Porsche Enthusiasts Club Forum

The 944 s2 has irratic idle. What do I need to do to but this right?

Look for vacuum leakes for starters. Air creaping in from intake gaskets, etc. will mess with the fuel mixture at idle.

Second, make sure your oil dip stick is full down and sealing. Oil filler cap too.

I will do that thanks.

Is it possible the air flow meter is causing these issues?

Could be idle control valve, not sure where its situated on the S2, but usually a flush with carb cleaner helps

you should be able to see the idle control valve if you look in between the front two inlets if i remember correctly.

It could be many things. Can you define "eratatic idle" with a little more detail?

The AFM certainly can cause Idle problems. On my S2 at 150k miles the resister tracks were worn through which can cause false readings. There is loads of stuff on the web on moving the wiper contacts to use a fresh piece of track, and on mine just moving the wiper assembly down on the shaft was sufficient. (the S2 AFM uses 3 x contacts rather than 2 x as per info you see on web but principle is just the same).

All this is quicker to do than removing cleaning and replacing the ICV which is awkwardly located on the S2 , and on mine at least sorted poor idling

While the AFM is off your'll see the air by-pass screw (covered by blue blanking plug), so the idle mixture can be adjusted, screw-in to richen. You cannot see this when AFM is in situ and after extended mileage it may well need tweeking slightly from factory settings for best idle

Mike

I will make a video clip of the rev counter on idle next time I take it out of the garage.

Is the erratic idle only when the engine is cold, or is it all the time ?

I haven't used the car much so can not give an accurate answer but from what I can tell it is more of an issue when it is cold but sometimes also when it has warmed up too.

I fired it up earlier to film the rev counter but the idle was fine.

The revs don't drop to a point where the engine will stall nor does it increase excessively.

If its when its cold I would be tempted to say either an idle control valve problem or a vacuum leak which self seals as the engine heats up and things expand

A bit of an update on this. I have used the car a few times over the last few days and have noticed the idle is fine for the first 30 seconds or so after starting. Then idle is bouncing between 600 and 1200 sometimes even stalling when the revs first drop.

After 20 minutes the problem clears and it idles perfectly. Although I haven't used it for any longer than 45 mintues per drive.

I recently fitted a new air flow meter, Bosch super 4 spark plugs and checked the air filter, dizzy cap and rotor all of which made no difference.

Where is the idle control valve located and how do I get to it as I think that is my next step.

ICV lives under the inlet manifold between the front 2 inlets IIRC, not sure if you can remove without removing manifold on S2, earlier S you have to remove inlet

Look between the inlet runners 1&2 as they go into the head and you wil see the cylindrical ICV, with connector attached. Getting it out is do-able, but involves swearing and grazed hands.
Remove the connector, and loosen the clamp holding the ICV, and disconnect the hoses - one at AFM hose , the other at the manifold. Then start swearing as you try to wriggle the ICV out.

Once out clean it with Carb cleaner - fill it up and shake it until there is an audible rattle, which means the gunge has been removed. The Carb cleaner has lubricanant properties so its all you need - don't use WD40. Refitting is the reverse proceedure, but harder..

Mike

Tried to remove the ICV this morning and it appears to be a case of removing the inlet. How difficult is removing the inlet?

Will removing the pipe from after the airflow meter that leads to the ICV and spraying carb cleaner into this pipe do the job?