mistergos

hi there.
i am new to this forum and need some advise. been reading
through some "stalling" posts but none really suits my problem.

i own the 911(stock) for around 2 years and it has always had that problem, sometimes more often than others.

the car always starts fine, perfect idle, no smoke or rough sound.. i drive away and after maybe 5 - 10 mins, sometimes even longer, the car suddenly stalls. regardless of current speed, or revs. than i try to restart, it cranks and turns over, but it wouldn't s start. i have to wait and sit for 2-4 minutes until the car starts up again fine and the engine runs fine thereafter without any stalling. only, when, for example , i park the car for 2 hours, after a 4 hour ride, it happens again, when i recommence my drive, like described above. sometimes, though rarer, it also does it when the engine is warm, after a short brake, at a petrol station, or so.

i would appreciate any helpful comments. i now get really t nervous nowadays, when i take the porsche out because i have been stalling in the weirdest situations on the road, while overtaking on the highway, in the middle of of a busy junction, at a red light, after it's turned green, and so on. it is not only embarrassing, it is dangerous!

thank you.

mistergos

Peter Zimmermann

This sounds like one of those problems that probably can't be diagnosed. If it were my car I would have the sensors at the flywheel, the cylinder head temp sensor, and the DME relay replaced. That gives you a good baseline from which to work, but I think replacing those items will only have about a 75% chance of curing the problem. You're right, it's a dangerous problem, and should be fixed ASAP.

KC911

Since all 3.2 owners should carry a spare DME relay anyways (that's KNOWN to be good) in order to avoid getting stranded (i.e. cheap insurance at $30 or so), that's what I'd start with (since it's so easy). It's a potential candidate for the symptoms you describe too.

Keith
'88 CE coupe

CharlesJones

Hi Mistergos,

I think Peter's advice sounds good, but what have you tried so far? Have you changed the DME relay at least? I've heard that it is usually the first thing to try, although perhaps you've tried replacing it already.

I had a stalling problem in my 911 not long after I first go it. It would occasionally randomly die when I coasted up to traffic lights etc. It just seemed to stop happening with me though when I started to use the car more, so I'm not sure what the problem was.

I remember reading in Porsche 911 World about one of the writers who had a 3.2 which was always stalling, and the symptons sound similar to yours from what I can remember. Like you he just lived with it for months dues to all the hassle of trying to diagnose it, but in the end he fixed it by buying a new AFM. I expect AFMs are pretty expensive so I wouldn't recommend replacing it without evidence that it is causing the problem, but it is a possible cause. I'd recommend doing what Peter suggests above, and if that fails maybe popping the guy at Porsche 911 World an email to ask him what his symptons were to see if you might fix the problem with a new AFM. I'm just trying to remember what the guys name was - I think his surname was Allen, and if so you'd be able to find his email address in the front of P911 World. He's the chap who now runs the pink 964RS in the magazine, so you should be able to find him.

Good luck.

AJ88CAB

+1 on the DME relay.

Your's are classic symtoms, intermittant stalling/not starting for a while then one day.......you're stuck somewhere...... could be tomorrow could be next year.

You should carry a spare DME relay anyway, so get it, try it, if it's not the problem you have your spare. If it is, buy another for the glove box

Good Luck

3.2SLANTNOSE

I wonder if it could be a bad or clogged fuel filter? Have you ever replaced the fuel filter? It shows somewhat of the classic problems with a clogged fuel filter, starts ok and runs, till the sediment builds up on the filter, then engine gets choked out from the clogged filter, then after it sits for a while, the crud settles and allows fuel to pass again, till it gets stopped up again. You might have a lot of loose crap or scale deposits in your fuel tank. Keep us posted. Good luck!! Tony.

mistergos

thank you guys!

i am on my way.
have already replaced the relay under the seat.
still stalling... next stop flywheel sensor.

will get to the bottom of this ( i hope...)

determination helps. will get updates in.

thanks again

goswin

speednme

I had a similiar problem when I had my 85 911 turned out to be the fuel pump. If this has never be replace it might just be your problem. The car is 19 years old.

good luck

scarceller

Mistergos,

Next time the car dies look at the tach while you are cranking to see if the tach bounces. While cranking if the DME has power and is functioning properly it will send the signal to fire the coil. This same signal is also provided to the Tach.

I also suggest you remove the Fuel Pump fuse and crank the engine and observe the Tach to see exactly what you are looking for. This way you will understand what and how the Tach bounces while cranking. The Tach needle does not move much but it does move while cranking.

So the idea is to know what you are looking for at the tach while cranking. Then next time when the car dies you can see if you have a tach signal. If you do not, you have some sort of electrical issue with the DME or DME Relay.

Also, both the DME and the Relay are known for bad solder joints. Often the solder joints crack, many theories on why they crack. But my oppionion is they crack because of stress from having the DME bolted directly to the Floor Board under the drivers seat. This mounting arangment causes the DME to feel every bump and shock in the Road. Others feel these DMEs may have had Cold Solder joints from day one.

Hope this helps.

88911coupe

DME relay is a very safe, cheap place to start. I had a similar problem on my '87 and it turned out to be nearly invisible breaks in the solder connections inside the actual DME unit itself. They would randomly come apart and the car would die. This was sudden, out of the blue, engine shut off, no warning or odd running which may preclude a problem with the fuel filter or something like that. Dealer tried to charge $1,600 for a new one but thankfully I found a detailed solution on Pelican to fix it but I suspect it's here as well.
Good Luck,

3.2SLANTNOSE

No one else thinks that this could be a fuel filter getting blocked? Very strange, I would have thought that there would have been more people suggesting a blocked fuel filter. O-well, I guess he will keep us posted. Good luck with it!! Tony.

KC911

I think many of us started with a potential "likely" culprit based upon our familiarity with the 3.2s. The DME relay (also contains the fuel pump relay) but since he has already replaced that "weak link", your suggestion should definitely be on his "check list" too imo.

Keith
'88 CE coupe

scarceller

I simply propose not changing anything till you do some basic diagnostics and testing at the time of the failure.

This is why I mentioned the very simple test of looking at the tach while you are cranking at the time of the failure.

If the tach needle stays completly still and does not bounce at all then you know something is up with the DME. This helps point you in the right direction. As already mentioned this could be electrical/ignition based or fuel based. But if that tach needle does not move while cranking it indicates some sort of failure in the DME box or Relay. BUT if the tach does bounce this does not completely rule out a DME failure as the tach COULD bounce and the trouble still be in the DME.

I just am suggesting you keep an eye on the tach needle should the condition re-occur.

Hope this makes sense.

KC911

You're suggestions are excellent (I learned something new ), and make perfect sense. I think a lot of us suggest the DME relay "just because" it's a good idea to always have a spare along on these 3.2s anyways. Thanks for the pointers!

Keith
'88 CE coupe

DonMo

I would also find a friend with a 3.2 motronic ecu and see if he will let you swap. I chased a gremlin with my 3.2 and found it was a bad transistor in my brain (cold solder joints do the same).

I would lend you mine but your pretty far away.