Intermittent starting issue

[SaltWater]

1999 Carrera4. 5 years I have chased this intermittent problem. Sometimes the car refuses to start. Starter will not turn over. All maintainance has been done at a dealer service center. They say they've never seen this issue before. It's not DME they say. Every component from entire key system to the starter, as part of the security system/start permission, has been replaced. Car can go for months with no issue, start every time, then it's like a gremlin grabs it and it will not start. No error code(s) reported. Everything appears normal and proper with dash lights. Might be a minute, an hour, a day, a week... and it starts. You never know if it will start or not. 

Possible weak point in the wiring? Software issue? I'm flying blind on this.

Has anyone experienced anything like this? 

[Uwon]

The ignition key module on my 997.1 acted as you described. I think it is the same for your car. A quick DIY replacement corrected it, but then again, this particular problem is well known so you may have already done it.

good luck

Johan

 

 

[SaltWater]

Thanks, Uwon. 

Yes, that module has been replaced, along with every other module, incl clutch micro-switch, affecting the starting of the car. Gremlin still there. Last thing that was done, 2 weeks ago, was the cam positioning sensor. 

Last night tried to start it. Spent 40 minutes trying to start it. No go. This morning tried again. 30 minutes. Ready to quit. Okay, one more... and it started. It's infuriating. 

I'm finding it hard to think it's a cable connection given it may start no problem for months. This car is a nightmare.

[DBJoe996]

I take it that trying to start it, it cranks but does not fire? Is that correct?  Or does it not crank?  Cranks but no fire is caused by the CPS - crank position sensor.  Does the tach needle bounce when you try to start it?

 

If no crank - ignition switch, bad starter, corroded Y-cable, clean all engine grounds

[SaltWater]

As OP says, starter does not turn over. The car is like it's ready to start, all proper dash lights on, waiting for the key to be turned. It starts when it wants to... or not. 

This car has been gone over for 5 years by the prof. service techs at the Porsche Service Center. Cables, grounds all appear okay. They don't have a clue why it does this. And being intermittent makes it a bear. The car may go months without this issue. Then it rears it's ugly head and the refuses to start... till it wants to. 

Every component from the key assembly to and including starter has been replaced. It left me high and dry overnight last week. It may be first throw of the key and it starts to repetitive throws over time. Yesterday it started on the 11th when I left and the 2nd when I headed home. 

[Loren]

If this is a manual transmission car - have you checked the clutch switch?

I had a similar issue and it was an intermittent clutch switch.

[SaltWater]

Ah, yes. 

[Down South]

Saltwater, did you ever find the issue? I'm having a similar problem.