a new running problem

[Peter Burrowes]

TG this forum is here for people like myself and so many willing to help! The one topic makes me laugh is "What did you do to your car today" and I often think to myself, considered burning it!
So today I am driving down the road and it just shut off and we coasted to the side of the road, but think I to myself it did this last year so out of the glove box I pull the new DME sensor I have there and quickly swap it out, but alas, that's not the problem. I have 2 new ones and the old one, none cured it!
T would start and idle for about 30 sec then die. after about 1/2 hr it cooled off or whatever and ran off and on long enough to get home. There was 1/2 tank + of gas and water temp was normal.
Does anyone have any idea on what this dam gremlin could be? I hate it when I am afraid to go anywhere with it!
Also, anyone know if I can unplug and remove the alarm module without any problem as far as driving it?
Thanks all of you in advance

[mytrplseven]

What's the status of your fuel system? Have you replaced the fuel filter to see if you are getting fuel? It's a quick and easy check. Could also be a failing fuel pump or plugged strainer. When the engine was running, could you romp on it and get high performance or do you simply drive "quietly" around town?

[dave 911]

A buddy of mine who knows 944s says this could be the coolant temperature sensor.

[PorscheNut924]

I had a temperature sensor go bad and all it did was make the radiator fans run nonstop even when the car was off and cooled down. I would have to disconnect the battery every time I left it for several hours or it would end up dead. Finally replaced it a couple months ago.

I would check the fuel system first.

[Peter Burrowes]

the funny thing is, the day before I drove about 50 miles on the highway with NP, and this was about 5 miles from home on the highway
This cars electrics drive me nuts LOL
\

[mytrplseven]

In addition to my initial post, I'll pass along another note or two. DME relays, especially older versions, have been known to be faulty. There's an updated version that should be used. I'm reluctant to think that this is the issue. Also I don't think it is a temperature related issue because it sounds like you were at normal operating temp for some time before the car shut off.

Autozone, a autoparts company, will loan fuel pressure testing kits and I used them to completely test my system, including fuel pressure regulators, fuel dampers and fuel pump and check valve functions (per the tests in clark's garage) and it cost me only an adapter fitting and some clear plastic hose purchased at home depot.

If you have a loose connection on the DME cable or a bad solder joint in the circuit board, this could account for the stoppage that comes out of no-where. A loose connection or defective ignition switch could also be a culprit. You might see if moving the connectors described in this post (while the engine is running) to see if anything changes. Also consider the grounds around the car. Intermittent issues of this sort have been traced to faulty grounds.

[pfarah]

Peter,

Did you have a chance to test the speed and reference sensors? This happened to me over the winter where I was driving along fine then she just cut out and died. Thankfully, it was only 13 miles from the house... Clarks Garage has a good test procedure; a quick test is to view the tach for a "bounce" while turning over the engine. Good luck!

[Peter Burrowes]

thanks again all of you

[Peter Burrowes]

Damm, I have checked it all and it still stalls however I have to add that it seems to be ambient temp related. It only happens when its very hot out. Driving me nuts LOL

[87m491]

"heat related" where you are hopefully is bit less of a problem! Kidding, in my turbo Audi experience, one of the speed ref sensors can get heat soaked when they are getting on in life but will rejuvenate when cooler. We would carry a 2 liter Coke bottle with water to douse the sensor when failed to see if it would then go. The Audi had 2 similar speed ref sensors, one for only start up and one referenced while running. The second was the problem. The other heat issue could be vapor lock, not something I've heard really associated with this car either though. In the turbo Audis this would manifest more often on restart, especially with a weak fuel pump check valve thrown in the mix. Good luck.

[Peter Burrowes]

thanks

[wrench1]

We had the same problems late last year with both of my sons cars, two different items caused the problem.
After checking the filters, sensors and fuel pressure we found the fuel pump would quit after 15-45 minutes in the 83 car.
The DME computer once warm would give up in the 88 car.
Replaced the fuel pump and re-soldered one broken joint in the DME.

Fuel pump and DME are easy repairs. Do you have access to a known good DME?

Both running well now, good luck.

[Peter Burrowes]

unfortunately , I do not, wish I did. Perhaps I should try the local junk yards, this is one of the negatives of living in a rural area

[GreenWater]

All good advise. I would guess that it's not the coolant temp sensor. I had one go bad on me. The car would start up cold and run forever just fine. But if you turned it off after it's warmed up, the car just wouldn't start up again until it cooled off. The coolant temp sensor tells the DME what fuel/air mixture to give the engine. If it's broke it gets confused and gives the engine either too much or not enough fuel/air. So I don't think this is your problem. Just for fun, I started the car and then pulled the wires off the temp sensor and the car runs just fine.

But, like we all know, there's just no rules with it comes to 944 issues. Especially electrical ones.

I have considered burning my car, many time.(literally) But don't, just remember how much fun they are when they are running good.

Good Luck.

[Peter Burrowes]

LOL, only kidding on the burning but I have no idea on why Porsche made the electrical system so complicated, drives me nuts

[mueller944s2]

Originally Posted by Peter Burrowes

I often think to myself, considered burning it!

Can't tell you how many times it's crossed my mind.