Niagara

Hey guys, I searched threads first before I posted.

I have an 87 944S and I need to find the idle control valve so I can try a good cleaning before I replace it.

Symptoms are typical high idle, and doesn't want to rev down when the gas pedal is released.... it slowlyyyyyyy comes down.

fezz

under the intake manifold.

before you remove everything, try giving it a few wacks with a screwdriver with the car running - may stir up the crude and buy you a little more time.

gtroth

Yeah, it's under the intake manifold. Pretty tough to get to on the S.

I guess those symptoms could be the ISV, but I think more typically it fails the other way (won't idle high when cold, idle drops too fast comming off throttle /maybe stalling...).

I would look very carefully for vacuum leaks (measure it if you have a gauge).

darren1031

gtroth,

what do you get for manifold pressure at idle?

I measured mine today at the vacuum line connected
to the brake booster. Initially, it started at 10-11" and
as the car warmed up, it rose to 14". Of course, it
ran like crap. I have no idea why my pressure is so low.
I've replaced just about everything.

Darren
'87 944S

gtroth

That does sound low.

I tee'd in at the fuel pressure damper since it's right in front and easy to get to. After sealing everything up as best I could I got:

16 inHg at idle
19 inHg while reving

Here's a thread I started on the subject:

vacuum

I've read a few threads on hunting vacuum leaks, basically spay carb cleaner or propane at suspected leaks and if the idle goes up, there's the leak. If the ISV is working, however, it would in principle compensate and hold the idle steady, so I believe they say to unplug it for this test. Better search on this before listening to me.

Good luck.

nine-44

Possibly the throttle position sensor as well..

There's a post about that right now, a little looking and you'll have all the info for that stuff as well.

darren1031

Not the TPS. I just replaced it.

I've been trying to track down why my idle is so bad.
It will be relatively steady for awhile and then all the
sudden you hear the rpms increase slightly followed
but a drop in rpms with the engine almost cutting off
and then it feels like the idle stabilizer kicks in and
stabilizes the idle for about 5 seconds and then it
repeats.

All sensors have been replaced. All ignition components
have been replaced..including AFM.

I just dont think my manifold vacuum should be this low.
I may have to do the starter fluid trick soon. I'm just nervous
about spraying that stuff around my engine.

Darren
'87 944S

ross944S

Mine does the exact same thing Darren, but I haven't replaced the AFM or TPS. I haven't measured vacuum. I'm guessing its the stabilizer but I don't really feel like spending the money without knowing for sure.

gtroth

Did you rebuild the throttle when you replaced the TPS?

The reason I ask is that when I did that, I didn't align the throttle plate with the throttle bore perfectly and it rubbed. I could barely feel it, but it caused the throttle to not quite close and the TPS not to engage. Now here's the kicker - testing the TPS by pulling the throttle cable (I put a meter at the DME connector) did not show a problem (clicked, meter beeped). But when pushing the accelerator pedal, it failed. This caused the idle to wander around and bounce.

ross944S - my advice to you is to get your hands on the DME Diagnosis and Trouble Shooting Guide in the Factory Service Manual and measure everything you can.

darren1031

Explain rebuild. I cleaned it up and replaced that large O-ring. There was no binding on the throttle. When I installed the TPS, I adjusted it so it clicked as you barely moved the throttle plate and clicked again when released. This was how it was set prior to removal too. I'm pretty sure this is adjusted right.

I did notice recently that my new TPS already had oil on it. Why would I be getting so much oil on my TPS? I did replace my oil filler cap with a new one last night. I wonder if a bad seal there would cause and excessive amount of oil to come through that hose connected to the oil filler.

gtroth

There's a throttle reaseal kit from Paragon (also Arrnworx, I think) that has new seals for the throttle plate shaft. To replace those seals, you have to remove the throttle plate.

I would not expect your big leaks from bad seals there, but who knows. I only mention it because my car behaved like yours when I goofed up and my throttle wouldn't close and actuate the TPS properly.