ukr

I've noticed that my '06 530i and '04 525i have exact same problem with delayed trans engagement when pulling away from a stop. I would step on the gas pedal, engine rpm would go up a little, and then the car starts moving...very abruptly. It's almost like dropping a clutch. This makes the vehicle lurch from a stop. Seems like something in the trans isn't engaged immediately...anybody else noticed this issue or know what the fix is?

jtbgonesailing

Have you checked for BMW specific codes? Has the fluid been changed?
ZF the manufacturer of our automatics has established a fluid/filter pan change interval of 40-60k miles.

Any other issues with transmission?

ukr

No codes. 06 530i did this since it was practically brand new. Sometimes it doesn't..but most of the time it does. I'm a bit suspect that both cars from two different years and engine configurations due the same thing...I've never experienced anything like this before from an automatic. It's very noticeable when the car is on a steep incline...depress the gas pedal, rpm rises to a little over 1k and then it's like somebody drops the clutch...

One other issue I've noticed is that occasionally a shift from 2nd to 3rd or 3rd to 4th (not sure which one) at over 3k rpm, one of those gears doesn't grab immediately...the rpm would suddenly overshoot a little before it engages the gear.

Don't know the inner workings of ZF automatic, but could there be a pressure leak that's causing something not to engage immediately?

frenchyrider267

I'll put my two cents in here; Disclaimer: this is in no way shape or form an "expert" opinion. I'm merely a DIY'er who loves tinkering with his cars. So if anything in the below comments sounds retarded or not factual, I'm not claiming to know exactly what's going on; just my opinions and experiences.


I noticed this with both my 2004 525i as well as my wife's 2008 528i. Here's what I think as I experimented with them a little bit. I believe when you come to a stop the engine is temporarily electronically "disengaged" sort of speak. It's not, but it seems like it. I've noticed with other vehicles I've had (not high end) where I am sitting at a traffic light that there is constant pressure on the driveshaft it seems to me and if I were to lift my foot off the break I immediately start to move forward from the idle.


so I took this experience with other cars and experimented by sitting at a traffic light and lifting my foot off the break in different styles from a complete stop. First abruptly and immediately attempting to gas; There is a hesitation before I feel the drive kick in and start to move the vehicle forward resulting in a slight "jolt" almost like the tranny is slipping.


Then from a complete stop, letting off the break for a full second before applying pressure to the gas peddle, and it never hesitated nor jolted. This was all with the shifter in the "D" position.


So I've read other places about the "DS" mode that the car has more responsive everything. So out of curiosity I tried the above experiment in the "DS" position and it doesn't happen at all, and of course if I manually shift it never happens. I think due to the different modes (D, DS, M/S) the engine reacts different with each, hence not prepared for a fast launch in "D" as it is in "DS" or "M/S."


It's just an experiment. What do you have to lose by trying it out. In short, I think the hesitation doesn't mean anything. I think the car is reacting as it should in my honest opinion.

audiophool

Some automatics unload the engine when you're stopped, idling with the brake on. They do it by switching to 3rd or 4th gear, which reduces the fuel burned during idle. As soon as you lift your foot off the brake, it's supposed to shift into first and off you go. To test, try putting the gearbox in manual mode and select 1st gear. If it doesn't do it then, suspect the above feature.

I first experienced this nastiness on a VW Jetta I rented on Maui. I had to run that car in Sport for the whole trip otherwise I'd snap everybody's neck on every start.

jtbgonesailing

frenchyride267, You've got it! Only item to add is in D, the car is actually starting in 2nd as apposed to DS=1st and yes the torque converter is actually decoupling with your foot on the brake in Drive.

DanielFD

Also to add to this, i had a friend that was telling me he was having tranny problems where if he was in an incline and engaged D or DS or R that it would take a second for the car to start moving or if he pressed the gas pedal he would feel a jolt. That was the autohold function on the brakes that was making him loose his mind. The car keeps pressure on the brakes for a couple seconds if your on an incline and lift of the brakes.

ukr

Sounds like good idea to decouple engine from trans at idle but horrible execution on BMW's part. I didn't expect this behavior from a premium automaker. It's annoying and in some instances dangerous.