[jxterma]

Got my x35i for 2 months. After driving it for 3 weeks, I notice the car was not (or at least feels like)moving with expected torque when pulling from traffic light. The hesitation does not seem to come from the engine, in fact, RPM cranks to 3K right away with fairly firm press on the gas, but feels like the transmission is not selecting right gear or wait for a few seconds to pick up right gear.

There is no warning light or error. I took it to the shop last week and computer read 2 error codes, one for transmission running under safe mode and SOS failure. For transmission error, service guys reset adaptive transmission and flipped on all parameters(not sure what that means). The car is running better now. It starts moving quickly at 2k RPM and gear change is smoother. I asked if the problem could come back and why it occurred in the first place(shouldn't PDI cover those check prior delivery?). Didn't get a straight answer, so will wait and see. Could driving behavior causing this?

[jxterma]

Forgot to mention SOS error. It was program failure. Service guys tried to install upgrade but failed. They said it's not a unique problem to this car or this model. A number of 3 series and X5 have same problem. Now BMW is working on version 4.4 which should be released next month.

[xDrive35i]

That's typical of most 35i (N54/N55) cars. There's no concrete fix. They say it's transmission software--an update for which is long overdue at that.

[Dukat]

If you're referring to the 'throttle lag' where you press the pedal a little, nothing happens, then past a certain point it takes off yes, that is normal. Best guess is it's a gas saving feature.

It's very annoying and it does appear to be part of the programming because in Sports+ mode it's much less noticeable.

I let a friend try my car a few days ago. He said, "It's awesome, but what's with the lag".

[mibmwx3]

Originally Posted by Dukat

If you're referring to the 'throttle lag' where you press the pedal a little, nothing happens, then past a certain point it takes off yes, that is normal. Best guess is it's a gas saving feature.

It's very annoying and it does appear to be part of the programming because in Sports+ mode it's much less noticeable.

I let a friend try my car a few days ago. He said, "It's awesome, but what's with the lag".

What version software are you on? I'm using MX-003.004.031 and don't feel the lag.

[Dukat]

Originally Posted by mibmwx3

What version software are you on? I'm using MX-003.004.031 and don't feel the lag.

I have the same software version, but that is the 'multimedia' software. I think the transmission/engine control software is something else, don't know how to check it.

To more accurately describe the issue, it's the amount of distance you have to depress the pedal before the engine responds. Most cars go as soon as any pressure is applied. In the new X3's you have to depress the pedal a set distance before anything happens. The term 'lag' is misleading. I think it's use started because it appears to be a lag from when you start pressing the pedal.

[mibmwx3]

Originally Posted by Dukat

I have the same software version, but that is the 'multimedia' software. I think the transmission/engine control software is something else, don't know how to check it.

To more accurately describe the issue, it's the amount of distance you have to depress the pedal before the engine responds. Most cars go as soon as any pressure is applied. In the new X3's you have to depress the pedal a set distance before anything happens. The term 'lag' is misleading. I think it's use started because it appears to be a lag from when you start pressing the pedal.

Oh, I see. I used to experience this lag too, but it mysteriously stopped. I don't know how or why.

[sard]

Originally Posted by Dukat

I have the same software version, but that is the 'multimedia' software. I think the transmission/engine control software is something else, don't know how to check it.

To more accurately describe the issue, it's the amount of distance you have to depress the pedal before the engine responds. Most cars go as soon as any pressure is applied. In the new X3's you have to depress the pedal a set distance before anything happens. The term 'lag' is misleading. I think it's use started because it appears to be a lag from when you start pressing the pedal.

Exactly.

[Beyu]

Originally Posted by mibmwx3

Oh, I see. I used to experience this lag too, but it mysteriously stopped. I don't know how or why.

I think after your car loosens up a bit after breaking-in it helps to alleviate the problem. Another thing that might be helping is perhaps you're just more comfortable with your X3 now and are a better judge of how hard to depress the pedal before it accelerates.

However, I still can't explain why the car "lurches" sometimes during initial acceleration or de-acceleration.

[tuco44]

Originally Posted by Dukat

I have the same software version, but that is the 'multimedia' software. I think the transmission/engine control software is something else, don't know how to check it.

To more accurately describe the issue, it's the amount of distance you have to depress the pedal before the engine responds. Most cars go as soon as any pressure is applied. In the new X3's you have to depress the pedal a set distance before anything happens. The term 'lag' is misleading. I think it's use started because it appears to be a lag from when you start pressing the pedal.

Agree the term "lag" is misleading. Not really a lag at all. I had an N54 engined 2008 535xi couple yrs back, and the turbo engine in that car accelerated exactly as the N55 engine does, if anything less noticible with the N55 X3. I am used to it after several months use, and have no problem with it. Just don't mash the go pedal to the floor off dead stopped, and you will have no problems. Get used to it, turboes are the new wave.

[TreeSkier]

When I first picked up my car with 35 mi on it, I experienced this dramatically and had to be very gentle with the gas when taking off from a stop. I had my car in and they reset what they called the "Engine Adaptation" and the car has been better since then. I'm now at 1200 mi. The accelerator is still touchy though and I have adapted to it somewhat, but it's much better than when I picked up the car.

[jxterma]

Originally Posted by Dukat

I have the same software version, but that is the 'multimedia' software. I think the transmission/engine control software is something else, don't know how to check it.

To more accurately describe the issue, it's the amount of distance you have to depress the pedal before the engine responds. Most cars go as soon as any pressure is applied. In the new X3's you have to depress the pedal a set distance before anything happens. The term 'lag' is misleading. I think it's use started because it appears to be a lag from when you start pressing the pedal.

Probably everyone is tired of this topic as I have seen pages of discussion around hesitation problem, but here is some update.
First I forgot to mention mine is F25(could be worse with more electronic control added). I took a closer look on what happens. When I pressed the pedal, yes, I noticed the distance before engine picked up, but on top of that when engine reaches 2000rpm, the car is still not moving, not before almost 1-second delay.
This time dealer successfully upgraded the software which fixed the SOS problem and cleared the transit mode.

Invoice shows: ISTA/P 2.46.5(Canada version)
Charge: FREE
Three new modes appears on iDrive:
- Sport Chassis and Drivetrain
- Sport Chassis only
- Sport Drivetrain
I have no idea what those mean.

As for acceleration I do not notice any significant change, but other owner with similar upgrade does feel great improvement.
http://x3.xbimmers.com/forums/showth...ght=hesitation

Lag or not, I'm more used to the car now and taking this as a different driving experience instead of a problem. After all it is a different car. I cannot expect it feels/drives the same as my old A6. I have peace now. Thank you all for sharing your experience/thoughts