Isv or not isv,that is the question?

[Loynes]

My idle is bonkers its at 3000rpm,  I think it might be the isv up the creek.  when I unplug it, it dies, when I squeeze the vacuum hose that goes to the air box is goes down to the right place. When I unplug the vacuum hose completely it dies as well.  I know it been covered but the treads never have a completion or a solution.  Any ideas

[mk2addict]

I'd say it was the isv, just sold one that was working on my abf and swap it for one that doesn't and its doin the same as ures

[clipperjay]

You can test it for resistance on the ISV test for 2-10 Ohms
The idea of pinching and blocking the air flow is to starve it off boost hence it will die if it makes no difference like a drop in idle speed it must be sucking air flow from somewhere else i.e air leak?
Does it buzz when you turn on ignition?

[mk2addict]

Don't they flucturate and peak on idle if it was an air leak

[clipperjay]

Don't they flucturate and peak on idle if it was an air leak

Depnds if the jack stop piston is stuck open so it can run in a emergency.

[mk2addict]

What's a jack stop pin?

[clipperjay]

[Loynes]

The revs were going up and down before this started,  then it happened and went away then its here to stay. Interestingly this only happened after a stretch of full throttle dual carriageway use, I wonder if the jacking piston was sucked open and has got stuck?  Next thing aim going to do is remove the inlet manifold and re fit with new gaskets just in case there is a air leak.

[Loynes]

Just thought I'd I would update this problem,  cleaned the isv made no difference.  So decided to check for leaks,  came up with idea to spray the inlet manifold with carb cleaner,  which if there was a leak it would change the revs ie the higher octane carb cleaner would make the car rev higher.  Bingo this worked it was drawing air through front of the inlet manifold on the joint with the spark plug rail.  Refitted with a little instant gasket and the revs are steady as a rock.  Still feels a bit flat but the mixture is certainly out because of the leak.

[clipperjay]

I would drop the manifold order new gaskets before then use proper red gasket sealent before bolting it up.
A lot of these issues with 16vers are air leaks and its always hard to find them until you either use start spray or carb cleaner to establish whats going on, but I'm guessing you have read so much and now have a better understanding of how the engine and TB works it all makes sense a simple air leak can cause so much grief right 
Glad you solved it by yourself