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2015 981 Cayman S- track failure NO START - C3400 & C2800 Codes

4K views 9 replies 6 participants last post by  rmarchjr 
#1 ·
Hello all,

A few days ago at Limerock my 2015 Cayman S just stopped running and needed to be towed off track.

It will not start at all, makes no attempt to run but cranks fine- like it has no fuel or spark.

https://youtu.be/8NRvVo-Mzhw
Problem occurs @ 12:40 - I am on the gas, but the AIM is showing No throttle.

I have scanned w Durametric and got:
C3400 MAF Sensor 2 - G246 Signal too high - No signal communication
C2800 MAP/MAF throttle position correlation- value below lower limit

Opened the engine cover- the intake manifold looks good, all connectors to Throttle & MAP are in place and tight.
I don't have a PIWIZ and sometimes Durametric code are incorrect. 981's don't have a MAF sensor only a MAP sensor, which is on order and will be here tomorrow.
Has anyone had a similar problem? It would be nice to have it running to bring to my Indy. I had thought even if MAP failed the car should run roughly, and that only a crank position sensor failure would cause a no start. Any thoughts are appreciated.
 
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#2 ·
If the problem is the MAP sensor, the engine computer (DME) does not know how much air is ingested and may not inject fuel as it does not know how much to do so. I might pull the big connector off the DME and reseat it.

Barring that, I assume you checked the fuses. Do you hear the fuel pump prime when turning the ignition on?

V6
 
#4 ·
Had a gas peddle potentiometer failure on ours in '15'; would drive fine at the track, then no power. Brought it in, no restart--had it towed home.
My tech said it was a rare occurrence but they only went down that path by going through the Porsche service network data base of problems to find something similar.
Not saying your Indy won't find it, but if the car is under warranty it might not be a bad idea to try a dealer.
 
#6 ·
OK, I have tested all fuses - OK
I do not hear the fuel pump, but I never have so that's not abnormal, and it does seem like a fuel flow issue...

I have replaced the MAP sensor - No luck.
This car has 2 fuel pumps - Low pressure=in tank & High pressure(not sure but I think its driven off the engine)
Yes - throttle is drive by wire & I hear throttle butterfly clicking.

Unfortunately, the car is stripped and has a full cage so even though its under warranty the dealer will not cover anything, I'm thinking to drop it off and let the pros have a look.

My guess is failed in-tank fuel pump. I will update when I know, No starts are so rare these days.
Thank you all for the help, it is appreciated- Mike_inOH...great info, you may have called it. Should have some info in a few days.
 
#8 ·
QUICK UPDATE -

According my Porsche Superman - the failure is the CRANK POSITION SENSOR.
The car had fuel in the line and fuel pressure but the ECU did not know where the engine position so no spark.
Better no spark then spark at the wrong time I guess, part should be here in a day or so, hope to have my car back soon.
FYI - This sensor failure does not generate an ECU error code via PIWIS- which is really dumb - thanks Siemens.
 
#9 ·
Thanks for the update. I will definitely file this in my 'WTF - I think I just killed my car on the track' file. May need to make myself a sticky for this.
 
#10 ·
OK - NO KIDDING THIS TIME - ITS THE REAL UPDATE.

So they changed CAM Position, Crank Position sensors and she still would not start. They then began tracking down the grounds, (Point 15? I think) there is a ground wire under the rear trunk carpets, under the ECU, it came loose and that is what caused the engine to stop running and no start. No PIWIS ECU code.

Apparently every one of the numerous grounding wires are very important in the Alum/steel 981 chassis!!
 
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