Crank No Start

[DuhSoDeadly]

Good afternoon,

I have been banging my head against the wall trying to figure this out.
I have a 2000 Boxster 2.7 L that just hit 100k miles.
It had a rough idle and misfire for a little bit so I replaced the spark plugs and coil packs.
That didn't fix it so then I had a smoke test done on the intake and didn't find anything obvious; tightened all connections just to be sure.
Eventually the car had no acceleration; and shut off on the highway.
Restarted the car, it ran for a few seconds, then shut off.
Eventually would not start.
Towed it to a mechanic and they said my fuel pump was bad; replaced fuel pump.
Still have crank no start.
Tested fuel pump connector, no power to the fuel pump.
Tested fuel pump fuse, 12 volts.
Tested fuel pump relay, junction 85 and 86 not getting signal to turn on.
Purchased bypass relay, pump turns on but still crank no start.
Thought maybe my fuel filter, but that wouldn't cause 85 and 86 to not turn on, right?
Searched forums and someone said immobilizer, but upon further research if the immobilizer was bad then my car wouldn't even crank? (Not sure if this is true or not)
ChatGPT says it could be my DME?
At this point, diagnosing this car is getting to be a bit more than what I can handle.
Another mechanic that specializes in Porsche's says it sounds like independent issues; one causing a rough idle, and another that's causing the crank no start.

Anyone have any guesses or corrections to my assumptions?

[JFP in PA]

More likely the crank position sensor; when they fail, the DME does not see the engine rotating and shuts the fuel pump off as safety feature.

[DuhSoDeadly]

I bought a new Crankshaft Position Sensor, the labor looks easy from what I can see on YouTube. Jack the car up, take off the rear passenger wheel, and then replace the sensor. Might be a bit difficult to replace due to the sensor being in a hard to reach place, but the procedure itself seems quick and painless.

Thanks again for the response.

[DuhSoDeadly]

UPDATE:

I replaced the crankshaft position sensor, no luck. Something to note is that the key fob hasn't worked since I bought the car, the light would come on but would not actually do anything. The car was still drivable and I didn't need to use the key fob buttons so I never addressed it.

I noticed that the light on my key was no longer illuminating when pressing the key; so I replaced the battery. The light comes on now, but still doesn't actually do anything for my car.

I tried numerous different reset procedures. Hold the unlock button on the key, hold the button on the key while the key is in the ignition in the "ON" position, try locking and unlocking the car manually with the key, unlock and lock the car numerous times manually whilst holding the unlock button, reverse the battery polarity then press the unlock button for 60 seconds, etc. etc. etc.

Is there an actual, verified method for resyncing the key to the immobilizer? Seems like everyone is just taking shots in the dark as to how to actually resync the key.

Nothing is happening, the buttons still do nothing for my car and my car still doesn't start.

At this point, I just don't know what to do. I tried replacing the Fuel Pump, I tried replacing the Crankshaft Position Sensor, the car has new coils and spark plugs, the only thing that could possibly be causing me issues now is the immobilizer but the car still turns over and I don't have an immobilizer light on my dash so IDK.

S.O.S. please someone help me get my car back.

[JFP in PA]

As the car will crank, but not start, if the immobilizer is bad, it looks like time to start looking there............

[DuhSoDeadly]

Originally Posted by JFP in PA

As the car will crank, but not start, if the immobilizer is bad, it looks like time to start looking there............

So I got popped open my immobilizer case to check for corrosion; to my surprise it looks brand new. Everything appears to be in mint condition.

How would I go about conducting further testing? Is there a way for me to know that the immobilizer is telling the car to not start?

[JFP in PA]

For that you need a PIWIS system to test it, but it needs to be in the car for that; otherwise you need to send it out to someone that can bench test it.

[BOOTLEG]

I too have crank but no start on my '02 S. Because the tach needle moves to ~1K, is it true I can eliminate the crank sensor as the problem?

[JFP in PA]

Originally Posted by BOOTLEG

I too have crank but no start on my '02 S. Because the tach needle moves to ~1K, is it true I can eliminate the crank sensor as the problem?

Probably.

[DuhSoDeadly]

Originally Posted by JFP in PA

For that you need a PIWIS system to test it, but it needs to be in the car for that; otherwise you need to send it out to someone that can bench test it.

Is there a technical diagram of the immobilizer?

Basically I'm assuming that if the logic strings don't match up between the immobilizer and the key then the immobilizer sends a signal to various parts of the car preventing them from operating. I would like to take my multimeter and test if I'm getting an electrical signal from my immobilizer, (or perhaps even a lack of signal that SHOULD be there) thus preventing the car from starting. The immobilizer is complex, but it's not magic; I should be able to test it myself with a multimeter, I just don't know what or where I need to test on it.

Thank you.

[JFP in PA]

As it is part of the car's security system, Porsche never published it.

[DuhSoDeadly]

So I ordered an OBD2 scanner and checked for codes, currently not showing any codes but I did have the battery disconnected on multiple occasions since it hasn't been running. With that being said: Would I still be able to see codes when scanning, or are they going to be temporarily cleared until the car is running for a bit? If it is the case that my car did store a code, but disconnecting the battery has cleared it, is it possible to retrieve that code or have it reappear in a vehicle that won't start?

[JFP in PA]

Originally Posted by DuhSoDeadly

So I ordered an OBD2 scanner and checked for codes, currently not showing any codes but I did have the battery disconnected on multiple occasions since it hasn't been running. With that being said: Would I still be able to see codes when scanning, or are they going to be temporarily cleared until the car is running for a bit? If it is the case that my car did store a code, but disconnecting the battery has cleared it, is it possible to retrieve that code or have it reappear in a vehicle that won't start?

If you previously disconnected the battery, you probably erased any stored or pending codes. This is why we tell people to never try and clear codes by disconnecting the battery, you lose all the diagnostic data that was stored in the DME and have no idea where to begin...........

[DuhSoDeadly]

Originally Posted by JFP in PA

If you previously disconnected the battery, you probably erased any stored or pending codes. This is why we tell people to never try and clear codes by disconnecting the battery, you lose all the diagnostic data that was stored in the DME and have no idea where to begin...........

It was never my intention to clear codes; unfortunately just about every repair or maintenance task requires the battery to be unplugged. The car is going to a local European exotic specialist on Wednesday so hopefully they can figure out what's going on with it.

[JFP in PA]

Originally Posted by DuhSoDeadly

It was never my intention to clear codes; unfortunately just about every repair or maintenance task requires the battery to be unplugged. The car is going to a local European exotic specialist on Wednesday so hopefully they can figure out what's going on with it.

Message was to always scan the car before disconnecting the battery and writing down all the codes so you have something to work off of after the data is lost............

[j101248]

Any update on the crank no start issue?