU, see this link: Idle stabilizer pics, for pics of the transistor and see the following message about replacing the burnt transistor. I have tried this repair but it did not work for me. There may be other components in my ISCU that are burnt also that I am unaware of. I got a used one from a friend that I am using now. I still have two units on my desk awaiting a repair solution.

Sender: Vanagon Mailing List <vanagon@vanagon.com> From: Johan Nyberg <johan.nyberg@ABC.SE> Subject: Re: slight surge in idle speed Comments: To: vanagon@vanagon.com Content-Type: text/plain; charset="us-ascii"

Well, the little black box controlling the idle bypass valve can sometimes be repair at a cost of a dollar or two. I'm NOT saying it can always be repaired, or that the electronics are always to blame for this problem.

At the moment I have two broken controllers on my desk, they come from a neighbour's Vanagon. I don't know why his van blows them, maybe the valve is stcking and overloading the power curcuit.

I've found that replacing the BD 438 power transistor can fix this. I've been using an "upgrade", the BD 912, partly because I can't easily get the BD 438. The BD 912 has higher ratings, and should last better. One of them didn't though. It lasted one year. On my own van it has lasted for three years. Still, it is a cheap and proper fix.

Cheers

Frank Condelli Almonte, Ontario, Canada BusFusion a VW Camper camping event, Almonte, ON, June 12 ~ 15, 2003 '87 Westy & Lionel Trains Member: Vanagon List, LiMBO, IWCCC & CCVWC Vanagon/Vanagon Westfalia Service in the Ottawa Valley STEBRO/Vanagon Stainless Steel Mufflers Frank Condelli & Associates or http://frankcondelli.com