Porsche Enthusiasts Club Forum

Guys,

odd issue with my S2.

It starts fine, runs fine for maybe 20 mins, then when I stop at lights etc the idle varies between 900 and 400 RPM & sometimes stalls when I'm braking to a halt etc.

I can keep it running smoothly at say 1100rpm with a touch of throttle.

Restarts instantly when I turn the starter. Whilst its doing this it also seems a little hesitant to accelerate at higher revs - not much though.

After a few mins, problem goes away and the car behaves perfectly.

Issue sometimes reappears for a few mins later in the journey - Eg on a 150 mile journey on Saturday I noticed it only at 20 mins and when I pulled into the driveway at the end.

This started (maybe coincidentally) when the AFM was changed a few weeks back.

I have had the AFM off and looked t the track/contacts etc, all seem good and checked that none of the vac lines are loose. I've also had the idle control valve off and checked that works as its supposed to - it does.

I'm thinking its temperature related as it seems to start just after the temp gauge gets up to its standard position - but then the AFM was a coincidence?

Its a niggle now, but as I'm heading off to France in it in a few weeks I want to make sure its not the beginning of a more problematic fault.

So, any ideas please?

check the rubber pipes either side of the idle control valve - sounds like you may have a leak/split somewhere.

An air leak around the ICV or even after the AFM could be the issue there. Good luck

Btw, not sure the experts on here are that idle

check your idle sensor on the throttle body
http://www.clarks-garage.com/ look up fuel-06 test procedure
Steve

Thanks guys,

I'll be checking all those suggestions.

I thought it may be temp related so fitted a new DME temp sensor. I thought that had resolved it as I didnt get the issue after the first 15-20 mins as usual, but it did occur briefly later.

Could this be something to do with the sensor that sits just behind the distributor at all?

The connector that sits on the bracket is missing its wire retaining clip so it comes loose very easily.

I did try disconnecting it when the engine was idling normally but it didnt effect the idle.

I just researched that sensor near the dizzy - Hall sensor. Apparently nothing whatsoever idle related.

So i noticed I do seem to have a fairly consistent but slight "hesitation" whenever I come off idle - so Im thinking the TPS is the culprit now.

This looks changeable without much dismantling on my car - but maybe i'm wrong as Clarkes suggest the throttle body has to be removed.

Has anyone changed a TPS and what was involved?

I,ve had exactly same problem for years on mine also Ian...changed maf, icv and hoses,checked battery ground strap ...nothing ....my mechanic is stumped and considers the issue to be much deeper inside ...Ive learned to bear with it (just about) , im very goood with the clutch in slow traffic..! If you find a solution do post it up ..Best of luck Ciaran Fla.

I'm about to fit a new TPS to the 968 and I believe it's a relatively straightforward job... Just two screws....

I replaced mine earlier this year and it was dead easy.

David

Great,

just watching the letterbox now.

£76 for a genuine Bosch unit off Amazon.

Well, fitted new TPS (it was indeed just 5 mins). Also removed the ICV (that took a bit longer!) , cleaned it with carb cleaner and tested it with a 9v battery - all seemed OK.

The low fluctuating idle has gone, but instead when it gets warm it idles around 1400 most of the time. If I blip the throttle it usually settles down to 1100 - but before all this started it would sit happily at 900.

Any more ideas guys?

Your accelerator cable could have been adjusted for idle without the TPS sensing idle position,

TPS needs setting correctly

OK Guys,

I'll take another look at the TPS adjustment (& throttle cable), but I did make sure it was clicking when the throttle was closed - maybe I should recheck it when everything is hot.

Thanks