bbri4570

So I was heading into work this morning, loving my 30 mile commute for the first time in years thanks to the joy of driving my (new to me) '84 944. The stoplight turned green, I eased into first, accelerated about 1/2 throttle due to traffic, easy shift into second, back on the throttle and about 4000 rpm she just died . . . no sputter, no cough . . . just dead. Coasting, I started pulling over to the shoulder, noticed my turn signal not working, hit the hazards and nothing . . . no juice at all. Just like someone disconnected my battery? I got her over on the shoulder, turned the key - nothing. Got under the hood - battery still connected ( start w/ basics ).
Got on the phone to my wife to come rescue me . . . while I was on hold I noticed the hazards were flashing? Back from the dead? Did I touch something under the hood? So, I jumped in and she fired right up, off we go. Got about 10 miles down the road, on the interstate now, 75-80 mph and she dies again . . . no warning, no sputter, dead. I hit the hazard button - nothing and coast downhill over to the shoulder. As I roll to a stop (20 seconds later) the hazards, radio, etc all come on, clutch in, turn the key, she fires right up and off we go. Made it the rest of the way to work w/ no further issues.
Now, where do I begin? Do I have a bad ground somewhere? Relay? Computer? What would make it act like I disconnected the battery (radio stations all reset on radio!) Please help

User 41221

Check your grounds.

Regards,

Yabo

Check grounds, then clean your battery terminals..... That's basically is all it could be. There's no "main fuse" like there is on some other cars in thse, so it couldn't be that shorting. It could also be a short anywhere in your electrics. Hopefully not,b ecause it could be something as little as a frayed wire under your dash somewhere.

Porsche-O-Phile

Grounds, battery connections, etc. Some cars have a "quick shutoff" on or near the battery for working on the engine (virtually anything requires disconnecting the battery unless you want to get your hand chopped off by the electric fans. . .) Maybe the PO installed one?

bbri4570

I will start with all the grounds and make sure my battery terminals are clean and let you know.

pete944

This is something I copied from an old post a few years ago:

Porsche 944 ground points:
-Front frame rail both left & right, M6x12
-Behind the battery in the fire wall, M8x35
-Bell housing, M8 stud
-Under dash, left side of steering column, 3-off(?) M6x12
-Under floorboard near DME, M6x12
-Rear, in trunk, below left taillight, M6x12
-Ground bus under the battery box. Accessed by lying on your back, feet up through the sunroof. If memory serves, there are 7 circuits grounded there, one of which is the instrument cluster. This bus is a common source of problems if the battery box has a leak since the water will corrode these grounds."

Tony K

On my 83, the positive cable corroded badly inside of the insulation from the connector to about 2 inches in. Take a look at the condition of the battery cables, feel if the positive one is getting hot. If it is, you have a lot of resistance because it is corroded internally. Get out your voltmeter . . . .

Good luck,

Peckster

If the batery terminals are clean enough to run the starter there's no way they'd cut out just running ignition. I'd have though the grounds are the same way. I wonder if something is shorting out somewhere. Look for a big wire touching something hot.

Tony K

Battery bolted down and covered?

Peckster, I read somewhere that heat increases resistance in an electrical circuit (no, not confusing it with resistance creating heat); resistance creates heat and heat adds to the resistance, kind of building each other up. That would explain the problem I had in my 83: My corroded cable resulted in the car's voltage dropping slowly over a multiple-hour trip. The + cable, near the terminal, got so hot that it melted the plastic battery cover and the voltage was low enough that the engine would cut out (presumable not enough voltage through DME relay). Headlights were dim, voltmeter low, the whole nine yards. When cooled back down, everything was fine again for a while...

But yeah, highly unlikely in this case what I said before. Good to check, though, just for the sake of covering all the bases.

Tony K

More current needed on the freeway? . . . . (coil firing more times per minute)

bbri4570

Just went out after work. She won't start, just cranks. Tomorrow I will dig into the batt cables, grounds and other possibilities. Taking a loaner home. Will update tomorrow.

Peckster

Take a dme relay.

Dilberto

Also check the crankshaft sensors...bet thats the real problem!

caster951

Same type of problem occurred on my 83 about a month ago. Turned out that one of the posts on the ignition coil was broken. This obviously caused an intermittent spark, car died, then fine...........replaced coil and good as new. Good luck tracking it down........

bbri4570

I will be in the shop all day tomorrow as I have not had any free time yet. I just noticed a burned spot between two wires that attach to the main battery cable, insulation had worn through. I will start there and work through all the suggestions. Thanks.