87 944s idle problem

londel · 07-19-2003, 09:56 PM

Hello,
Im a first timer. I have an idle problem with my 87 944s. 86k. Recently had cylinder head rebuilt and all 16 valves new. It has had the problem since I bought it 2 years ago. When I pull up to a stop light the idle drops and sometimes the engine stalls. If it doesnt stall it will quickly recover and idle normally. I have already installed a new idle air reg. under the intake manifold, but that didn't fix it, although it seemed to improve for a month. I know theres a Porsche tech out there with the answer. I read a post somewhere that it was normal and a chip would fix it. What do you guys think?

TCMdocs944 · 07-19-2003, 10:01 PM

Welcome.

Put some info about your car in your signature line so we can help out a bit better.

First check in my opinion, given the age of the car is ALL vacuum lines. Check for connection and brittle or broken lines. Check the alien(air intake) hose. If that fails check the electrical connections to the different dme components.

Basically, your DME(brain) is reading the wrong signals.

Mark

londel · 07-19-2003, 10:06 PM

I have checked for vacuum leaks with choke cleaner and I checked the air intake hose from the Mass air flow to the throttle body but couldnt find any leaks. I'll check all the sensor conn. Thanks

TCMdocs944 · 07-19-2003, 10:10 PM

If that fails there are several vac lines under the intake manifold that are subject to heat deterioration.

Another obvious is grounds. If you have no other electrical symptoms this is probably a blind alley.

Good luck

carsontc · 07-20-2003, 08:47 AM

and check Clark's (http://www.clarks-garage.com)

Idle adj at:

http://www.clarks-garage.com/shop-manual/fuel-08.htm

TPS test at:

http://www.clarks-garage.com/shop-manual/fuel-06.htm

and FRWilk's (http://www.frwilk.com)

AFM test at:

http://www.frwilk.com/944dme/afm.htm

MrPants · 07-20-2003, 01:32 PM

isnt this what FR WILK's shudder fix chip is designed to fix?

carsontc · 07-20-2003, 02:37 PM

good point...the DME 'learns' the 'conditions' and adjust to them...and must have the battery disconnected and then reconnected to re-learn...which takes about 10 minutes?? so to adjust to the new part it's best to 'reboot' via a 'power cycle'

londel · 07-20-2003, 02:48 PM

Hello I have had the battery out since replacing the reg. but I have also been driving the car for about 4 months since replacing the reg.
I know that on some GM cars there is a min. air rate adjustment that allows enough air to by pass the air reg (when fully closed) to maintain a min idle speed of around 500 rpm or so. I havnt been able to find any such adjustment on my Porsche, Does anyone know about this?

carsontc · 07-20-2003, 03:19 PM

in response to "Scott, Can you tell me where the idle adjustment screw on the S is located" (from another website)

Quote:

Originally posted by Scott Anderson
It is right under the throttle cam, on the throttle body, at the very back of the intake manifold.

londel · 07-20-2003, 04:30 PM

Thanks, so it sounds like I would adjust the throttle plate open to set a min air rate and then reset the Throttle position so it reads closed at the new setting. Is that correct?

carsontc · 07-20-2003, 07:26 PM

Quote:

Originally posted by londel
Is that correct?

I can't say…never did that one

ask SoCal and if he tells you to jump off a bridge...don't even appear to hesitate

hey Juvay is back…now where is Todwic ??

(I hope one of those jack stands he’s so fond of didn’t slip ! )