deane.barker

1999 996 Carrera (non-S, non-turbo, just...normal)

About a year ago, I started getting a "delayed start" when the car was cold. I would start turning the key, all the lights would come on and everything would be normal, but when I turned it all the way to start it, nothing would happen for 2-3 seconds. Then it would start normally. Not a slow crank or anything -- just a weird delay when I turned the key. This would only happen when the engine was cold and was more pronounced when the weather got cold.

And then, one day, it didn't start at all. The car would turn on, but you'd turn the key and...nothing.

I do not have a Porsche dealer in my town. The local VW dealer has a Porsche-friendly mechanic who has worked on the car before. He investigated it for two hours and determined:

• It's not the battery (that's about a year old)
• It's not the starter (that's less than a year old)
• It's not the ignition switch
• It's not the clutch engagement switch

In fact, they manually triggered the starter (basically forcing the engine to turn over). It would turn over, but would not start.

Something has...immobilized the car.

Again, there is no Porsche dealer in Sioux Falls. I'm looking at three hours on a flatbed to Porsche of Omaha, at this point.

Is there anything left to try?

DBJoe996

The car is not immobilized as it would be if the immobilizer kicked in and prevented the car from starting. One thing to do is check the voltage drop from the battery all the way back to the starter. You should have 13+V at the battery and the same at the jumper point in the engine bay. The Y-cable comes to mind. Perhaps it has corroded like so many have. Also would check the ground wire on the engine to the frame (behind passenger side wheel). Disassemble, clean any corrosion and reconnect. Another thing that sometimes helps, disconnect the two engine wiring connectors in the engine bay and liberally spray electrical cleaner on the contacts.

Has the ignition switch electrical portion ever been replaced? How did he determine to rule out the ignition switch? Also, starter replaced....was it replaced with a new Bosch unit or a re-manned starter? I chose a re-manned starter the first time and it crapped out within a year. So I put in a new Bosch starter and all good.

deane.barker

Thank you for this.

Even knowing that, you still think it might be cabling?

DBJoe996

Yes. There are a lot of things that have to happen in sequence to get a car to start. Obviously first is a healthy battery. Should be 13+V. Then the cabling for that goes to the power distribution box located inside on the firewall on passenger side. That powers up the system. A battery cable runs from there to a connection point under the car, then to the jumper point box in the engine bay. This supplies the high amperage/voltage necessary for the starter to run, so it needs to be 13V at that point. Then the high amperage/voltage cable runs through what is referred to as the Y-cable, which connects to the starter and alternator. That is the main high amperage/voltage circuit.
From the power distribution box, lower amperage/voltage goes to the relay and fuse boxes. There is a starter circuit relay in Relay Support Group 2. It could be that relay that is causing a delay, or has now failed completely. 12V is supplied to the ignition switch, then when turned to start, 12V is sent to the starter relay and that kicks the starter solenoid in so the high amperage/voltage is supplied to the starter to turn the engine over.
Power Distribution (those are 80 amp fusible links and can blow)

Relay Support (underneath rear shelf carpet)

islaTurbine

The member Ahsai has a great troubleshooting writeup for the starter-alternator cable. It's a good place to start and always a likely culprit for anything start related.

Ahsai

Ok, will try to help here. OP, have you checked inside the key fob and see if the transponder pill is secured? Tried another key?
Checked fuses C1-C4 and E1. Any CEL?

I take the current symptom is: turn key to crank and nothing happens even with the clutch switch jumped?

If so, it will be very easy for the shop to check two things: 1) If the start lock relay gets power when the key is turned to the cranking position (yellow paths here) 2) If the start lock relay is activated by the DME when the clutch is pressed all the way.

If 1, ignition key is the issue.

If 2, you need to check the wires between the DME and the relay. If not that, the DME is not picking up the transponder on the key somehow.

AWDGuy

Check yout Crankshaft position switch on the back of the motor.

DBJoe996

I agree that the CPS should be checked if the situation is the engine turns over but will not start. His situation I believe is the car won't even turn the starter motor over. So something is amiss in the key/immobilizer/starting circuit because the engine won't crank at all..

deane.barker

What does this mean, exactly? The key does light when pressed, and it does lock/unlock the car, so I know it has power and is functional.

Ahsai

​​​​​​Those are totally seperate functions. The pill is embedded inside the key fob and it does not even require a battery to operate. It's activated (wirelessly) when the key is inserted into the ignition. The DME needs to detect that (and the clutch microswitch closed) before activating the start lock relay and the fuel pump.

Ahsai

I take that now the starter doesn't even turn? Or it turns but the engine doesn't fire up?

deane.barker

Weirdly, both are true.

1. The engine will not turn over for me, sitting in the driver's seat, turning the key.
2. However, the shop manually triggered the starter (I do not know how they did this). The engine would turn over then but still would not start.

DBJoe996

A person can hot wire a starter by simply hooking up a 12V lead to the starter solenoid. If the starter has the 12V main connected, that will make the engine turn over, but it bypasses all the other circuitry necessary for the engine to run. I wonder why the shop has not checked the start relay as I previously suggested. Somewhere along the line something is not lining up in all the steps needed to start..key, immobilizer, starting circuit, and so on.

deane.barker

To be fair, I might be hopelessly misrepresenting what the shop has done so far. And I haven't shown them this thread just yet, so they haven't had a chance to take any actions based on it.

Ahsai

Based on your description, I can only eliminate the starter itself as a problem but even that depends on where it was hot wired by the shop. As Joe said, there are a lot of things need to line up first before the starter will get power:

Current path: Battery->battery cable->ignition switch->start lock relay->starter solenoid. Control path: key transponder->clutch microswitch->DME->start lock relay

If the starter spins but the engine doesn't fire up, that's a totally different problem, which requires checking of the crank position sensor, fuel pump, fuel pump relay, ignition, etc.