2008 2.7 PSM Failure-DME Fuse Blown

[billb]

Total shutdown at 60 mph and no restart. Towed to dealer. Tech got a replacement fuse to blow, but after hooking up test equipment to identify short, engine restarted and they can't make it fail since. They've had it for a couple of weeks now and I told them to drive it until it fails again. Tech thinks it will eventually, and then plans to work backward from the various sensors on the DME circuit. Does this sound like a reasonable approach? I don't need the car right away, but don't want it to shut down as I pull out into traffic. Dealer says no bulletins on same problem and I have no reason to suspect otherwise, but would like to get all the help on this I can. I'm in Portland, Oregon area.

Bill

Oh, and no codes.

[Loren]

:welcome:

Have them check the crankshaft position sensor. Sometime they open and close when they go bad. It is like someone turned off the fuel pump because no signal from the sensor tells the DME (and fuel pump) to stop sending spark or fuel - the engine is not running.

[billb]

Thanks for the quick reply. I passed it on to the service manager - he wasn't totally convinced - thought there should have been a code thrown off - but was appreciative of any ideas. I'll let you know how it turns out. Bill

[Loren]

I've seen an intermittent CPS fail to throw a code - you have to catch it in the act.

Something else to check since the DME fuse blew - have them check to see that the DME connector is tight. I've seen a loose connector cause similar problems too.

[billb]

Still no solution from the dealer or Porsche national, though the car is running fine with no codes. I'm wary of picking it up until they find a cause. Any other ideas? All connections were checked, sensors actuated, etc. Factory service told them to check the cooling fan, but all was good there as well. I still have plenty of warranty left but don't need to get stranded again. I read somewhere about DME relays causing problems in Porsches - could this blow a fuse? Should I ask them to just start replacing parts? We're all stumped. By the way, I have no complaints about the customer service. Bill

[Loren]

You only have 1 DME relay (position 11 on relay support 2). I doubt it is the problem - in my experience relays either work or they don't.

[billb]

Still no smoking gun. Porsche factory tech had the dealer inspect the DME wiring harness inch by inch and connectors. No damage at all. No mice signs, nothing. Now they are going to replace the DME. Happy it's winter and haven't missed any top down weather. I certainly hope this is the fix.