Porsche Enthusiasts Club Forum

I'm trying to lower my idle speed on my 944S before I take it for it's first MOT since I've been restoring the car for the last 6 months.

I searched and found there isn't a need to adjust the idle speed on the S and S2 but mine currently sits about 975rpm when it states it should be around 800 +-50. I would like to lower it to the correct setting for fuel saving reasons and just in case it messes its MOT test up on emissions.

I've tried adjusting on the throttle cable and the butterfly but none of these lowered the idle. Is there a valve somewhere I can adjust to bring it down, I can't see anything?

I don't think the MOT place will care too much about the idle as long as it is below 1100rpm for example.

However, here is a guide for you to adjust it with. I'd also check for air leaks (inlet manifold gaskets, vacuum likes, ICV lines and even the throttle body gasket) but I doubt it is your issue with the idle being slightly higher:

www.clarks-garage.com/pdf-manual/fuel-08.pdf

Thanks for that, I was just worried that the car hasn't been driven for 8 months and will be driven straight to the MOT station without an "Italian tune up" on the way. My worry is, with a higher than normal idle it may fail on its emissions idle test, I would also like it to idle at the factory setting if possible.

I have had a read of the CG document but I still can't find the idle screw on my 944S, does anyone know where it is hidden?

Can you take a photo of the throttle body? That may help.

Hi, the CG procedure does say that it doesn't apply to S and S2 cars. The only adjustment you have on a 16V car is the air screw on the AFM body. There is no 'idle' adjustment. So, you probably have a vacuum leak, or an air leak around the idle control valve. There are some unusual rubber hoses with bonded joints, they do have a tendency to split, but look ok. So a good check in that area might prove fruitful..However, you might have to remove the inlet manifold to get to them!!

I have used a torch and searched for something but can't see any adjustment screws.

As was also said I may have to adjust via the air screw if need be but will alos give the vac pipes a check over.

Here are some pics of the area around the throttle parts.

Hi

I can't help in regards to adjusting the idle on an S but I would say if the car has been standing for a while and it's going for an MOT do remember to gently apply the handbrake whilst driving slowly to the MOT station to free up the brake or you'll find that it will fail on it's handbrake efficiency....don't engage the handbrake, just keep the button firmly pressed in and pull the handle up gently to deglaze the shoes and only at very slow speed, do not under any circumstances release the button.

hope that makes sense...

Pete.

I know what you are saying but I've been through the whole car over the last 7 months and have had the rear discs off and cleaned everything up. The handbrake has had a few previous fails and advisories over the years, I noticed when I went through the history files so I made sure it is spot on before it heads for it's test. Hopefully I will get it booked in tomorrow or Thursday and hope the idle isn't an issue.