90' Passat Aux air valve probs

**ausgolfer** · 27-08-2006, 10:32 AM

How do I check the function of my auxilary air valve? I though this was the problem as the car won't start well or idle when cold. I got a different valve and it hasn't fixed the problem. Some people told me the valve must buzz when you switch the ignition on which the original one didn't do and the newer(2nd hand) one didn't either?
Can I just check it with a multi meter or connect it up to a little 9v Bat to check it?

Any suggestions would be great. Carl.

**h100vw** · 27-08-2006, 10:40 AM

Make sure the throttle closed switch is working. That's what makes the ISV operate I believe. Exactly which engine do you have? 2E 2 litre or something else.
There is an output transistor in the ECU that has been known to blow and stop controlling the ISV.

GAvin

**ausgolfer** · 27-08-2006, 11:42 AM

It's got a 9a engine, it could be that switch you're talking about.

**h100vw** · 27-08-2006, 11:50 AM

I had a 9A, all kinds of trouble with the tickover. The switch is the culprit.

I have the Bentley for that car too in case there is any probs with diagrams etc.

Gavin

**ausgolfer** · 27-08-2006, 12:24 PM

so how do I fix the switch? or do I need a new one? or worse still a new throttle body?

**h100vw** · 27-08-2006, 06:20 PM

Switches available seperate to the TB. The switch itself is a common or garden microswitch which I bet you could get from Jaycar or Tandy. Just need to make sure the throttle is closing properly, ie the cable isn't too tight.

Sometimes the connection to the ECU loom gets oxidised up and a good re-rack of the connection with some contact oil fixes it.
GAvin