[shafah]

Hello! I'm so happy I found this awesome forum and all the resources within it. I did a bit of searching and it seems this problem occurs for some people, but I haven't been able to pinpoint how to solve it. So please forgive my question if there is a thread with a solution somewhere.

2012 e92 xDrive M-sport 6MT

-On the cobb stg 1 aggressive map the car was ok, but didn't feel much difference beyond the boost spike at 3-4k rpm. No unusual sounds or drivetrain issues.

-On the protune map the car is a totally different animal (going to get some dyno pulls and put up my review - PTF has been fantastic!). The initial boost and torque comes on super strong and the car pulls through all the way to 6k rpm. However if I go WOT at 2.5k RPM in 5th or 6th gear there is a rumbling sound and feeling in the middle of the car feels just under the center console or so. It's brief it lasts a second or two and is totally gone by 3-3.5k rpm. It only happens in the long gears where there is a ton of load. I think it's drivetrain related, but I just don't know what. At first i thought it was a heatshield or something that resonated at a certain frequencies. The logs during this time (2.5k - 3.5k WOT pull in 6th gear) look great. I am attaching a log in case someone wants to see it.

Thank you in advance, appreciate the advice and help.

[Dhillon92]

Lack of clamping force on the clutch?

[Cory S]

It's just the engine lugging.... Putting that much of a load in 5/6th gear at such a low RPM/speed causes engine lugging, which can cause strange harmonics through the drivetrain.

[shafah]

Thank you for your replies, i greatly appreciate it.

Originally Posted by Dhillon92

Lack of clamping force on the clutch?

Interesting idea. Does clutch clamping force decline over the life of the component? Meaning wouldn't the clutch just slip rather than transmit a mild rumble vibration for the span of the RPM range from 2.5-3.5k? This car is bone stock except for the tune, if the stock clutch is inherently insufficient for this tune, wouldn't we expect all similar vehicles to have this issue? My understanding is that a minority of people have this rumbling/vibration issue.

Originally Posted by Cory S

It's just the engine lugging.... Putting that much of a load in 5/6th gear at such a low RPM/speed causes engine lugging, which can cause strange harmonics through the drivetrain.

Thank you for your thoughts as well Cory. I am not sure what engine lugging means. All the logs demonstrate normal and expected timing and boost for the tune. There is no timing retardation or misfires. I agree with you that this is some drivetrain issue, but why is it specific to this car and how to solve the problem (other than not putting load on the car in this RPM range).

Thanks again to both of you for your thoughts!

[Dhillon92]

The same thing happens with my car, also MT. I've concluded that most likely, its the clutch, it wants to slip but doesn't entirely. Although if i launch and shift aggressively, the clutch does in fact slip from 2nd into 3rd, etc.

I plan on upgrading it this season so I guess I won't know for sure until that's done.

I can do it on stock tune and it doesn't rumble, only when the most torque is applied at such a low load, this can also be defined as lugging, but mine is kind of drastic. With my clutch slipping that's where my guess is.

[Joey911]

Originally Posted by shafah

Hello! I'm so happy I found this awesome forum and all the resources within it. I did a bit of searching and it seems this problem occurs for some people, but I haven't been able to pinpoint how to solve it. So please forgive my question if there is a thread with a solution somewhere.

2012 e92 xDrive M-sport 6MT

-On the cobb stg 1 aggressive map the car was ok, but didn't feel much difference beyond the boost spike at 3-4k rpm. No unusual sounds or drivetrain issues.

-On the protune map the car is a totally different animal (going to get some dyno pulls and put up my review - PTF has been fantastic!). The initial boost and torque comes on super strong and the car pulls through all the way to 6k rpm. However if I go WOT at 2.5k RPM in 5th or 6th gear there is a rumbling sound and feeling in the middle of the car feels just under the center console or so. It's brief it lasts a second or two and is totally gone by 3-3.5k rpm. It only happens in the long gears where there is a ton of load. I think it's drivetrain related, but I just don't know what. At first i thought it was a heatshield or something that resonated at a certain frequencies. The logs during this time (2.5k - 3.5k WOT pull in 6th gear) look great. I am attaching a log in case someone wants to see it.

Thank you in advance, appreciate the advice and help.

It's the clutch, too much torque at high gear. You can probably lower the torque limit in 5th and 6th so it doesn't try to slip. If I keep flooring it the clutch wouldn't hold and would slip all the way to redline, which is bad.

I don't think it's healthy to have that much torque at high gear... But idk.

Putting in clutch soon, I'll see if it allows high torque in high gear.

[E90 335xi]

It's the car telling you to downshift.. lol