Intermittent issue when shifting gears - 130i Manual

[NZ_InFerno 371]

Got a 2006 Manual 130i with the following issue:

When changing gear, mostly from a cold start, and shifting into second, the accelerator totally stops responding. It doesn't rev at all or accelerate. It has also cut out on other occasions on the motorway at 100kmh between 5th/6th which is super sketchy ?. Have been smashing the accelerator and no response on a few occasions.

 I've been driving it every day to work out this issue. If I turn the car off and on again, after it happens, its fine and can drive it for a half hour or more with no issues and it doesn't pop back up. 

Today it happened again, and popping the clutch in and out the accelerator came back so seems like something going on with the clutch or gearbox.  Previously when it's happened I've changed gears but still had no accelerator response. Just sits at 1000 rpm in 2nd or higher rpms in higher gears.

It seems very odd that it kills the accelerator totally though, any ideas what the fault or cause could be? 

[M3AN 4016]

Do the rev's just drop to idle when it happens?

I realise you believe it may be the clutch/gearbox side but it would still be worth removing the accelerator peddle and check/clean/test the fly-by-wire cable/plug. It's easy to do and might show something up.

 

[NZ_InFerno 371]

Yeah they drop to idle or in-gear equivalent. 

Something I had been looking at was pulling it out and checking the sensor. I had priced up a replacement pedal or sensor too which isn't too bad. 

Just wanting to see if anyone has come across a similar fault and can point me in the right direction or cause, as I'm not really sure what it could be ?‍♂️

[KwS 2425]

Right, so I went over and had a poke around last night. Can confirm the issue, the throttle will randomly fail to respond immediately, and will come back with a jerk. After that if you keep driving there is no low end power and the throttle response is rubbish. 

Inpa comes up with code 2A38, valvetronic servomotor: binding or open circuit. No CEL. 

We cleared the code, did a relearn for both end stops (which passed OK, can hear motor go from stop to stop) and it seemed to drive fine until it faulted and threw the same code. 

At this point we noted in inpa that the live data from the valvetronic motor showed a fixed reading for "VVT actual value" and wasn't moving (like it does when tested straight after an end stop test). Running the end stop test again "freed" it up and it passed fine. 

So I'm thinking either it's the valvetronic motor, or maybe the eccentric shaft sensor. 

Need Dan to check if there is oil in the connector for the sensor as that's a common failure and oil is a giveaway. Neither part is cheap enough to be shotgunning parts at it. 

Anyone had this before? 

Edited March 9, 2020 by KwS

[NZ_InFerno 371]

Big thanks to KwS for coming round and doing quite a few tests, narrows down the faulting components considerably. 

Edited March 9, 2020 by NZ_InFerno