Transmission 4-5 slip, but not in sport mode

[PeterPeterZ]

2007 Z4si. When I nail the throttle, I will get a 4-5 slip and the orange wagon wheel fault light on the dash. I set myself up years ago with a Windows 8 laptop with INPA, so I'm able to see the fault which comes down to a Mechatronic rebuild, and I get that. I'll do it when I have the time.

But when I have sport mode selected on, I can drive like moonshine runner and never get the first slip. I've read plenty of posts stating that sport mode just changes the timing of the shifts and all that, but if it never slips in sport mode, I think there is something else going on rather than just shift timing. The rubber seals are probably hard as rock, but sport mode rocks. Does anyone know, like really know, why this is?

My apologies to our euro friends who may no know what a moonshine runner is. It's running from the police with a boot full of illegal corn whiskey.

 

[smorris_12]

World it be right to say that you get the slip error at low revs and wide throttle openings? Whereas in sports mode you've got the revs up?

Wondering if it's a box oil pressure thing.

 

[PeterPeterZ]

I'm throttled for high power and torque, it slips going from 4-5, rpms jump and the fault appears. The question of interest is not what is causing the fault, but why does it not happen is sport mode? Yes I agree, the sport mode likely has higher revs.

 

[axelleveau]

I'm throttled for high power and torque, it slips going from 4-5, rpms jump and the fault appears. The question of interest is not what is causing the fault, but why does it not happen is sport mode? Yes I agree, the sport mode likely has higher revs.

If it slips going FROM 4 to 5 instead of while ENGAGED in either gear then I'd say Sport mode probably helps by applying more pressure to the clutches (during the shift, I expect it is the same once in gear) and shift quicker not allowing the slip to get starting. This is a bit worrying overall still, either the oil pressure is always a bit low or some clutch pack is worn. Might be worth doing an oil change. Not familiar with the auto box, is there some sort of filter too?

 

[PeterPeterZ]

Yeah, it has a filter. It looks just like those chunk filters on the front of a window air conditioner. It just washes out in the sink. I can't believe people actually buy those things in a kit, and with an oil pan they don't need. I'm rambling. Thanks for the thoughts. Valves and seals will prob fix it.