AGGGH! My S2 Idles Crazily!!!!!

[Guest]

HELP, PLEASE! I have a 1991-H 944S2 which runs fine when cold, however, the same can not be said after its warmed up. It does not idle steadily, and can in the worst case cycle between about zero and 3000rpm when you are stationary. The result of this is that more or less every time you approach standstill, it cuts out (this can be up to about 15 times in a 10 mile journey - can sometimes beavoided if you put your foot on the accelerator whilst stopping, but this is rather tricky!). It does, however, always start again, and once you are at driving speed, it is absolutely fine (i.e. it has never cut out when driving along). My initial guess was that it was the "˜idle adjust unit', however, I have since been told that this can be ruled out on the grounds that this unit only operates at revs up to 1500rpm. Any ideas??!!

 

[sawood12]

My idling has been creeping up to around 2k rpm recently. It wasn't irratic and mostly would idle at normal levels but every now and again creep up. I've had a good tinker today and found the idle adjustment screw in the throttle body was vey loose and seemed to be working its way up and down with the vibration of the engine. I've replaced the screw with one from a breakers and so far it is stable.

One other possible cause is a split in a pipe or a leaky joint upstream of the air flow meter. Go round the intake hoses with a can of WD40 or carb cleaner and give areas a bit of a spray and listen for a sudden rise in idle rpm which could indicate a split somewhere sucking in unmetered air.

 

[edh]

As well as looking for air leaks, it's worth checking that the Throttle position switch is working OK

have a look at
http://www.clarks-garage.com/ - the garage shop manual - Throttle position switch.

I don't know if it helps, but Clarks garage also says "The 944S and S2 models use a system called "adaptive idle speed volumetric efficiency regulation" and do not require idle speed adjustment."

 

[eitnurg]

I've also had these symptoms - caused by a failing temperature sensor.
My heartfelt advice is - take it to a man who knows, & who can test the system properly. Believe me, you can drive yourself absolutely insane trying to work it out yourself!

 

[Guest]

*** UPDATE! *** Now does it when it is cold, too []

 

[Diver944]

Take it to your nearest specialist - it won't get better by itself and will only get worse, potentially damaging something else []

You don't say where you are in your profile or signature so no-one can advise you where your nearest specialist is [&:]

 

[Guest]

I'm just North of Bristol (Yate)

 

[Fen]

I'm not sure there is anyone in Brizzle with a good reputation (happy to be corrected if anyone knows different, though I got that from an owner who lives there). You could try Steve Bull in Devizes or Andy Moss (who I use) in Honiton.

 

[944turboS]

I've heard good things about Steve Bull, there was a new place in the front pages of PP this month north of Gloucester as well.