Intermittant no start

Skytrooper · Skytrooper's Garage

Hey guys, my '83 944 just recently began having trouble...occasionally...starting. It usually was the first start of the day. I thought since it was cranking really good that I would check the fuel flow (30second test). That was fine. Next I checked for spark, that too was fine. The odd thing was that if you walked away for 5 minutes and came back and tried to start it again...it would fire right up. I figured that it might be a good time to replace the DME relay. This seemed to cure 95% of the no-starts. Unfortunately for me it has become more random. Last week alone it left me stranded for over an hour (after being driven) each time before it would finally start. This car is my DD so you can see where it is a significant problem. Could the DME itself be dying ?

kdjones2000 · kdjones2000's Garage

The solder joints in the DME could be the problem, as well as the connections for the Speed/Reference sensors.

Skytrooper · Skytrooper's Garage

I have a spare DME. I guess I will swap it out and see if it helps.

UomoBello · 07-27-2009, 11:36 AM

My car does that, there is no spark until you wiggle the reference sensor harnesses. Try that. Those connections get loose sometimes.

Outback Porsche · 07-27-2009, 03:27 PM

Quote:

Originally Posted by UomoBello

My car does that, there is no spark until you wiggle the reference sensor harnesses. Try that. Those connections get loose sometimes.

I had this same issue until I replaced the sensor wiring harness (from Lindsay Racing) and both sensors. Use the BMW sensors 12-14-1-708-619-M14, they are half the price.

ballysdad · 07-27-2009, 05:43 PM

+3 on the sensors and or connections

Crazy Horse · 07-27-2009, 06:18 PM

One more vote for sensors...They'll surprise you. All will be OK and then your car won't start. Testing info is on Clark's Garage website. It worked for me (a reference sensor)......

benny_benny · 07-27-2009, 09:39 PM

alittle OT but does the speed sensor go bad as offen as the reference, or is it better to replace both when one fails?

Outback Porsche · 07-27-2009, 09:57 PM

Quote:

Originally Posted by benny_benny

alittle OT but does the speed sensor go bad as offen as the reference, or is it better to replace both when one fails?

It'd be a pretty safe bet that if one connector is failing, the other one will be not far behind. They can be a PITA to get out - while your in there you may as well save yourself a headache latter and replace them both at the same time.

WestonP22 · 11:09 PM

Quote:

Originally Posted by UomoBello

My car does that, there is no spark until you wiggle the reference sensor harnesses. Try that. Those connections get loose sometimes.

My car has the same issue... Closer inspection revealed that there was some missing insulation and the wire was exposed. The car will not start, and the tach will not bounce while cranking, if the reference sensor is disconnected or inoperative. But once you get it started, it will not die if you unplug the reference sensor, and the tach will continue to work as well, but your ignition timing will be retarded a bit. The speed sensor, on the other hand, will kill the engine the very instant it loses its connection.