I just got a 944 at 83K and it's left me on the road twice now. My mechanic (not a Porsche expert) has already put in a new battery and ignition coil. The car cranks but won't start unless jumped. Then it'll run for a while, but eventually it stalls and doesn't start.

I've read the various postings and I'm convinced it's one of the sensors. You've named the following: Crankshaft sensor, Fuel pressure regulator, Speed/ref sensor (I can't seem to locate any kind of part by this name at the usual chainscould it be called something else?), and finally the Throttle position ref sensor. I figure it's gotta be one of these. I'd like to guide my mechanic correctly so that we're not out a couple hundred bucks trying to replace all of these sensors. What should he look for first and how should he test it?

I'm not very tech savvy, so please use the most basic of descriptions. I've owned BMW's before (and love them with a passion) so I figured that I'd like the Porsche too, but the experience so far has left a bad taste in my mouth. Help!!

Gal who likes German cars

 

First of all, do you have some kinds of maintenance records of the car? For example, timing belt services, tune up, etc.
After the car is being jump started, does your mechanic check the battery voltage with the good multimeter? It should read
13.5V or more. Make sure all the battery connection is tight, the battery clamp is in place.

I suspect your main relay is bad. At the moment , do not try to replace all parts yet that you mention here without testing it.
If you are in a budget and decide to replace the crankshaft position senors. 1984-1985 BMW 325E's sensor will work fine. The cable
is just little bit longer.
You can get more info by suscribing the alldata.com.

 

I have just experienced the same problem with my 1984 944 (or at least similar in your description) but there is no way to 'guess' whatthe solution iswhenthe problem is"stalling" (it could be many things)... butI was driving along the highway New Years Eveat a moderate pace(5th gear @ 2400rpm) when the car just 'shut off' on me, gliding down the road until I pulled to the shoulder. I tried to start the car repeatedly but it would not turn over. I gave up and called my wife to come and rescue me. While sitting and waiting for her to arrive,just staring out at the traffic for a few minutes, I decided to give it one more try, the car startedinstantly. 5 minutes down the road, again the car just shuts off. Tried to start a few times, but nothing. Waited a few minutes and the car started like it was new. I have been told that this could be a number of issues that are common to the 944 such asfuel pump relay, ECM relay (later models), ECM module (the engine's computer) or even as simple as acap and rotor. I will have to waituntil my Porsche tech returns from holidays to find out.

 

Sounds like a bad DME relay to me.

 

Thanks 'grayghost', that's a unanimous first guess, also made by a very respected Porsche 944shop here in Toronto. I'm hoping that it isjust the relay... the only thing that's bothering me a little, is while driving the car the next morning to the garage the samestalling began to occur but this time I kept on the gas and the engine just shutteredyet keptrunning then suddenly began to run fine, then again a few minutes later it began to break down again but I didn't clutch, I kept on the gas and she just seemed to be missing really badly (chugging)until it just suddenly starts runningperfectly again. I'm not sure ifa badrelay would act like that, I'm toldthat it would either shut off or on, not create intermittant missing. Oh well, I'll find out Monday.

 

(Update) Thenew DME relayhas solvedthe problem.

 

i have a 1985.5 944, and i just got it, and it turned over but didnt start, i changed the fuel pump and fuel injectors/rail, and now it runs.