I'm starting a new thread about this as my previous one went a little off base so i wanted to get this all down into one area.
Since i've had the car i've had occasionally starting problems and intermittent cutouts. Basically i turn the key and sometimes it will rev up to 1000 and then down to 300 and die. Sometimes the engine catches itself and brings the revs back up, but sometimes not. You can stop it with some gas. It also occasionally just dies when idling (at a junction for instance, or alternatively you can leave it in the garage ticking over and it will eventually die)
The fault code for any of these circumstances is (including it stops it from stalling by suddenly catching itself)
You can reset the code but it will come back when it does it next.
2D29 CDKPDDSS - Plausibility diff. pressure sensor, (FROM INPA)
Error counter: 1
Logistic counter: 40
Mileage 65560 km
Supply voltage (ub) 13.28 V
Engine speed (nmot) 240.00 /min
Engine temperature (tmot) 53.25 degrees C
Ambient pressure (pu) 1035.00 hPa
Unknown type of error
Test conditions fulfilled
Error present now, but not yet stored (debouncing phase)
Error would not cause a warning lamp to light up
So far this is what has been done:-
Indy:- Firstly noted it was a new sensor fitted in March just before i got it. He changed Timing chain guide, smoke tested manifold for leaks (none) has tested the sensor, the wiring and the ecu. All of which come up fine. He told me to take it to BMW as he basically thinks the whole thing is perfect and doesn't see why the code is coming up, he also checked the crank sensor and found it to be ok. The ccv was also checked and found to be in perfect shape.
BMW Sytner:- Magically found another error about the vvt servomotor and decided the "Plausibility diff. pressure sensor" was an offshoot of that. So i trusted them and they fit a new servomotor at a crazy price. It stalled almost as soon as i got out of the car park. They have done a free diagnosis for me after that and are now saying it "may" be the crank sensor (which checked out ok by the INDY. But i don't see why it would be pulling the pressure sensor code. And after their vvt servomotor episode i don't see any reason to trust them.
I'm at a massive loss with what to do now. Apart from perhaps finding another bmw indy. Is there anyway a small airleak wouldn't have been picked up in a smoke test? The indy to his credit had the manifold off more than once but couldn't find anything.
I've already sunk a lot of money into supposed fixes and there doesn't seem to be anyone who could figure this out.
Any thoughts would be greatly appreciated.