info needed on over-run cutoff valve

[Deefadog]

i disconnected the throttle switch and it still would not hold the revs!

I can't test the throttle swtch at the moment as it's a right b!tch to get at! I'll have to take the intake off to get at it, i'll do this tomorrow.

I did test the over run cut off valve, and it had zero volts at idle and then registered 12.4 when I increased he revs!

when the throttle switch was disconnected I got 12.4 volts at idle on the over run cut off valve! is this any help?

[Gambit]

u can rule out the ISV module as being faulty if it still wont idle with it disconnected.

sounds like wiring is it at fault somewhere on the throttle switch or the overrun switch

[Deefadog]

I'll have to cut back all the sleeving on these switches i think and see if there is a break/short somewhere!!

Can you breiflly explain how these all work together and what they actally do, please, just so i have a small understanding of the process!

Thanks again mate, will keep you informed!

[Gambit]

when the throttle switch closes it sends a signal to the ISV control module to tell the ISV to control the idle

it also tells the bypass valve to open, so that air can travel along the pipe and into the ISV, this is then fed into the inlet manifold

when the throttle is closed. no air passes thru the throttle body at all. so u got to understand that air passes into the airflow meter, and into that pipe that branches off the airflow track to the ISV

[Deefadog]

I see! thanks.

I tested the throttle switch, and it is working fine, resistance switches when opened or closed!

from the other test on the over run, thetrottle switcht did send a voltage to it as it should right! so what is next??

I cut the sleeve back for the over run switch an diaphram as far back as i could to the bulk head, but it is really tight back there with the power steering container
right in the way!

pic -



So what's next, do you thin it's the module behind the dash? and why when it's all connected does the revs move from 1700rm to 3500rpm all on there own?

[Gambit]

if you disconnect the over run cut off, and leave just the throttle & ISV connected will it idle?

im afraid mate its just a case of playing with all three of these switches individually & in combination until you find out which one is the problem.

im near enough sure the module behind the centre console will only control the ISV and nothing else, although maybe it sends a signal to the over run cut off - im not sure

i guess the only way would be to get a hold of a spare and test it??

[Deefadog]

Yes the car idles and runs fine with the over run switch disconnected, I am loosing around 6mpg though and the revs allthough steady are slow in increasing, kind of like a steady climb no matter how much pressure is applied to the accelorator.

Do you know he correct name or part number for the module?

thnaks

[Gambit]

have a look at my post in "Parts Wanted", there is a pic of it with the part number

i dont understand how you can be loosing 6mpg though. there is no way that could cause that much of a loss

[Deefadog]

Thanks got the pic
'll post one also for that, i dread to think how much they are fromVW!


I thought that also about the mpg, but when connected on average i am getting 30-32mpg when it's disconnected i get 25-27mpg!!

[Deefadog]

I did the check on the diaphram (saucer valve, on the back of the airbox) and I dont think think it changes resistance as it should when the throttle is opened, I can't be sure as i was on my own doing it and i really need 3 hands

If this is not working do you think this is the problem?