[SF335]

I just installed an M Factory LSD in my 2011 e92 (n55). It's a 6MT and I changed the final drive ration from the stock 3.08 to 3.46. Everything is great except that I am having problems with cruise control. Cruise won't engage in 5th and 6th gears unless I am going around 84 mph. Even then it is sporadic and sometimes doesn't let me engage. In other gears, cruise engages just fine.

I am wondering if this is due to the change in the final drive ratio. There was also a lot of suspension work done and a diverter valve installed but I cannot imagine that being related.

Does anybody know what may be causing this? Thank you!

[feuer]

Do you have the Kombi coded for accurate speed? My winter to summer set have 4.2% front and 5.7% rear difference. 65mph on winter is 61mph on summer set and don't have problems with cruise control.

[SF335]

I am not aware of what the Kombi is, actually, but I did not do any coding for speed. The speed is collected from wheel sensors, so the speedometer etc. is not affected by the LSD.

Does anyone know if the engine uses the RPM/speed/gear relationship to calculate anything? Perhaps this needs to be reprogrammed for everything to work properly? In general, the car is absolutely fantastic with this ratio and I don't perceive any issues other than this.

The car has an MHD tune, but this did not change before/after the LSD swap and the issue only appeared after the swap.

Thank you.

[feuer]

I know how speed data is collected, is from Abs sensors. Try coding the Kombi for true speed. I'm not sure how is related with RPM-speed-gear but is how DME knows what gear the manual transmission is in. There isn't sensor on the transmission. I don't have other ideas. Hopefully you will sort it out quickly.

[RSL]

Wouldn't hurt to tell the DME the correct final drive ratio. Luckily, these only work on MT, but you'll need an unlocked bin if MHD doesn't already have it as a flash-time option. Kombi coding may also work or both things may need to be done.

[RocketSurgeon]

Do you know how to use NCS Expert?
There are some cruise control settings in the DSC module that likely need to be coded. I think I have .TRC files from both a manual and automatic N54. I'll look through the files to see what differences exist based on final drive ratio.

[SF335]

Thanks everyone. MHD doesn't have an option to change gear ratios. I have done coding with NCS Expert before but I thought that the gear ratio programming wasn't accessible. Does anyone know of this is possible with NCS Expert?