Naughty SMG gear box

[aggi]

The SMG on my 328 (E46) is ocassionally staying in a lower gear, it wont change up when taking foot of the go button. Its like when in D the box is behaing like its in S. If you put it in manual, change up then back to drive it sorts itsself out.

Anyone seen this behaviour before? Is it a sign of impending doom!

[rassi]

SMG on a 328i? Thought it only came on the 330i?

[aggi]

rassi said:

SMG on a 328i? Thought it only came on the 330i?

Could be my terminology I mean the auto box that allows you to drive like a manual, i.e. move the stick forward to go up a gear back to go down. If this isnt an SMG whats the correct BMW terminology for it, but more importantly has anys one seen this behaviour before?

[StuB]

I thought the box was sposed to 'learn' your driving style and adapt it's shift strategy accordingly. You might be being a bit heavy footed. Have you knocked the lever forward to attempt a manual upshift?

[rassi]

aggi said:

rassi said:

SMG on a 328i? Thought it only came on the 330i?

Could be my terminology I mean the auto box that allows you to drive like a manual, i.e. move the stick forward to go up a gear back to go down. If this isnt an SMG whats the correct BMW terminology for it, but more importantly has anys one seen this behaviour before?

You have a steptronic, not an SMG. Your problem may be that the gearbox is adaptive, and if it has picked up on your driving style, which it may interpret as inconsistent or confusing (no offense!), it could be the problem. Try resetting it, IIRC, by disconnecting the battery for 30 minutes, and then drive it again.

[Egbert Nobacon]

aggi said:

The SMG on my 328 (E46) is ocassionally staying in a lower gear, it wont change up when taking foot of the go button. Its like when in D the box is behaing like its in S. If you put it in manual, change up then back to drive it sorts itsself out.

Anyone seen this behaviour before? Is it a sign of impending doom!

If its a steptronic ( as a later poster has implied ) are your tyres worn ?

Sounds daft I know but my E39 had similar and was advised to replace worn tyres - hey presto problem solved !

Also aware of some 7 series doing the same.

I was told its something to do with the speed sensors being thrown out by a mismatch in wheel rotation speeds .... !

Might be worth checking first.

[aggi]

Egbert Nobacon said:

aggi said:

The SMG on my 328 (E46) is ocassionally staying in a lower gear, it wont change up when taking foot of the go button. Its like when in D the box is behaing like its in S. If you put it in manual, change up then back to drive it sorts itsself out.

Anyone seen this behaviour before? Is it a sign of impending doom!

If its a steptronic ( as a later poster has implied ) are your tyres worn ?

Sounds daft I know but my E39 had similar and was advised to replace worn tyres - hey presto problem solved !

Also aware of some 7 series doing the same.

I was told its something to do with the speed sensors being thrown out by a mismatch in wheel rotation speeds .... !

Might be worth checking first.

Bingo! New Tyre on the front off side, older tyre on the near side, only been doing it since the change, anyone know where (or which wheels) the sensors are on?

[aggi]

StuB said:

I thought the box was sposed to 'learn' your driving style and adapt it's shift strategy accordingly. You might be being a bit heavy footed. Have you knocked the lever forward to attempt a manual upshift?

Its only in drive (so cant manual shift, if I stick it in manual, upshift then put back into drive its fine)

Edited by aggi on Wednesday 22 November 21:20

[Egbert Nobacon]

aggi said:

Egbert Nobacon said:

aggi said:

The SMG on my 328 (E46) is ocassionally staying in a lower gear, it wont change up when taking foot of the go button. Its like when in D the box is behaing like its in S. If you put it in manual, change up then back to drive it sorts itsself out.

Anyone seen this behaviour before? Is it a sign of impending doom!

If its a steptronic ( as a later poster has implied ) are your tyres worn ?

Sounds daft I know but my E39 had similar and was advised to replace worn tyres - hey presto problem solved !

Also aware of some 7 series doing the same.

I was told its something to do with the speed sensors being thrown out by a mismatch in wheel rotation speeds .... !

Might be worth checking first.

Bingo! New Tyre on the front off side, older tyre on the near side, only been doing it since the change, anyone know where (or which wheels) the sensors are on?

I believe its the abs sensors that are used and they are on all four wheels - mine (as earlier posted) was the front tyres, but very worn rears can have the same effect.

[fixedwheelnut]

That is common with different make/size tyres, basically the EGS control unit sees the different wheel speeds and assumes the vehicle is cornering so hangs on to the gear.