[terrypin]

My F30 2012 328i Luxury Auto (13,500 miles) gave me some worrying behaviour this morning. To overtake I often switch from Comfort to Sport and floor the accelerator to minimise overtaking time. But after that 2-5 seconds, when I backed off the pedal I expected the revs to drop quickly as the gear automatically changed up, which I'm sure is the normal behaviour. Instead, the high revs were maintained for perhaps as long as 4 secs or so. That happened several times.

I also thought that the engine felt slightly rough/lumpy at low speed. maybe 1200-1600 rpm.

A couple of months ago, only weeks after buying the car (with a BMW FSH), I had a Drive Train failure, immediately after rather similar symptoms. It was 4 days before the dealer got the diagnosis right, and they changed the ECU (which I take to mean the Engine Control Unit).

Any thoughts or advice (as non-technical as possible) would be much appreciated please.

P.S: In case it's possibly relevant, I did use the paddles a bit during this trip, first time in weeks. Don't really see the point of them though - it was just curiosity.


--
Terry, East Grinstead, UK

[Buttons]

You may be better posting your questions in the UK section (time difference reasons, that's all)
One of the characteristics of Sport Mode is that the 'box holds the gear longer and keeps you in the revs so that you're on the money when you replant your foot....
What you're expecting the car to do (change up) is what it does in Comfort Mode

[crono06]

Holding the revs up high is completely normal after you've gassed it pretty aggressively. The car does this in anticipation that you may do it again, so it doesn't have to waste time switching gears and building boost in case you do.

[Professor///M]

You explain normal engine behavior in sport mode, sometimes, depending on the aggressiveness of the throttle, it will hold the revs much higher than usual. Tap the brake or gas and it will automatically shift for you, if you don't shift manually

[HighlandPete]

Originally Posted by terrypin

My F30 2012 328i Luxury Auto (13,500 miles) gave me some worrying behaviour this morning. To overtake I often switch from Comfort to Sport and floor the accelerator to minimise overtaking time. But after that 2-5 seconds, when I backed off the pedal I expected the revs to drop quickly as the gear automatically changed up, which I'm sure is the normal behaviour. Instead, the high revs were maintained for perhaps as long as 4 secs or so. That happened several times....

As others have said, it can be completely normal.

The adaptive transmission control takes the following into account: "Braking deceleration and automatic upshift", therefore can supress an up change.

This is how BMW describe it for other auto transmissions, still applies in the ZF 8-speed.

The intention to apply the brakes can often be anticipated from the accelerator pedal being rapidly released to the zero position. If such an action is detected, the upshift is suppressed for as long as the accelerator pedal is in the zero position and the vehicle is in overrun mode.

HighlandPete

[DantonIzzo]

I agree with the above posters -- what you are describing is completely normal. I suspect that you are just a little sensitive about it because of your earlier engine issue.

[terrypin]

Thanks a bunch all, that's reassuring!

And I suppose I could rationalise that slight 'roughness/lumpiness' too, because of my 15 years with my previous E36 (1996 328i SE Auto) whose straight six was very smooth, albeit 192 bhp versus this 4 cylinders' 247.

--
Terry, East Grinstead, UK

[Blubaron79]

Normal