Transmission/Torque converter problem

[Iaro]

The mechanic thinks it's torque converter slipping. When I drive normally everything is fine but as soon a push the car a little to over pass someone or to get on the high way it starts to jerk. It's feel like it looses power for a split second and then it comes back rapidly.

Can the torque converter be replaced? I've decided to start with transmission service and see if new oil will help. Thanks guy!

[Maverik259]

Originally Posted by Iaro

The mechanic thinks it's torque converter slipping. When I drive normally everything is fine but as soon a push the car a little to over pass someone or to get on the high way it starts to jerk. It's feel like it looses power for a split second and then it comes back rapidly.

Can the torque converter be replaced? I've decided to start with transmission service and see if new oil will help. Thanks guy!

Yes but you probably can just replace fluid first and see if that fixed. Then I would look at a rebuild. Very doable by a tranny shop.

Dealer doesn't change fluid or service. They will only replace for $6k

Made my extended warranty worth every penny back in January.

Also on a side note. You can pull the fuse for it in the passenger side fuse box. If the jerking stops then there ya go.

[Iaro]

Originally Posted by Maverik259

Yes but you probably can just replace fluid first and see if that fixed. Then I would look at a rebuild. Very doable by a tranny shop.

Dealer doesn't change fluid or service. They will only replace for $6k

Made my extended warranty worth every penny back in January.

Also on a side note. You can pull the fuse for it in the passenger side fuse box. If the jerking stops then there ya go.

Originally Posted by Maverik259

Yes but you probably can just replace fluid first and see if that fixed. Then I would look at a rebuild. Very doable by a tranny shop.

Dealer doesn't change fluid or service. They will only replace for $6k

Made my extended warranty worth every penny back in January.

Also on a side note. You can pull the fuse for it in the passenger side fuse box. If the jerking stops then there ya go.

Isn't torque converter strictly mechanical? I thought there is no electronics.

[Qsilver7]

Originally Posted by Maverik259

Also on a side note. You can pull the fuse for it in the passenger side fuse box. If the jerking stops then there ya go.

Originally Posted by Iaro

Isn't torque converter strictly mechanical? I thought there is no electronics.

Just an assumption on my part…but perhaps Maverik259 was thinking of the front transfer box? It is electronic and has two fuses in the front fuse box (F32 & F63). I’m not sure which one should be “pulled. If someone knows more…please chime in…my comments are just from being a fence sitter on this topic…I’m just making a casual observation and offside remarks.



1 - Transfer box
2 - Control unit for transfer box (VTG control unit)
3 - Transfer-case servomotor
4 - Servomotor housing
5 - Stator
6 - Rotor
7 - eight‐pin plug connection
8 - Printed circuit board
9 - Cover on the VTG control unit
10 - Plastic housing

Transfer box (VTG)

The control unit for the transfer box (VTG control unit) is secured to the transfer box on the transfer-case servomotor. The VTG control unit controls the transfer-case servomotor. Distribution of the drive torque is oriented upon the torque that can be supported by each axle.

The electronically controlled multidisc clutch smoothly distributes the drive torque as required to the front axle. The rear axle is always powered. This means that all of the drive torque is applied to the rear axle when the multidisc clutch is separated.

The drive torque is distributed as follows in normal driving with four-wheel drive:

• 40 % to the front axle
• 60 % to the rear axle

VTG control unit and transfer-case servomotor cannot be replaced separately: only ever together.

Functional description

In consultation with the central driving dynamics control function in the Integrated Chassis Management (ICM) integrated in the master control unit, the Dynamic Stability Control (DSC) stipulates the setpoint value for all-wheel control of the xDrive function. The setpoint value depends on the tendency of the vehicle to oversteer or understeer and the wheel slip. The setpoint value is transmitted to the VTG control unit.

The VTG control unit regulates the locking torque at the multidisc clutch in the transfer box in responseto the following factors:

• Demand for required locking torque (comes from the DSC control unit)
• Condition of the transmission oil (calculated in the VTG control unit)
• Multidisc clutch wear (calculated in the VTG control unit)
• Load on transfer-case servomotor (calculated in the VTG control unit)
• Transmission oil temperature (calculated in the VTG control unit)

The VTG control unit supplies the following information to the DSC control unit:

• The locking torque currently set
• All calculated data

The locking torque is limited whenever needed in order to reduce the frictional work. This protects the clutch from thermal overload. Locking torque limitation is signalled by a Check Control message.

The multidisc clutch is opened or closed by the transfer-case servomotor. The position of the servomotor shaft and the adjustment rate are detected by a hall effect sensor.

A temperature sensor in the VTG control unit monitors the power output stage for the transfer-case servomotor. This protects the servomotor from thermal overload. Any thermal overload of the servomotor is signalled by a Check Control message. The transfer box moves temporarily into its open position. The multidisc clutch is disconnected. Once the servomotor has cooled down, the multidisc clutch can be operated again (preconditions: DSC must request once-only 0 Nm locking torque).

Due to mechanical tolerances in the production of mechanical components, the characteristics curve of locking torque in the multidisc clutch can vary slightly. The classification function ensures that mechanical tolerances in the transfer box are considered. Optimum function is thus ensured.

When terminal 15 is OFF, a reference run is performed. During this reference run, a certain angle setting of the transfer-case servomotor has a corresponding locking torque assigned for the multidisc clutch. The effects of wear are also taken into account when this is done. The multidisc clutch is closed fully and separated once during this reference run. When this happens, the power consumption is measured at the respective angle setting of the transfer-case servomotor. This determines the beginning and end of the closing action for the multidisc clutch. The angle setting is recorded by means of the hall effect sensor integrated in the transfer-case servomotor. These values are stored and are used as data when the vehicle restarts.

The VTG control unit has an integral controller for emergency operation. The controller is used to attempt to maintain four-wheel drive for as long as possible when the DSC control unit malfunctions or important sensor signals drop out. Substitute values are calculated when individual sensor signals drop out. Functions are operated by using the substitute values until it is no longer possible to control the four-wheel drive effectively. This can lead to the complete loss of four-wheel drive.

[bmwx5er]

Something new I learned today - it appears that you can disable AWD through ISTA temporarily for Gxx models. Not sure if this applies to Fxx too. I'll be sure to check it out this weekend.

Step 3 in https://static.nhtsa.gov/odi/tsbs/20...76367-9999.pdf

[Iaro]

Wouldn't the transfer case throw codes then if there was an issue?

[whoismorggan]

Originally Posted by bmwx5er

Something new I learned today - it appears that you can disable AWD through ISTA temporarily for Gxx models. Not sure if this applies to Fxx too. I'll be sure to check it out this weekend.

Step 3 in https://static.nhtsa.gov/odi/tsbs/20...76367-9999.pdf

Can do this with the xDelete app too

[gasoline]

Originally Posted by Iaro

The mechanic thinks it's torque converter slipping. When I drive normally everything is fine but as soon a push the car a little to over pass someone or to get on the high way it starts to jerk. It's feel like it looses power for a split second and then it comes back rapidly.

Can the torque converter be replaced? I've decided to start with transmission service and see if new oil will help. Thanks guy!

Hello,
This is an old post but I have a very similar problem and could not find the reason
Did you find the cause of this problem? Any help will be appreciated.
Thx

[F15_SGM]

Originally Posted by gasoline

Hello,
This is an old post but I have a very similar problem and could not find the reason
Did you find the cause of this problem? Any help will be appreciated.
Thx

Transfer case calibration or spark plugs. Or the whole trans transmission Could be cause.

[Clifton]

Originally Posted by gasoline

Hello,
This is an old post but I have a very similar problem and could not find the reason
Did you find the cause of this problem? Any help will be appreciated.
Thx

My X5 has never seemed to like expansion joints on overpasses.

Most likely transfer case and very possibly it's time for fluid change followed by recalibration of the VTG.

This might help for a while, but I think some of the stumble shudder is considered normal life with the X5 aka "working as designed".

[stocktree]

Originally Posted by gasoline

Hello,
This is an old post but I have a very similar problem and could not find the reason
Did you find the cause of this problem? Any help will be appreciated.
Thx

I'd bet money, you're misfiring. Change your sparkplugs, and maybe coils.

[gasoline]

Thanks for your comments.
Spark plugs were just replaced but not solved.
When I mention the transfer case fluid, all the dealers say it is a lifetime fluid and does not need to be changed, but I will anyway have it done I guess.
Some say it is the turbine issue inside the torque converter, I hope it is not.
And finally the vanos solenoid seems suspicious, if fluid change does not solve the problem.

[Chilled]

Originally Posted by gasoline

Thanks for your comments.
Spark plugs were just replaced but not solved.
When I mention the transfer case fluid, all the dealers say it is a lifetime fluid and does not need to be changed, but I will anyway have it done I guess.
Some say it is the turbine issue inside the torque converter, I hope it is not.
And finally the vanos solenoid seems suspicious, if fluid change does not solve the problem.

You can pull the transfer fuse or just unplug the electric motor at the TC. If it resolves your issue, the issue is with the Transfer Case.

There are numerous cases of people on the forum having the same experience. Oil change + VTG adaptation and boom, problem gone.


Remember, it is in BMW's interest to say the certain item are lifetime because that means they don't need to service it. There is a grater profit margin in replacing the broken bit.

[gasoline]

Originally Posted by Chilled

You can pull the transfer fuse or just unplug the electric motor at the TC. If it resolves your issue, the issue is with the Transfer Case.

There are numerous cases of people on the forum having the same experience. Oil change + VTG adaptation and boom, problem gone.


Remember, it is in BMW's interest to say the certain item are lifetime because that means they don't need to service it. There is a grater profit margin in replacing the broken bit.

Thx Chilled, I will have it done asap, share the result.

[stocktree]

Originally Posted by gasoline

Thanks for your comments.
Spark plugs were just replaced but not solved.
When I mention the transfer case fluid, all the dealers say it is a lifetime fluid and does not need to be changed, but I will anyway have it done I guess.
Some say it is the turbine issue inside the torque converter, I hope it is not.
And finally the vanos solenoid seems suspicious, if fluid change does not solve the problem.

There's a large thread on here about the same issue. I replaced my plugs and swore I had a trans issue afterwards. Turns out it was misfiring. Changed the plugs again and problem solved. Also check coils, or maybe even replace.

[gasoline]

Originally Posted by stocktree

There's a large thread on here about the same issue. I replaced my plugs and swore I had a trans issue afterwards. Turns out it was misfiring. Changed the plugs again and problem solved. Also check coils, or maybe even replace.

Thx stocktree, I will be checking these also.