[BMPILL]

2013 model / 22k mileage only. Car jerks on acceleration except when traction control is off. Not fuel. No messages on BMW diagnostics test. Obviously a link to power on & traction control on. Any ideas very welcome!

[No one]

If it's all right with traction control off then that's it - keep it off! Actually traction control should confirm it's intervention with the instrument indicator flashing. What about your tires condition - can they just slip these days (already)?

[eray]

could be brake system related issue. maybe it's the abs sensors failing to detect slippage properly

[BMPILL]

Thanks for ideas. Not tyres as all good. Not sensors / perforated rings not blocked or corroded either. Seals OK. Traction light working if actioned. Pain of a problem. Wondered if there is a link between throttle & traction control?

[ovekvam]

It could be a tyre circumference issue. The car will register that some wheels are rotating faster than others, and throttle back to avoid what it thinks is slipping.

[No one]

Originally Posted by ovekvam

It could be a tyre circumference issue. The car will register that some wheels are rotating faster than others, and throttle back to avoid what it thinks is slipping.

Simply put: "Check the tyre pressure"?

[ovekvam]

Originally Posted by No one

Simply put: "Check the tyre pressure"?

Tyre wear and tyre dimensions could be additional factors.

[No one]

Originally Posted by ovekvam

Tyre wear and tyre dimensions could be additional factors.

Sure. I just meant you had omitted a possible solution.

[BMPILL]

Thanks for input. Yes it could be the wheel radius / tyres but all tyres all OK with pressures per BM's recommendation. We did have all tyres with a higher psi to protect the shoulders (all are run flats) for a while, but this seems to make no difference. But I still wonder if there is some mechanism that links the accelerator to the traction control?

[ovekvam]

Originally Posted by BMPILL

But I still wonder if there is some mechanism that links the accelerator to the traction control?

They are linked in software.

[BMPILL]

Could fault lie with the clutch control valve? Seems a part under suspicion!

[No one]

If your clutch does not close you should smell it under acceleration. The tachometer pin should go faster than the speedometer one as well. If you mean it might take time to close actually - give it some time and then try to reproduce your issue.

And by the way: clutch failure would actually affect it causing wheelspin - you should just hear it then (I do sometimes when shifting up to the 2nd or even 3rd(?) - people might think I have some power )!