Hawkaloogie

Hi everyone, need a little assistance.
I'm a tech at a shop that specializes in Porsche, but this has us all at a loss, so I'm here humbling asking for any assistance in the right direction.

The car starts only if the battery is disconnected for some time. Other than that, the car doesn’t even crank.
DME has been replaced
PAS has been replaced
Starter has been replaced
Ignition switch has been replaced
Clutch switch has been bypassed
Battery is new, both in car and key fob
All ground cables are good
Gateway is good
Additionally: When the car is on, the DME reads. But if it isn’t on, then PIWIS can’t communicate with it.
Thank you in advance for any help. If there is already a thread on this and I didn't find it, I'm sorry for starting a new one.

snaphappy

There are much smarter people on here, but I’d put in a different battery, just to see what happens. Another guy recently had a similar problem - literally brand new battery - and the car wouldn’t start. His new battery turned out to be a dud.

Hawkaloogie

We have it on a battery charger set on flash mode during programming. I would assume the charger voltage would override the faulty battery. But I'm at a loss and we do have extra batteries in the shop, so i'll give it a shot.

BaileyII

I had to replace my voltage regulator on mine last year. I do not know if this related.

aaks38

the battery charger simply cant compensate for a bad battery assuming it is a bad battery. The battery is a source of instantaneous charge/currrent which simply no battery charger cant substitute, the battery charger can at best source 7-10AH, whereas your battery does more along 800-900CCA under an instantaneous condition during starting. I think for starters you need to ensure you have a good battery with good cable connections all the way through the starter and to ensure the starter motor is getting a 12v signal under cranking as well as the normal 12v high current feed from the battery.

If these are good, maybe look at crank/cam position sensors, ignition wires and the wire harness which leads to the coil packs. Hopefully your ECU/DME are flashed correctly and known to be working.

Spiffyjiff

it's not a hurricane / flood car is it? if so, all bets are off - the elec gremlin could be anywhere...