[juxtap0se]

Hello all,
2011 328xi 6MT Wagon 81k miles - rebuilt title.

Since buying the car a few months ago I've started to notice a vibration/rumbling sound and slight loss of power when shifting into 3rd gear around 1800-2200 rpm. It clears up afer a couple seconds of acceleration and doesn't seem to happen if I shift into 3rd at lower rpms (maybe 1200-1500) and then accelerate from there. I've had no codes come up at all.

Based on research I'm thinking there could be a xfer case problem. Today I pulled the transfer case actuator fuse (F40) and was unable to replicate the issue after about 15 minutes of driving. 4 X 4 warning light came on immediately but the car drove better overall.

I mention the rebuilt title because I'm wondering if it could have been towed incorrectly after the accident, damaging some of the transfer case components. From what I understand the actuator has plastic gears, which are probably made that way in order to fail and not do damage to other parts when something bad is happening.

I've already done some other recent maintenance items to rule those out/for fun.
-Plugs and coils
-Engine filter/Clean MAF
-Clean and swap VANOS actuators
-Clean VANOS check valves
-Fuel injector cleaner
-Oil change and filter

My questions:
- Is driving with the transfer case fuse removed safe for the components for more than just a quick test? I'm assuming this disables dynamically sending power to certain wheels so it may be less safe in terms of traction and stability.
- Is any more diagnosis possible without getting in there to remove and check the gears or putting in a new actuator?

Thanks!

[Brian86]

No harm will come to the car driving it with the transfer case fuse removed.

It's also perfectly safe to drive the car with the front driveshaft removed, although the computer will periodically figure it out and flash malfunctions at you.

Just shooting from the hip, but having had the transfer cases and transmissions out of these cars:

Towing with the front wheels on the ground is bad, because the front wheels will be turning the transfer case, but the transmission output will remain idle. While the wet clutch is 'disengaged' when the car is off there is still sufficient drag when the speed differential is bonkers high to smoke the wet clutch.

Towing with the rear wheels on the ground is also bad. In addition to the same problem above with the transfer case it will also smoke the transmission just like any car because the output shaft will be spinning, but the transfer shaft is idle so the fluid stays stuck in the bottom.

x cars need to be on a flat bed, 4 wheel dolly, or front wheels on the ground with the front driveshaft removed. Of course this really only applies to road speeds. If you're just moving it around the driveway or something it'll be oK.

A bad tow won't hurt the actuator gears... unless the Xfer case got so hot it actually melted the plastic, but if that happened you should just get 4x4 errors all the time.

My gut says it's in the engine, not the transfer case. Nothing the transfer case does should be able to suck power out of the engine or cause vibrations unless other things in the drivetrain have some pretty profound malfunctions.

I'd assume there aren't any relevant DME malfunction codes?

Recommend reinstalling the actuator fuse, removing the front driveshaft, then clearing the codes. The car doesn't really know the front driveshaft is missing unless you spin the tires so it'll drive without any malfunction conditions. See if the problem persists.

[juxtap0se]

Thanks for the info. Drove around for a couple hours yesterday with the fuse still out and still had no issues come up where it was happening pretty much every time shifting into 3rd before. I'll put it back in today to see what happens, and look into removing the front driveshaft.

Seems like it might just be converted to a RWD car for the time being unless I can find another issue.

Any suggestions on any testing I can do against the engine for issues?

[ome91]

One thing I would also check is when the last time your Transfer Case fluid was changed. Ditto for removing the front driveshaft, sometimes there can be a lot of play in the U-Joints, than can cause vibrations and such.

[juxtap0se]

Originally Posted by omer_has_a_bmw

One thing I would also check is when the last time your Transfer Case fluid was changed. Ditto for removing the front driveshaft, sometimes there can be a lot of play in the U-Joints, than can cause vibrations and such.

Yeah, I'm planning to try to get at the transfer case to do a fluid change eventually. Gotta get a better jack/jackstand setup so I can keep the car level and get the tcase bracket out.

[juxtap0se]

Just an update on this one in case anyone else is running into similar issues - double check that your tire sizes match!

I had sworn that I looked at the tire sizes before but lo and behold a few days after making this post I checked again and they were mismatched. Even had it into the dealer for inspection and they didn't mention anything. Swapped to matching tires and the issues disappeared completely!