So at the weekend I started the mk2 for the first time in over 6 months. The idle was all over the place and the engine kept cutting out when the throttle was blipped. Before taking the car off the road I had setup the timing and CO, so I was pretty confident it wasn't either of these. Long story short, I traced the failure back to the Idle Stabilisation Valve (ISV). I had a spare plug and tails there that had the same plug as the ISV took so I was able to test the valve by connecting it directly to the battery. I had read that you should be able to clearly see the valve moving inside by looking in the side port. The solenoid in mine was activating but the valve wasn't moving. So I decided to strip it down. The solenoid and valve body seperate so it was pretty easy to strip it down into its main components and see what the problem was. There are four small tabs pressed into the aluminium that hold the solenoid inside the valve body housing. These can be tapped off with a flat head and hammer. When I reassembled I simply tapped new tabs down to hold it altogether again. The valve body was seized with carbon/oil/gunk build up. I gave it a good clean with carb cleaner, made sure the valve body was moving across its full length and then reassembled. Plumbed it back into the car, started it up and idle was spot on was once I adjusted the Idle Control screw in the throttle body. ISV taken apart to its main components: The solenoid end, the brass ring moves up and down to open and close the valve as required: The valve body with the valve removed. You can see the 5 tabs on outer edge of the housing that hold the solenoid in place : The valve in the open position: The valve in the closed position: And the valve head with the actuator on top:
Yes, that’s why I’ve got a selection, went through 3 purchases listed as GWO before I got one that worked
I gave this a try yesterday as I have a spare non functioning ISV. Definitely a learning experience as getting the valve away from the actuator didn't improve its appearance. Once at that stage I couldn't work out how to get the valve out of the body so resorted in the end to a good soak in petrol and lots of agitation. If the petrol was anything to go by afterwards it certainly got rid of a lot of gunk. I just need to try it in the car now to see what difference it's made as the one fitted has been very temperamental
Might try mine in the ultrasonic bath while it's pulsing to clean some Gunk out of it. Good write up, interesting to see what's inside one!.
Thank you for sharing tips ...Now i need to open mine to see inside by myself I've excat same issue with my idle and i think it the ISV messing aroud. I will buy one in remplacement
