Hello,

We have just taken delivery of a Tourneo custom that has auto start stop. This is the first time I have driven with this technology and while I didn't have a problem with it and it behaved as expected when I was driving, my wife had an issue with it.

She was going round a corner that was third gear on entry but required second on exit. She pressed the clutch and moved the gear stick into second but didn't not release the clutch again. Halfway round the corner the engine turned off, of  course this the knocked out the power steering.

If we ignore the bad practise of coasting round the corner I'm just wondering why the engine turned off? While I was driving the engine only turned off when I stopped, went into neutral then released the clutch again, she still had the clutch pressed in. Also, do these systems not have a sensor that detects the car is still moving so doesn't turn the engine off. I have read that some systems will detect when the engine is at idle speed (which it would have been halfway round the corner) and the brake pedal is pressed and that will turn the engine off, is this true? 

I have told her she'll have to be in the correct gear before making the manoeuvre in future so we're not here to comment on that, my issue is the engine turning off while the car is still moving and what caused it to as that seems to me to be a major safety floor.

I know you can disable the auto start stop and for all I know it could have turned off for another reason as I couldn't see the dash display at the time but I cant think of any other reason that it would turn off, it definitely wasnt a stall as the clutch was pressed.

Thanks

Start stop doesn't kick in until the car is in neutral AND the clutch pedal is released for just that reason.
Sounds more like a stall than stop start activating.
Fyi, if you have stop start then you should also have stall recovery, if you stall then just press the clutch pedal and the engine should restart.

Sent from my SM-G965F (S9+)

2 hours ago, Robotsindisguise said:

She pressed the clutch and moved the gear stick into second but didn't not release the clutch again. Halfway round the corner the engine turned off, of  course this the knocked out the power steering.

I would say it was either driver error or there is an unusual fault in the car.

It could be she went into 4th instead of 2nd (i have done that a few times), then releasing the clutch at low speed would stall the engine.

Otherwise it is possible the engine stalled due to some fault like an air bubble in the fuel, or some electrical glitch.

I am sure that the software will not allow auto stop to happen with the clutch pressed and the car moving. If the ABS is functioning ok with no warning light on, then the wheel speed sensors etc must be working. Many drivers, especially older ones like me, often coast in neutral for awhile, while deciding what gear to engage next, depending on traffic ahead. I know it is not recommended on power steering cars, due to the reason you give, but for safety reasons the stop-start system will be designed and tested to cope with such foibles.

I would try to repeat the events, under safe conditions, to verify if there is some fault.