moldymealworm

this morning, my dad went out to heat my porsche up before leaving for school. when i went out to it, the engine was sputtering, and the RPM's were bouncing from 200-400 RPM. once my brother and i got in the car, it died and i haven't been able to start it up. it shouldn't be low on gas because i filled it up about a week ago. it does get crap for gas mileage and i've been planning on taking it to a shop.

quinnfiske

When did you drive it last? How did it run then? Does it make any smoke like it is running rich?

pa944red

Just a thought, but check the idle adjustment screw on the TB.

Just recently with it getting colder out my '84 would start up fine and run great for 30 seconds and then the idle would get real low and lumpy and then stall out and would not restart. On a side note, once i did getted it started and warmed up the idle was really low.

I found that the idle adjustment screw had backed out almost the entire way, I screwed it in a few turns and now my idle is fine and it starts up normally and idles great, even at 10* F last night.

Tom

moldymealworm

i last drove it yesterday around 3:30. it's been starting up in the cold fine. haven't seen black smoke, but rather a puddle of black liquid forming in an indent on my exhaust.

quinnfiske

It could be any number of things. I would look at all the inputs to the DME. These include:

the DME temp sensor, can cause engine to run rich, is located in the head, intake side, front of engine
the throttle position sensor, a plastic thingy on the throttle body that measures throttle position (suprise!)
the air flow meter, next to the air box, has a "barn door" that can become sticky
O2 sensor, you can unplug it and see if that helps, connector is located at back of engine between the head and firewall

Could also be a fuel related problem like a clogged filter, balky fuel pump etc.

look at http://www.clarks-garage.com/ for some good troubleshooting tips

moldymealworm

the thing is, it usually idles high around 1k-1.1k rpm. it is a 944S and from the looks of clarks, the S doesn't have an idle adjustment screw. i looked through my servic records and i don't remember seeing any replacement for the O2 sensor, so i'll probably start there.

quinnfiske

The idle adjustment screw is on the throttle body near the throttle position sensor. In the 951 it faces up, but may be oriented differently on the N/A cars.

There is also an idle stabilizer. It is under the intake manifold. You can bypass it by jumpering the diagnostic port on the left side of the engine compartment. It is an air valve that maintains an idle by varying the amount of air through this valve. These can get balky also. There is a proceedure for adjusting the idle that explains all of this.

moldymealworm

hmm... before i left for work, i went to turn it on again, and it managed to do so, albeit with a tiny bit of hesitation at the beginning. didn't drive it though, mostly because i was afraid it might die on my way to work.

yellowline

No idle adjustment on a 944S.

Could be a stuck AFM. If the barn door doesn't have the full range of movement, it'll make the car run like that.

xsboost90

yup- 02 might make the milage suck but it would still start. Check the afm to see if the door is stuck.