89PorscheTurboMobile

Hello, weird problem in my 951.
After I finish driving the car for around 20 minutes, I park the car, go to class, and come back in about 4 hours. When I try and start it, all it does is crank, and crank, and crank. What I have to do to get it to start is disconnect the negative battery terminal, and reconnect it. Then, when I try to start it, it fires right up..

Any ideas???

cruise98

Clean the battery terminals and ground connections first, then try a new DME relay. The grounds are to the body in the battery box, and the two on the rear of the engine. There are others, but they run other circuits.

Peckster

If it cranks ok the battery connections are fine.

rhesus

I wonder if the rain is affecting your DME somehow, and disconnecting the battery resets something....
Is it all dry under there?

PorscheDoc

Is your tach bouncing when you are cranking? Pulling the negative cable, could have been enough movement to bump one of the reference sensor wires enough to start.

89PorscheTurboMobile

Battery terminals are very clean.
DME/KLR computers are dry.
The tach does bounce while cranking.

Bri Bro

Maybe the alarm system. The DME is powered down when the key is off. Karl point is well taken, when it is running, try wiggling the wires around the battery area and see if it quits.

ed devinney

I had an alarm on my car which was installed with scotchlocks which damage the wiring. It's still not 100%, but removing it helped a lot. Every once in a while now my car needs to have the wires to the reference sensors (rear of the intake) jiggled and it starts right up.

cruise98

Peckster: Not necessarily. The grounds for the DME system are independent of the battery cable. I was going for the loose connection/dirty grounds theory first. It is free!

89PorscheTurboMobile

OK,

My problem has returned.
Today when I attempted to turn the car on, it just cranked and cranked, like before.
Well, I know that pulling the negative and putting it back will make it start, so I decided to experiment, and pulled each fuse and relay 1 by 1, until the car started.
I went through ALL of them, and the car still didnt fire.
But, as soon as I disconnect the negative, and reconnect it, it fires right up.
And when I shut it off, and try and start it again, all it does is crank and crank, like before.
I've tried wigging the speed/ref. sensors, but the car didnt fire.
I've also tried swapping DME relays, but it still does NOT fire.

What the hell is wrong with it?

faithless

I've heard of this problem before... I know it!

89PorscheTurboMobile

Trying to build up your post count?
What is it?

faithless

Wow... I'll remember to ignore your pleas for help from now on.

Bri Bro

Did you check the alarm system?

89PorscheTurboMobile

Hi Brian,

Yes I have, I disconnected the fuses, and even went as far as pulling the power bundle out of the alarm brain by the DME.