Audi Cabriolet 2.6 Stalling after 2-3 seconds

[Jaco Mostert]

Good day everyone,

I've got a 1996 Cabriolet 2.6 which starts up perfectly, runs for 2-3 seconds and stalls.

TLDR - I think it is the immobilizer or ECU

Things that might help:
- The engine starts up perfectly almost every time, the just dies after a few seconds.
- I replaced the head gaskets recently and the car drove perfectly after that.
- The car does not drive too often, but I try and start it up at least once every 2 weeks.
- The problem started only when the engine was hot, but now it does not matter.
- Using VCDS (Vag com) to check there are no fault codes, but I can't connect to the engine module. I could do this previously.
- I need to replace the air-con pump as the clutch is not engaging.
- I sat on the rear lid for the top fixing the rear window.
- The car ran perfectly last week.
- The car has a battery cut of switch, which I use.
- The car has a problem with the battery draining quickly (within a week or 2 if left connected.) The battery is still good as it is fairly new.
- The key is worn, but the light in the dash goes out when turning the key.

What I've tried so far:
- Checked the fuel pressure regulator (seems to be working.)
- Checked the cam sensor (when I disconnect it the car doesn't start at all.)
- The fuel pump primes perfectly and the relay seems to be working.
- All the fuses look good.
- Found the ECU (behind the glove box), unplugged the connectors and put them back. (It seems like someone has fiddled here previously, but I've had the car for 4 years now.)

What I suspect:
- I've had problems on my A6 2.6 before with the fuel pressure regulator, cam sensor and crank sensor before and the symptoms were different so I don't think it is those.
- I think it has something to do with the immobilizer or the ECU, but I'm not sure how to confirm this. (My biggest indicator is the engine module not being available.)

VCDS/Vag com

Thursday,09,April,2020,12:56:36:40899
VCDS -- Windows Based VAG/VAS Emulator Running on Windows 10 x64
VCDS Version: 19.6.2.0 (x64)
Data version: 20190930 DS308.0
www.Ross-Tech.com


Mileage: Repair Order: Cabriolet



--------------------------------------------------------------------------------
--------------------------------------------------------------------------------


Chassis Type: 8G - Audi Cabrio B4 (1992 > 2000)
Scan: 25 01 02 03 08 15 26 35

-------------------------------------------------------------------------------
Address 02: Auto Trans Labels: 01N-927-733.lbl
Part No: 01N 927 733 AP
Component: AG4 Getriebe 01N 2850
Coding: 00000
Shop #: WSC 00000
VCID: 7F0BBB767D62BFB7DE-095C

No fault code found.

-------------------------------------------------------------------------------
Address 03: ABS Brakes Labels: 4A0-907-379.lbl
Part No: 4A0 907 379 A
Component: Bremsen-Elektronik
Shop #: BB 33837
VCID: 295F452ED366E107D0-4AE6

No fault code found.

-------------------------------------------------------------------------------
Address 08: Auto HVAC Labels: 4A0-919-579.lbl
Part No: 4A0 919 579 F
Component: Stg. Klimak. 6-Zyl. D07
VCID: 3363A74601AAABD76A-2012

1 Fault Found:
00532 - Supply Voltage B+
07-00 - Signal too Low

-------------------------------------------------------------------------------
Address 15: Airbags Labels: 8A0-959-655.lbl
Part No: 8A0 959 655 B
Component: Airbag V AUDI D00
Coding: 00766
Shop #: WSC 01670
VCID: 326DA242FEB0A2DF61-5120

No fault code found.

-------------------------------------------------------------------------------
Address 26: Auto Roof Labels: 8G0-959-255.lbl
Part No: 8G0 959 255
VCID: 72ED62423E30E2DFA1-4B32

No fault code found.

End-------------------------(Elapsed Time: 01:42)--------------------------