Car died while driving and now won't start or turn over

[swaff]

I was driving home tonight when all of a sudden all of the cluster lights went off and the engine died. Once stopped, I was unable to get the car to turn over at all.

Battery reads 12v with ignition on, I tried installing a new ignition switch, and I checked fuse 1 on the E row of the fuse box (terminal 86s). The lights all cut on fine, and I hear a little motor when I put in the ignition, then it stops when I turn it. The engine will not click or anything. No noise when trying to start it.

The other weird thing is that I get "link error" when I try to connect to the DME via my code reader. I also tried disconnecting the battery for a while. No luck.

What should I check that would both make it die whle driving and also make it not turn over when I engage the ignition? The clutch switch seems to be ok, but if that was bad, it wouldn't make the car go dead while driving would it?

Thank you for any help and suggestions.

Swaff

[Ahsai]

I would guess ignition switch based on the symptoms but you said even a new one doesn't help. First I hope the engine or other accessories on the belt is not seized but you can always hand spin it to verify. I would suggest the following:

- check fuses C1 to C4

- jump the clutch switch anyway. Put the car in neutral and try to crank.

- load test the battery. Can even try to jump start it using another car.

- with car in neutral, remove the starter relay and jump pins 30 and 87. Starter should spin.

- on the relay socket side, check voltage between pins 85 and 86 when you crank. Should see 12v or so. If you don't see 12v when cranking, either you have a wiring issue or the DME is not activating the relay, which points to the clutch switch or immobilizer.

- bench test the relay

[swaff]

Ahsai,

Ok so C1 was blown. When I replaced it, the car cranked for a few secs, then that fuse blew again. What should I trace to find what's making it blow?

Thanks for your help!

Swaff

[swaff]

P.S. I also smelled a burning smell for a short time after the fuse blew.

[Ahsai]

Good. That's some progress. C1 is 25A and it supplies power to lots of engine related components, e.g., the DME, a bunch of relays, the MAF, evap vent valves, camshaft solenoids, etc. Too many to list. It will take some patience to track down the problem. Let me know if you want to pursue.

Can you tell if the smell is inside the passenger compartment or it's somewhere from the engine?

[swaff]

Edit

Edited July 15, 2014 by swaff

[Ahsai]

There's a short or failed component somewhere on that circuit (obviously) and there are a few possibilities. The DME itself is also a suspect e.g., the smell could be from a burnt transistor that drive one of the cam solenoids (not uncommon on MkI 996s and boxsters). One needs to open up the DME to smell it and visually inspect it. There are also many other possibilites on that circuit that need to be eliminated one by one with educated guess.

If the engine was removed for the job, it could easily be some wires got pinched and shorted. If not, the IMS/clutch job itself shouldn't disturb electrical stuff though. There's only one rear backup light switch on the transmission itself. However, I think it's a good idea for the shop to look at your car anyway since all these problems poped out right after they touched it.

The P1123 & 1125 codes mean the engine is running rich. Need to check the fuel pressure and the MAF.

[swaff]

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Edited July 15, 2014 by swaff

[Ahsai]

Um, I have some reservation of their findings and "solutions". Throwing a fuse with a larger rating there and claimed the problem is solved is a no no and a bandage at best. It may lead to even more problems down the road.

If the cam deviation triggered a CEL (assuming the fault was active and the CEL was on when they checked it), I wonder how they fixed it by just measuring things and claimed everything is fine. Or the CEL was off and this was an old code? What was the exact code(s)?

Also 1123 and 1125 should not be caused by air leak.

Just curious, does this shop have a good reputation of engine diagnostic?

[Ahsai]

Btw, I would insist putting back the 25A fuse (spec'ed by Porsche) there for testing and would not accept the 30A fuse as a fix.

[swaff]

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Edited July 15, 2014 by swaff

[Ahsai]

The fact they put a larger rating fuse there already told me their diagnostic methodology, regardless of their reputation...