Before you say it, I know there lots of threads about idle issues on Mk2 16v's. Ok, it's the same old thing - approach some traffic lights, press the clutch, the revs drop below idle and then rise back up to idle. Sometimes stalls, sometimes doesn't. With the help of pigbladder, I reset the idle and it made the car easier to drive but didn't solve the problem. Next step was the ISV. A few days ago I cleaned the ISV in paraffin. Soaked it overnight and then left it connected to soak for 30mins or so. Since then the idle has become even worse! I plan to buy a multimeter tomorrow to check the microswitch that activates the ISV. I noticed that working the throttle by hand, you can rest the throttle lever on the switch such that it doesn't actually press it. I can't understand why the ISV would make things worse after cleaning. It's been running for at least 50miles since the clean, so it should have settled internally. Any suggestions?
Hi Put up a picture, a birds eye view of the engine. Have you cleaned the butterfly and throttle pipes ? Have you cleaned the disc under the fuel distributor ? Have you replaced the vacuum pipes, especially the one to the brake servo ?
Starting to reckon I've screwed the ISV. Why would the idle get worse after cleaning it? I've cleaned part of the airbox side of the TB. Couldn't get it off the inlet manifold at the time but I plan to do this soon. Cleaned above the disc of the metering head too.
it wont idle properly with the idle switch not working are you double sure you haveny left a vac hose off when you cleaned the isv
There's two rubber hoses? They're all connected up, and the electrical plug is connected. Whether or not the switch is working, it wouldn't explain why the idle has got worse after cleaning the ISV?
well you know the idle switch is a problem , youve also mentioned the injectors sound past thier best ....id fix the known issues and then try to get a better idle maybe you try misting a bit of wd40 in the isv...although it goes sticky after a while so might cause more probs
Would removing the ISV and trying to dry it out overnight be worthwhile? Before my journey tonight, I wrapped a little bit of masking tape around the throttle lever so it activates the switch (I think). How do I test the switch with a multimeter? Could the temp senders be to blame? Thanks.
nah it will be dry after use haynes has the pin out for testing the idle switch...i'll get it tommorow if you want that idle switch is ajustable if you loosen the screws
Yeh, I noticed the switch was adjustable, but I was in a rush and this was a simple bodge to check it. May not have achieved anything though. I have a Haynes - will check it now.
Ok, making some progress. The microswitch does work. Tested it with my brand new multimeter. I repositioned the microswitch to make sure contact is always made - This has improved the car such that sometimes it idles straight to 950rpm, though sometimes it will drop below and then rise back up. I've had a look at the TB lever. There could be some play in it such that the TB lever won't always return to the idle position quick enough for the ISV to kick in. I wonder if a new accelerator/throttle cable will help. I'll remove the cable from the TB end and see if its nice and smooth. Any other idea's?
take the throttle body off and give it a damn good clean the other side of the TB that u havent cleaned could be full of crap making the butterfly slower....best clean it all then try it all again if its clean then its a good start
Hi There is a sort of a circlip on the cable to take up any slack at the throttle end. Do you have it.
The cable is attached to the TB lever with the clips as far as I know. The play is more in the TB lever itself I think. I would be removing it now, but its starting raining. If you mean, clean the ISV with carb cleaner, then isn't it a bit late? I used paraffin as suggested. I will clean the TB with carb cleaner. Not touched the metering head except for removing the top rubber boot and cleaning the dish and flap.
the metering head can be stripped down...some are solid with corrosion others ok. not easy as it falls apart when you split the black cast iron part down. has a little filter in there too.
Yeh, not sure the metering head is to blame to be honest. Sun is coming out so I might give the TB a go.
Ok, I still can't get one of the screws out of the TB - its the one in the most awkward place. And the head is rounding off. [:^(] I did noticed one thing. After checking the microswitch, I forgot to plug it back in. Lol. Just put it all back together and went for a drive. Seems better now I've repositioned the microswitch but I'm still not quite happy with it.
you say youve had the isv off and since then its got worse?i cant see the throttle switch been the prob but id certainly check the wires insie the isv plug boot make sre one hasnt broken off as youve disturbed it,another tip clean isvs with petrol it is a fantastic cleaner leave it over night and youl see all the carbon come out
t complivate things more the isv has a big relay in the centre console behind the cig lighter have you thort of this yet.iv never heard of one going but theres a first time for everything
