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S2 Idling Fault

944psi

944psi

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What should I check if the rpm hunts around when idling? With a warm engine, it returns to idle speed. If the accelerator is blipped say to 2k rpm it then returns to about 4-500 rpm and then to 1200rpm and continues until the accelerator is pressed again.

Is there an idle stabliser that can be checked or is it likely to be something else in the air/fuel system? I read in the manual that any problems with idling could be diagnosed with the plug-in diagnostic box. Would an independant have one of these or would it be an OPC job?

Phil

89 944 S2 Guards Red, black leather, black (rusty) sills, owner still smiling tho.
 
Clean the ISV - my cab did exactly that and after a blimmin' good clean (took me two goes) it was fine for 40k miles and still was when I sold it.[FONT=verdana,geneva"] [FONT=verdana,geneva"]The ISV is under the intake runners between 1 & 2 and you can get it out without disturbing very much - even I managed and I have sausages for fingers. Give it a good going over with carb cleaner to get the varnish off and you'll be sorted I bet.[FONT=verdana,geneva"] [FONT=verdana,geneva"]I had a problem with my 306 a few weeks ago where it would either die at idle or may sit at 2,000 rpm. Same thing, clean the ISV and it's been spot on since.[FONT=verdana,geneva"]
 
Will give this a go when I've not got a 3 nearly 4yr old nagging me and report the results.
 
I remember when I had my RS500 in the late 80's, being in slow moving traffic just as I entered the Dartford tunnel.

The Idle speed valve decided to stick fully open and I had to do the entire stop-start journey through the tunnel at 3,500 RPM with a somewhat 'race spec' exhaust system that makes WUF sound socially acceptable [:D] [:D] [:D].

I had to disconnect the valve when I came out the other end of the tunnel and had somewhere to pull over.

Usual cure - a liberal squirting of carb cleaner and it was as good as new again !

Happy days [:)] [:)] [:)]

 
Don't delay too long.

My S2 started doing this about six years ago. My mechanics said it was the ISV but that the intake had to come off to get to it which was lots of labour.

When I finally had enough and said 'ok do it', they DID manage to get their fingers in there without removing the intake but the ISV was so seized up that it needed replacing [8|]
 
Can someone please post a picture to show where the ISV is I think mine may be starting to stick. Very occasionally when started warm my car will fire & then idle for a few seconds then cut out.
 
Here's a couple of pics that should help. Looks very tight under the inlet manifold and I haven't got Fens sausages [;)]




465A5B68D2DA4B37BC1CE25E89962741.jpg
 
And here's a close up with the part no. When I looked it up on the (US) Bosch site the part no. is slightly different being "0 280 140 514" and referred to as an Idle Speed Stabilizer




84AF33D8BD0B4D5C87EC82E9B42555C0.jpg
 
So is it just a case of pulling off the black connector and cleaning it or do you have to undo the whole thing?
 
No, it's not electrically dirty, it is varnish caused by years of fuel/air mix and heat. You need to take it off completely and the working of it is a cylinder with a hole through it that rotates. You need to clean that up so it is shiny and rotates freely.
 
Graeme, did you have a go at cleaning your ISV yet? If it stays dry tomorrow i'm going to attempt to clean the one on my cab.
 
Not yet, I may have a slight fuel leak in the lines around the rear axle & that is going to take priority.
Please post how you get on doing yours.
 
ORIGINAL: 944turboS

Not yet, I may have a slight fuel leak in the lines around the rear axle & that is going to take priority.
Please post how you get on doing yours.
Click to expand...

Well i've had a good took at this today and bought my can of carb cleaner in readyness.
There's two hoses going to the isv (one looks quite hard to access) but the diificult bit looks like the rubber backed bracket that actually secures the isv unit - The head of the bolt that secures the clamp on it looks very difficult to unscrew.
The weather forecast seems to be good for the early part of next week so i think i'll attempt it on monday or tuesday.
Anyone know the cost of these brand new?
 
Right, i have a damn good look around the isv this morning and i'm very doubtful that i can undo the bracket that's holding the unit in place - it looks like it must have been fitted by an "umpa lumpa".
So, does the "panel" think that if i undo the hose on the base of the isv ind liberally spray the "carb and choke" cleaner in, reconnect the hose and run the car this would be sufficient or is it likely to cause the motor to idle worse?
Any thoughts?
 
I don't remember exactly what was involved but I got mine off. Even so it took 2 goes to get it sufficiently clean. By all means try spraying in where the hose comes off but don't expect it to work 100%.
 
ORIGINAL: Fen

I don't remember exactly what was involved but I got mine off. Even so it took 2 goes to get it sufficiently clean. By all means try spraying in where the hose comes off but don't expect it to work 100%.
Click to expand...

Do you think that it would run worse though fen?
 
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