Acceleration Studder

[zumbahlenm]

Hello,
I have 2011 X5 50i 4.4l. Last year I replaced all coil packs and plugs. The vehicle has 91k Miles.

I notice that when im driving at cruising speed and I push the gas lightly for acceleration that the vehicle has a light studder. Its almost like a series of small misfires but very light and hardly noticeable.

Does anyone know why this would happen? Is it in the evap system?

[Thecastle]

Unfortunately this can be for a lot of reasons; I've fought these problems before and you'll need to start troubleshooting and get more information. Start with pulling the engine codes with a BMW scanner to see if the engine is healthy. If that doesn't reveal anything.. Your best bet is to take it to a mechanic, who is experienced with this, and have them do a visual check of the suspension, wheels, guibo. More often then not its a drivetrain/suspension problem.

Generally this issue is caused by;
Bad/out of round tires - most common
Bent rims - most common
Engine misfires/Vanos
Carbon Build up
Vacuum leak
Bad Guibo - pretty common
Bad torque converter
bad XFER
bad diff
bad/out of balance drive shaft
suspension problems
bad fuel
bad engine mounts
bad rear diff mounts
bad trans mounts
worn suspension
bad transmission
and etc.

A lot of these a competent mechanic who gets it up on the lift and knows these cars will be able to identify the issue.

Personally if a visual inspection by a BMW mechanic/code pull doesn't reveal anything significant, I wouldn't worry about it. These problems can be very hard (aka expensive) to chase down. Lots of threads on this.

[Sophisticated Redneck]

Originally Posted by zumbahlenm

Hello,
I have 2011 X5 50i 4.4l. Last year I replaced all coil packs and plugs. The vehicle has 91k Miles.

I notice that when im driving at cruising speed and I push the gas lightly for acceleration that the vehicle has a light studder. Its almost like a series of small misfires but very light and hardly noticeable.

Does anyone know why this would happen? Is it in the evap system?

I second what Castle said, get yourself a good scanner that can read BMW codes like the foxwell nt530. Make sure if has the BMW software on it. To many variables on what it could be and you will be chasing your tail without one.

One more thing to add to check to what Castle already wrote. When you get the scanner, look for any transfer case codes. A set torque code can cause a strange sensation when driving that can misinterpreted as a engine miss (feels like a miss but the engine rpm or tone never changes). This drove me nuts for weeks until I figured it out. Usually easy fix with just fluid change and recalibration of the transfer case.

Also if it is a engine miss, you can access the generic ob2 misfire counters with the scanner. This records every misfire for each cylinder for each drive cycle (it auto-clears every time you start engine). Very handy for tracking down misfires that are not severe enough to trigger limp mode codes.

[Bengineer330]

I had a similar issue, felt like I was pulling a trailer, or something was “tugging” the car from the back whenever I accelerated gently. Wide open throttle it wasn’t as noticeable.

Replacing the Transfer Case Fluid did the trick for me. Only use the OEM, it’s expensive but worth it. Re-Adapt the limits if you have the software too.

[shark715]

We also own an '11 50i (81k miles) and seem to be experiencing the same exact issue as OP. Until I read this thread, I was fairly confident the issue was the driveshaft.

Our original front driveshaft broke 6 years/30k miles ago and was replaced by BMW for free even though the car was already out of warranty and the 10 year/120k mile driveshaft warranty extension had not yet been announced. At that time there were already numerous reports of driveshaft issues and no doubt BMW already was fully aware they had a problem.

The current shuddering feels exactly like what we experienced before the original driveshaft broke. Is it possible the replacement driveshafts are no better than the original ones? Unfortunately our car is now 11 years old and beyond the extended driveshaft warranty. If the car needs another driveshaft again I'm going to be very unhappy if BMW does not replace it for free.