garrett1021

I have been problem free in my 964 for about 2 years now and now I'm struggling with an annoying problem.

So... this is the exact sequence of events:

I started my car, drove it around for about 2 hours no problem.

I stopped to go to one of my uni classes, and when I went back out to start it, everything went fine.

I made it out of the parking lot and pulled along side a corolla at a red light, it was full of college kids and me being in a straight piped porsche I'm sure it garnered some attention.

I succumbed to their requests and revved it up a bit for them, going no where near red line.

When the light turned green I was unable to press the gas more than about an inch before it would dip into sub 500 revs and feel like it would stall.

I made it home no problem, just had to make sure I gave it a small amount of gas.

As I'm writing this, I'm looking at my car as its running (it starts up 100% of the time)

And on idle, you couldn't tell there was anything wrong. Everything SEEMS perfect until I try and give it some gas.

What could possibly have happened?

Thanks, Garrett

crg53

No expert on these sort of problems, but my first guess would be that your idle microswitch is not working correctly. With the engine not running, open the hood and move the throttle by hand, you should hear a "click" as the throttle arm moves away from the microswitch. You can search for how to diagnose problems with that switch.

dhc905

That usually throws a check engine light. It did for me.

tbennett017

Also make sure you don't have a vacuum leak between the AFM and the intakes. It sounds like unmetered air?

Goughary

Check the wiring behind the afm. There was a tsb that needs to have been performed on the plug

Duck

Do you have a scan tool or similar? I have a PDT-999 and looks like we are in the same city. If you do not have a tool to read fault codes, you are welcome to use mine.

twilight

Mine had the exact problem and drove me crazy - the micro-switch was the answer, believe two were replaced....send me a note and I will look up the exact part numbers. Car drives brilliantly now , almost as nice as the two Singers here in Minneapolis!

Goughary

There are two singers there?

Navaros911

6 hours after I read this, I have a similar issue.

Starts fine, idles ok, almost stalls and stays in very low rpm like around 500 if I try to drive off. If I can get it over 4k rpm it feels fine.

So drove it like I stole it to work.

Will check a few things on the way home.

Now all is good again. So for sure electrical. Will check micro switch and afm connector. It is a 1994 car, so no tsb required.

D.C.

CRG53 is spot on with his suggestion.
Your symptoms are classic for a bad idle microswitch.
That switch tells the DME to use the "idle" fuel map when the throttle is closed. when the switch is not working, the DME stays in idle mode even when you step on the go pedal, causing a lean fuel condition.
It is easy to check, and very easy to fix.

ThomasC2

also check that the throttle wire moves freely so the throttle linkage actually reaches the micro switch.

Robbrizzle

I recall having a similar issue and it was the Mass Air Flow Sensor. From recollection, I think you can test it by unplugging it, (the engine will run rough, limp home mode) but you should be able to get higher revs. Bosch did a remanufactured one, on an exchange basis for about £150 (a couple of years ago).

Bertrand

Check secondary distributor is working. It reminds me a bit of the problems I had when the belt broke in mine. To check it, engine stopped just remove the 12 V from the main ignition coil and try to start the car.

dhc905

^^ Distributor belt?

GeorgeK

Same symptoms as the OP, same solution as robrizzle for me.