Jeff928S4

In a thread (that I can't find) about a bad idle, someone stated that they changed the Idle Control Switch. They said it was that part behind the drivers side headlight that sits on a metal "plate".

I can't find any listing of this part and those I have asked have said it was an ignition module, not the Idle Control Switch......yet on the Vacuum hose diagram on the passenger side wheelwell (that silver sticker), it shows a "Idle Speed Control Valve" in that diagram on the far right bottom. From this valve, you see a line going to the intake manifold (in the diagram).

Anyone know where this mysterious Idle Control Switch is on a 944 S???? It's not the Idle Stabilizer Valve, by the way.

944S Boyeee

jason_87924s

The ICV is under the intake plenum. The part can be replaced without removing the intake, but you have to be creative. Otherwise you will need to remove the fuel rail and intake to replace it.

Jeff928S4

Isn't the thing under the intake manifold the Idle Stabilizer Valve???

944S Boyeee

jason_87924s

I believe that the ISV and the ICV are one in the same...someone please correct me if I'm wrong.

led

As I understand it, they are the same indeed

7thStranger

I think one is pre 85 and the other is post 85.
Not sure which is which.

Jeff928S4

I have an old work order from Porsche that the PO gave me. It stated the car needed an "Idle Stabilzer Valve" ($400) and a "Idle Control Switch" ($104).

Am starting to think this "Idle Control Switch" is the Throttle Position Switch.

944S Boyeee

pete944

The S2 has that same module right behind the driver's side headlight. What exactly is that little bugger?

Jeff928S4

I've been told it's an ignition control module, but I've also heard it's a Idle Control Switch.

Could any S or S2 owners do me a favor??? Look at that silver sticker on the wheelwell above the windowwasher reservoir.....does it say "Idle Speed Control Valve" on that sticker on your cars???? Does anyone know where that would be on the car? It's part of the vacuum hose diagram.

944S Boyeee

ringo951

Is this what will fix an erratic idle, such as idling around 2000 for a little while then dropping back to 900, then jumping back up to 1500 or so. Is it located under the intake manifold on a 951.

jason_87924s

Ringo,

Barring that you do not have vaccum leaks, this should fix the erratic idle problems.

Jeff928S4

Yes- the Idle Stabilizer Valve (under the manifold) will either stick open or closed causing a low or high idle.

I just had mine replaced and the old one idled at like 450 most of the time and would dip to almost stall a lot - did it ever suck!!!. The new (well, used) one idled at 2000+ when it was first put on - it was sticking due to it being inoperative for a bit, but now runs perfect.

The labour on the replacement is around 3 hours max.

944S Boyeee

SoCal Driver

From what I can tell looking at the electrical schematics there are three different idle control valves.

Pre 85.5 944's have a 12 vdc heated bi-metalic spring that closes a knife valve; post 85.1 944's (951's, 944S's, 944S2's and 968's) have a push-push (bidirectional pulsed needle valve) then some have a single direction pulsed needle valve.

The schematic for the 83 944 calls it the Supplementary Air Valve.

After 85.1 it's called an Idle Possitioner

The pre 85.5 (or early 944's) ICV current comes off the same circuit as the fuel pump.

The post 85.1's are directly controlled by the DME.

Kevin Baker

Boyee that part is called the ignition control module, or ignition transistor. It is unique to the S2 and the 928 (they have 2 one per cylinder bank). I have lost the part # but, it does have a 928 group in the part number. Do a search on ignition control module, there is a guy in Dallas (not Matt) that I gave the one I had to. I do not know if he used it or not, as I dont remember if he has an S2 or not, look him up and see if he's using it. At any rate, it should run about $60.

Kevin Baker

It is located on the frame rail directly in front of the A/C dryer.