Random starting problems

[extanker]

if the starter motor is turning the engine over its not the clutch switch. check for spark and/or fuel

[spgribben007]

Thanks for the suggestion but without testing equipment how do I test for spark and/or fuel?

[binaryc]

Just got the car back from the shop. The problem was apparently pretty difficult to track down, but wound up being a weak/worn out engine speed sensor (part number 986.606.112.02).

[extanker]

crankshaft position sensor ?

[Pianohawk]

Originally Posted by binaryc

Just got the car back from the shop. The problem was apparently pretty difficult to track down, but wound up being a weak/worn out engine speed sensor (part number 986.606.112.02).

I've had this SAME issue for about a year and a half now. Money has been tight so I haven't taken it to the dealer yet (ind. shops haven't been able to diagnose it).

Would you explaining a bit more about what the mechanic said or PM me if you have a few minutes sometime. Thank you!

[binaryc]

From what I can tell, that sensor tells the computer the speed of the crankshaft, which controls spark timing and fuel injection. In my particular case, the sensor was putting out a weak signal, which is really weak in starting conditions (low RPM, low battery). The problem was also heat related -- if the engine was cold, it worked fine. If the engine had been running for a while, it worked fine. If the engine had been running, then shut off and sat for about 20 minutes, it wouldn't work until the engine cooled down further.

The actual part is relatively cheap, and replacing it is fairly easy. The hard part in my case was figuring out what the problem was. The tech had to hook up a break out box to the DME in order to track down which sensor was flaking out.