[outofphase]

Car is a 2014 335i xDrive 8AT, FBO E30, and has 55k miles. Was at Great Lakes Dragaway (1/4 mile track) the other night testing my car after flashing XHP. Car performed no better than it had before with the stock transmission tune and was seeing 60' times in the 1.8-1.9 range. I increased the "Launch Torque" (without touching the "Torque Scaling After Launch" slider) by 20%, and the car launched HARD and felt great but bogged horribly on the 1-2 shift. I then increased the "Torque Scaling After Launch" slider by 20% so that it matched the Launch Torque percentage.

This time the car revved up past 3k RPMs (it had never done that before) and then the converter "let go" (in other words, despite my foot on the brake pedal the car rolled forward) and I got a Drivetrain Malfunction warning. Pulled off the track and turned the car off to let it cool down.

Did a quick scan and got these two codes:

48068C (DSC) transfer case - clutch temporarily shut down, possibly overheating. BMW fault code lookup says, "Clutch control temporarily reduced by transfer case control unit. This measure avoids the clutch overheating. There may be customer complaints concerning the all-wheel control (traction). No repair measures required (self-healing in same ignition cycle possible)."

440117 LMV_FR No description available. BMW fault code lookup says, "Possible fault causes:
- Excessive thermal load on the clutch of the transfer-case servomotor.
- Excessively high thermal load of the transfer-case servomotor.
- Excessive delay in starting procedure.

Some things to note:

- After the XHP flash, I drove the car gently and normally for 50 miles as the manual recommends.

- Did 6 runs. I waited 20-30 minutes between each run to let the car cool down.

- The car shifts sluggishly in general, seems even more so after the XHP flash, though that could be a placebo effect.

- BMW of Elmhurst performed a transmission fluid change a few months ago, but reused the original filter, assuring me it would be fine. Which has me worried that it's NOT fine and that there may be a leak. Of course, I can't check as there's no dipstick and I don't have the time/tools to check the correct way.

I'm not suggesting AT ALL that this is XHP's fault. My guess is user error, or I was too aggressive with the torque adjustments. Taking the car to a trusted indy mechanic later this weeks, but what do you guys think? Is my transmission on the way out? Also, does anyone know what the "Torque Scaling After Launch" slider in XHP actually does? The manual doesn't really explain it clearly and I can't find an answer on the forums.

[doodlebro]

FWIW the app allows that customizability. I don't think it would be too far to say this is xHP's fault. That said, they're not going to cover anything that breaks. Definitely makes me weary to purchase as I'd like a bit of safety built in, not a possibility that I grenade my transfer case.

[Munchi435i]

Anytime you modify your car past stock settings you knowingly run the risk of damaging your car.

Although XHP should give better instructions on how to use some features, it's still up to the end user whether they want to use their car as a guinea pig to use a new feature.

Taking it to the race track to test it where there is maximum tracking due to a prepared track might of not been the ideal place. But if I'm not mistaken x-drive has been know ton have transfer case issues so that could also be a contributing factor.

[gx5_027]

Any update on this OP?

[EDWYER]

Subbed.

[n55david]

Yeah, any update?

[outofphase]

Hey folks, sorry for the delay on the update. Car is seemingly running strong. No fault codes stored and no new ones have popped up. Shifting is still sluggish but it was like that prior to the XHP flash.


My (uneducated) guess is that I was too aggressive with the torque settings. Regardless, I went ahead and ordered a transmission service kit and I'm having my indy shop change the fluid (AND the filter). I'll keep y'all posted.

Originally Posted by Munchi435i

Anytime you modify your car past stock settings you knowingly run the risk of damaging your car.

Although XHP should give better instructions on how to use some features, it's still up to the end user whether they want to use their car as a guinea pig to use a new feature.

Taking it to the race track to test it where there is maximum tracking due to a prepared track might of not been the ideal place. But if I'm not mistaken x-drive has been know ton have transfer case issues so that could also be a contributing factor.

For sure. I've accepted the risk. Trailering it to the track now and it's no longer my daily, so if it blows up, it blows up! I just hate not knowing if something's wrong or not.

By the way, anybody have any idea what the "torque scaling" slider does?

[gx5_027]

Originally Posted by outofphase

Hey folks, sorry for the delay on the update. Car is seemingly running strong. No fault codes stored and no new ones have popped up. Shifting is still sluggish but it was like that prior to the XHP flash.


My (uneducated) guess is that I was too aggressive with the torque settings. Regardless, I went ahead and ordered a transmission service kit and I'm having my indy shop change the fluid (AND the filter). I'll keep y'all posted.

For sure. I've accepted the risk. Trailering it to the track now and it's no longer my daily, so if it blows up, it blows up! I just hate not knowing if something's wrong or not.

By the way, anybody have any idea what the "torque scaling" slider does?

No idea what it does - but the Bryan from Kies Motorsport set his to 25% (for both settings). No reported issues on his end, that we know of. He is xdrive and 8AT, bm3, ps2 (pwg, I believe). So, I bet a lot of people will just do that, even if it's not the safest! I have, but haven't tried LC yet. Having too much fun shifting through the gears. I almost think xhp has slown down the comfort shifting speed. Perhaps on purpose to make the sport and sport plus settings seem even faster? Maybe it's all in my head though - but, comfort seems sluggish, with a noticeable delay between shifts when using paddles, and I never ever had that experience or perception before.

[McLaren720s]

Originally Posted by outofphase

By the way, anybody have any idea what the "torque scaling" slider does?

That’s probably a question you want to ask BEFORE using it?

From XHP manual

“The amount of boost/torque your car is allowed to build while the brake is depressed is setup with the "Set Launch Torque" slider. After releasing the brake the Car tries to manage torque and traction along programmed presets which can be tuned up and down with the "Torque Scaling After Launch" slider. 0% is the factory setting and is optimized for stock cars. Tuned cars may need different settings.”

[outofphase]

Originally Posted by f32_027

No idea what it does - but the Bryan from Kies Motorsport set his to 25% (for both settings). No reported issues on his end, that we know of. He is xdrive and 8AT, bm3, ps2 (pwg, I believe). So, I bet a lot of people will just do that, even if it's not the safest! I have, but haven't tried LC yet. Having too much fun shifting through the gears. I almost think xhp has slown down the comfort shifting speed. Perhaps on purpose to make the sport and sport plus settings seem even faster? Maybe it's all in my head though - but, comfort seems sluggish, with a noticeable delay between shifts when using paddles, and I never ever had that experience or perception before.

Interesting, after this transmission service I'll mess around with it some more. Super happy I found this track -- I was there on a FRIDAY EVENING and it was practically dead. If I'd wanted to hot lap the car I could've easily gone 20+ times in the short time I was there

Also, my experience has been the same re: comfort mode, however the sluggishness is present for me regardless of mode and regardless of map (stock, XHP 1-3, or BM3's transmission flash), which is a bummer. I remember when I first coded 2TB (when the car was stock) the shifts were LIGHTNING quick. Really hope I'm not murdering my transmission.

[EDWYER]

Originally Posted by McLaren720s

That’s probably a question you want to ask BEFORE using it?

[outofphase]

Originally Posted by McLaren720s

That’s probably a question you want to ask BEFORE using it?

From XHP manual

“The amount of boost/torque your car is allowed to build while the brake is depressed is setup with the "Set Launch Torque" slider. After releasing the brake the Car tries to manage torque and traction along programmed presets which can be tuned up and down with the "Torque Scaling After Launch" slider. 0% is the factory setting and is optimized for stock cars. Tuned cars may need different settings.”

I read that actually before altering the settings, but come on, the manual is incredibly vague! The "Launch Torque" slider I understand perfectly, but "torque scaling"???

"After releasing the brake the car tries to manage torque and traction" -- okay, that still doesn't explain what the percentage value actually means or affects!

My frustration isn't towards you, btw, it's towards the wording in the manual

[outofphase]

Update for whoever’s wondering:

This was 100% user error! Also I need new brake pads.

Luckily I had the failure on in-car video finally watched it. I’d looked through the datalog and couldn’t figure out how I overrevved so dramatically during the LC procedure. But looking at the video, right before the revs go crazy, the car lurches forward slightly.

I was able to recreate it in the pits last Sunday.

Basically, my brake pads are pretty worn down and/or I may need new fluid or something else is going on.

I engaged launch control and simply wasn’t pressing down hard enough (though I WAS pressing down very firmly as I have many, many times) — the car lurched forward, and when that happened I slammed on the brakes to try to keep from redlighting — well the TCU assumed I’d launched, and released the rev limiter. Revs go way past 4k, error error error.

I’m horrible at explaining this, sorry.

TL;DR — I wasn’t using the might and fury of a viking warlord to hold the brake pedal down during LC, so the brakes didn’t hold and the TCU thought I launched, disabling the LC limiter and allowing me to nearly blow up my transmission. NOT XHP’s fault. I’m an idiot and also need to service my brakes.

I still don’t understand exactly what the torque scaling slider does though.

[meltbox]

A bit late but torque scaling is essentially how fast the car allows itself to ramp up to 'max torque' which is the engine's full output capability. This exists partially to prevent drivetrain shock and partially to prevent a sudden wave of torque from breaking traction immediately after launch.

Also I have no idea why they didn't change the filter for you. Its like a $100 part and really easy to swap. While I'm here reviving did the trans behave any better after the second fluid swap with filter?