E39 535 V8 auto box wierdness

[fwaggie]

Car is a 1998 R reg.

Now I know that these boxes hold onto a lower gear for a little while if you give the loud pedal a firm prod.

Maybe 10 to 30 seconds before it decides you haven't actually turned into Colin McRae and it then decides to go back into waft mode.

My car is doing this, but rather than sit in a lower gear for 10~30 seconds it just seems to sit in the lower gear permanently. I've left it revving it's head off (relatively) for a few minutes (maybe 3~4) and no sign of changing up.

If I turn the cruise control on it DOES go back into waft mode within a second or so (ie changes up).

Put it into S mode and back in to D, problem remains.

If I speed up so it has to change up due to revs being maxed out, it will then go back into waft mode.

If I slow down to 20 mph or so, it change down, but will still refuse to change up when I speed up (unless I kick down).

If I slow down to almost stopped, it goes back into waft mode.

If I use kick down it goes back into waft mode (I think).


The fact the box happily changes up when the cruise control is turned on leads me to believe there isn't anything mechanically wrong with the box, and I'm wondering if the 'box ECU needs the latest program loaded onto it? Was this a known problem at one point?

[Pickled Piper]

My E39 was doing something similar but also showed the ABS and traction control warning light. A change of front ABS sensor fixed the problem.

I have also read that a difference in wear of the rear tyres can cause similar issues.

pp

[fwaggie]

Pickled Piper said:

My E39 was doing something similar but also showed the ABS and traction control warning light. A change of front ABS sensor fixed the problem.

I have also read that a difference in wear of the rear tyres can cause similar issues.

pp

The TC light isn't on unless I'm playing silly buggers.

And the ABS light isn't on either.

Something to bear in mind though, I guess if an ABS sensor is bad, it will be logged in the computers fault list.

Thanks.

[Oi_Oi_Savaloy]

It could be the solenoid pack has packed up?

[dan101smith]

First step would be to get the auto box adaptive values reset - if you're near Herts I can do that for you.

[hoppo4.2]

the box on my alpina did this and was also hesitant between 1st and 2nd some times it can be caused by faulty abs sensors and even very uneven tyre wear. however i found that my gearbox oil cooler had a slight leek. resulting in low oil levels. replaced the cooler and refilled and the box is silky smooth better than it has ever been.

[Steven Quas]

On newer BMWs (and quite possibly older ones) you can reset the learned behaviour of the gearbox by putting the ignition to position 2 (all the lights come on) but don't start the engine. Press the accelerator to the floor and hold it for 30 seconds, then release it. Switch the ignition off and then start the car as normal. It should have forgotten it's odd behaviour. Can't be guaranteed to work, but worth a try, given that it's free....

Steven Quas
Hamburg

[dan101smith]

I suspect that procedure will only work on the fly-by-wire throttle cars, which a '98 E39 won't be.

[fwaggie]

dan101smith said:

First step would be to get the auto box adaptive values reset - if you're near Herts I can do that for you.

Milton Keynes, so yes.

Where abouts are you? My email is [e-mail] if you want to keep it off the forums.

One thing I have noticed today is that the nearside rear tyre is rather flat which I would guess will upset any abs/traction control system (can't see why it'd upset the gearbox though unless it's a lot more intelligent than I thought and refuses to change gear when the car is going round a bend).
(How come tyres can maintain a slightly lower pressure for ages, and then when you check them and blow them up they seem to "remember" they've got a slow puncture? Grrr!)

I'll obviously sort that out now I've noticed it and see if that changes anything.

I know when I got the car (3 months ago) it did the usual behaviour of sitting in the low gear for 10~30 seconds and then changed up.

[Steven Quas]

dan101smith said:

I suspect that procedure will only work on the fly-by-wire throttle cars, which a '98 E39 won't be.

I can't remember when they switched over from cable, but I would have thought it might work as the E39 had a steptronic auto (from memory). Certainly worth spending 30 seconds trying it out. Otherwise just disconnect the battery for 30 minutes so the gearbox forgets what it has learnt.

Steven Quas
Hamburg

Edited by Steven Quas on Thursday 17th March 23:07

[fwaggie]

My car definitely has a cable, but you make a good point as the kickdown switch will be engaged with the throttle flat to the floor.

Can't hurt but to try.

[fwaggie]

I feel a bit of a wally now

Inflated the mostly flat nearside rear.

Gearbox now behaving itself perfectly.

(and it's driving better in general too)

[Steven Quas]

Glad to hear you solved it and without any expense.....

Steven Quas
Hamburg

[Crombers]

Mismatched tread depth can also cause this.

Took me months to get to the bottom of it on my old 540, had to change gear using the shifter.

A new set of boots later and all was well! Inflating one of the tyres is a cheaper option though