VR6 engine Reving on its own!!

The other night I was driving my 92 VR6 through Wandsworth, and gave it a bit of stick. Then I stopped at the lights and the revs sat at 2000 then dipped to 1500 for a few seconds and then back up to 2000!
This went on for a while and i drove the car home. Just before I got home I revved it hard it 2nd gear and it seems to clear the fault. But I know it will come back as I have has it before.

Any Ideas?

Thanks

JAcko

 

Coolant temp sensor?

 

clean the ISV if pre'96 car.

 

Where is the ISV on a VR??

 

ok, cool I will try and clean the ISV with some carb cleaner and check the electrical connections.
So where is the ISV and what does it look like?

 

Atlas, its to the right of the throttle body as you look from the front of the car.

 

the silver thing in this pic is the ISV...



just to reiterate, its only on obd1 cars (upto M plate). it is under the plastic plug lead holder at the back of the engine.

take it off and spray carb cleaner all into it.

is also worth cleaning the throttle body as well.

out of interest though, does anyone know how much a new ISV costs?

 

(an arm and a leg)

 

Mine is an OBDII and the ISV is in exactly that place

 

OBD2's don't have ISV's! so yours is an OBD1 then.

what year is yours?

 

Thanks for the pic, so now i know what the ISV is, but whats the black boot thing on the bottom left of the pic. Mine has a "tywrap" around it. So somebody must have taken it apart. I dunno why?

 

the boot thing is what holds it onto the throttle cable holder thingy, and also holds a few wires out the the way.

 

Yes they do!
It is a 1995 M reg, and it definately has an OBDII port.

 

its deffo an obd1, m plates are obd1.

you're getting confused, the later obd1's and the obd2's have the same port, its only the very early obd1's that have the different two plug port.

 

Ah i see now

 

vw do like to confuse people i think

 

I had a look in the Bentley manual, i didn't notice the OBDII was missing the idle stabilising valve before.
Ah well we all have something to learn
Edited by: vwpolo2000

 

They have a different inlet manifold as well due to the redesigning of the throttle body

 

As I found out to my expense!