Z4 3.0Si auto gearbox - few questions

[esafaeian]

Hey Guys,

Weather has been really hot here recently and a few issues have started popping up with my z4 coupe

I have another thread for issues with the starter/battery but just want to post a few more questions here about the auto box in the z4.

My car has 130k km on it, as far as I know the auto gearbox oil is original/never changed (full service history but don't know if previous owners changed the fluid before 125k km). I've noticed two issues recently, sometimes when I engage sports more it'll change back to D and then back to sports by itself without me touching anything... The other thing I've noticed is that if I put it into manual mode and then hit the sports button sometimes when I'm holding it on 3rd or 4th gear it will automatically shift up to the next gear - I was under the impression that I could hold the rpms in whatever gear I was in when in manual and sports mode. Also when I slow down in sports manual the gearbox automatically shifts down but only into second, it doesn't auto shift back to 1st, and I have to manually put it into 1st if I want to take off in 1st gear, is this normal?

Finally when driving around normally in D i feel sometimes that the gears aren't shifting down when I'm slowing down, like I'll slow down or start going up a hill and I feel like its still holding the gear without shifting down and then I have to press a little harder on the accelerator to get it to shift down but there is a lag and i hear a slight metallic sound under the car, possibly pinking?

I would greeaaaaatly appreciate any help I can get! Thanks guys.

[mr.tourette]

some bits sound odd.. the dropping to 2nd at standstill is normal tho, the only time you'll get 1st is when first starting the car, the car will change gear in manual if it senses you are straining the engine/box in any way as a safety measure. The accelerator does adapt to your driving style over time, worth trying the accelerator reset procedure to see if it helps out with the down changing on hills etc although I sense something else may be at play here its worth a try.. make sure your battery is in good health too as poor condition batteries can manifest all sorts of electrical issues on these cars

[esafaeian]

Hmm not too sure about the battery, it has a green indicator on it which I would assume means it’s ok? Although I haven’t touched it in the 7-8 months I’ve had the car and not sure when it was previously changed..

[mr.tourette]

Still worth taking it off the car and making sure its fully charged and checking voltage with a multimeter

[esafaeian]

I checked it on the dash using the secret menu and it showed readings between 13.5-14.3 (mostly around the 14 mark and only dropping when activating things like air con). Is this an accurate/reliable way to check battery health? I’ll continue to monitor (didn’t have any issues with the gearbox driving to work, although I did reset accelerator and gearbox procedures), hopefully it’s bothing too major..