Z4 acceleration

I have a 2005 2.5L Z4 automatic. It seems to me there is a slight hesitation when I start from a complete stop. Then it takes off. Not smooth at all.

This is in contrast to my Toyota truck (stick) which does not hesitate at all.

Also, I was messing with the S/R and clock buttons when the odometer changed from miles driven to number 6. I managed to increase the number to 8 before it went back to mileage. Anybody else ever done this?

Reply to
nobody
Loading thread data ...

Is your car truely automatic or is it SMG? What you are describing would be about normal for an SMG transmission.

Reply to
RJD

I was unaware of it until you brought it up but it is a SMG transmission. I can either put it in drive or pull the shifter towards me. I tap it up to increase the gear or tap it down to down shift. I normally drive it, and the reason for the post, in drive and do not change gears manually.

Thanks for the help. Now I am going to research it to see if I can adjust it to help eliminate the hesitation.

Reply to
nobody

I'm in the rare position of having driven all the BMW SMG transmission offerings (thanks BMW Performance Center!) and they all exhibit the hessitation. As you prbably know the SMG is really a manual transmission with an automated clutch. I think the delay is just the combination of the ECU having to see your foot release the brake and apply throttle input so it knows you want to move forward. That decision making process plus the actual movement of the clutch takes a fraction of a second and you can feel it. I'm not aware of any improvments that BMW can offer (but do check it out). You might want to investigate the aftermarket (ie.

formatting link
as some of them might have an improvemnt to the software. Dinan modificatiosn do not void your warranty.

Good luck

Reply to
RJD

I took it to Dinan and it turns out to be a steptronic transmission and not SMG. However they said the same hesitation is found in both. One tech said he noticed it in his 325 and upgraded the software which seemed to help the response. The software is $299 with an hour of upload. Bad news is the software is 49 state legal (not California) but they are trying to get it accepted in California. I will probably purchase when it is accepted or BMW provides an upgrade.

Reply to
nobody

MotorsForum website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.