For anyone with Autogearbox rough changes & loss of cruise control

[bear2020]

Car BMW Z3 3.0 2000

I had issues with the gearbox and down changes from 3rd - 2nd & 2nd - 1st

Initial inspection threw up no codes so I marched forward and changed the following
Gearbox fluid, tranny fluid, gearbox filter and all parts needed to change that.
Result - Nothing
Also at this point noticed the cruise control would no longer work

Again checked codes and nothing related to gearbox or engine came up. Gave up and put it away for the Winter

This year with fresh determination to get it resolved I spoke to a gearbox rebuilder who said it would cost up to £2k for the mechatronics to be re-built. I cried.

I took the car for a drive and the issue was still there but noticed something on the engine data that I had not noticed before and this was the amount of air passing through the MAF was not being read. It was also throwing up a torque convertor issues and crankshaft sensor issue but NO MAF error

I started to read about the DME (Digital Motor Electronics) and unplugged the MAF and took it for a drive. The gearbox issues were a little less but not that much.
Again read the codes and this time the MAF was showing a fault. Probably because it had been unplugged

With the prospect of £2k or a new MAF directly from BMW for £65 I opted for the latter

New MAF fitted and all codes cleared

Completed 92 miles so far every single gear change was smooth and the cruise control now works. No engine codes and the engine and gearbox responds how it should.

The car was obviously reading corrupt data and the gearbox did not know when to change and was not doing so within the parameters so it just "dropped" changing down.

Spoke to my local garage (Couple of the lads are into their BMWs) and had never heard of a MAF throwing a gearbox out. After discussing it with them at length and the fact NO codes were shown and what the DME would be telling the gearbox I took the car to them and put the old MAF back on and then the new one. They were surprised and even with their software no engine codes were thrown up or gearbox. We even checked the engine management lights work (they do) but it was a surprise for them.

So just for reference even though you may not get a code from the MAF if you can view the live DataStream and see what the MAF is running either with the flow or the Voltage. Both will be zero if it is not working,

Happily have a car back that now runs how it should changes gear and cruise control. And to think I stopped using it for a year to try and get to the bottom of the issue and was going to rebuild the gearbox! What a plonker who knew it would be such an easy fix!

 

[Peter1450]

Sounds just the same as my wife’s 3.0 , did all the fluids and filter as you did but seems to have a mind of its own!
Where did you get a genuine MAF for £65 ? TIA

 

[DrWong]

Glad you got it sorted mate and thanks for sharing the solution

 

[AntStark]

I was going to ask you about this, thanks for posting. Mine does similar and is more pronounced in sport mode. I am going to get the oil and filter done anyway but will look at this if no marked improvement. Ditto where BMW MAF for £65 !?

 

[bear2020]

I was going to ask you about this, thanks for posting. Mine does similar and is more pronounced in sport mode. I am going to get the oil and filter done anyway but will look at this if no marked improvement. Ditto where BMW MAF for £65 !?

BMW Parts online
www.bmwpartsonline.co.uk
1493900700 Air Mass Meter £51.95
3946S0002 Camshaft Sensor £17.01
3946S0016 Exhaust Camshaft Sensor £17.68
Total £86.64, Shipping £7.30 Vat £18.79 total £112.73

Whilst you have the air box off to replace the MAF I changed the sensors as well and it is literally a 30min job. You'll need a 32mm spanner for the VANOS solenoid and might have to take the oil feed pipe off (19mm spanner) off to remove the sensor (5mm allen key) but it is a very easy job to do.

Be interested to see if it works for you as well!

 

[bear2020]

Sounds just the same as my wife’s 3.0 , did all the fluids and filter as you did but seems to have a mind of its own!
Where did you get a genuine MAF for £65 ? TIA

www.bmwpartsonline.co.uk

 

[Peter1450]

Thanks for the link, says JP group for the MAF , not heard of them, thought it was too cheap to be Genuine BMW.
The general consensus on the forums is only genuine for sensors etc but it seems to have done the trick for you.

 

[bear2020]

Company name

Company name

www.bmwpartsonline.co.uk

This is the site I used and delivery was within 2 days

 

[bear2020]

Thanks for the link, says JP group for the MAF , not heard of them, thought it was too cheap to be Genuine BMW.
The general consensus on the forums is only genuine for sensors etc but it seems to have done the trick for you.

It came from BMW with a BMW guarantee and a BMW receipt, that for me is good enough and not an Autodoc item

 

[Pond]

It came from BMW with a BMW guarantee and a BMW receipt, that for me is good enough and not an Autodoc item

bmwpartsonline.co.uk only have a mobile telephone number and their trading address is a tiny terraced house in Harrogate. Seems a little odd to me.

 

[AntStark]

bmwpartsonline.co.uk only have a mobile telephone number and their trading address is a tiny terraced house in Harrogate. Seems a little odd to me.

Lots of small online parts resellers operate from their own homes, don’t see any issue with that per se. Be interesting to see how long that MAF last though..definately a 3 missing from the front if you compare the price of a BMW one (which I think were Bosch on the M54).

 

[Andyboy]

Febi MAF's seem to be Bosch or Siemens with the part numbers and logos ground off.

Talking of gearbox issues: I had a 1997 single Vanos E39 528i auto that would not change up into 4th or 5th unless you did it manually on the gearlever - occasionally on ultra light throttle it would go into 4th on its own. Everything was checked - no fault codes. I replaced the Chinese MAF with a known good Bosch one and whilst it certainly went better, the gearbox still wouldn't work properly. A SnapOn diagnostics tool was used to measure wheel speeds from each ABS sensor - all showing good. I even replaced the gearbox valve block with another one and ditto the ECU - no different.
One day though, the ABS dash light pinged on. Faulty front left sensor. But now the gearbox worked perfectly. A new sensor was fitted, no ABS light....but the gearbox problem was back. Removing the ABS fuse restored the 'box to working order but it as noticed that the ABS pump/ECU was very hot to touch. A good used unit fixed it.

Just shows.

 

[bear2020]

bmwpartsonline.co.uk only have a mobile telephone number and their trading address is a tiny terraced house in Harrogate. Seems a little odd to me.

I think we are missing the point. It was not about where the MAF came from but how the problem was fixed. By all means someone can pay £300 for a new MAF but the post was about how it got fixed and if that helps someone that's great. Didn't mean for it to get into a contest about a MAF

 

[Jam03]

This thread reminded me of something. Back in the early 1990’s I remember that BMW bragged about their new adaptive automatic gearbox that would adapt to your driving style. I think some Z3’s also have the adaptive auto that takes inputs from lots of the sensors related to ABS and stability control and others in order to decide what mood you’re in and alter the way the box behaves. I guess it’s not surprising that any of those sensors not working properly could result in a poorly behaved gearbox.

 

[AntStark]

In that case.. I am surprised mine works at all given the mood I am in most days

 

[bear2020]

This thread reminded me of something. Back in the early 1990’s I remember that BMW bragged about their new adaptive automatic gearbox that would adapt to your driving style. I think some Z3’s also have the adaptive auto that takes inputs from lots of the sensors related to ABS and stability control and others in order to decide what mood you’re in and alter the way the box behaves. I guess it’s not surprising that any of those sensors not working properly could result in a poorly behaved gearbox.

Yes you can reset the auto gearbox as I have done it on the Z3 and the F31 335d I have. I was and had started to look at the price of all the gearbox sensors and was going to do a full rebuild. I'm happy it was just the MAF. Just surprised it never threw a code up or engine light!