Confused about XHP and torque limits and Femto unlock

[ArmenLS1]

So i've been datalogging alot lately and my last log on Stage 2 93 OTS showed some throttle closure and torque limits exceeding target. I did share the log with PTF and they confirmed that some limits were being reached and TCU flash would take care of that.

Here is the log that that shows some throttle closure. https://www.bootmod3.net/log?id=652fee2cc090c6b690f24123

Naturally I reached to XHP as well for details, etc... I asked some questions and specifically around the Femto unlock. Now they mentioned in the first reply that depending on how Femto unlocks the DME, the torque limits could be ignored or not ignored.

"No, the Femto Unlock is on the DME. XHP only communicates with the transmission. If your Femto Unlock included the option "ignore transmission limiters", then some features like Launch Control do no longer work correctly. Also torque limited set by the xHP app, will be ignored by the DME."

I was never aware of choices when it came to Femto unlocks or different options other than remote start. I see a lot of high HP guys with aftermarket turbos, E50 custom tunes, making lots of power but no transmission tune and never complaining about torque limits.

Is anyone here with Femto unlock running XHP on their car because of torque limits and what's their experience? I'm more interested in the limits than harder shits and clamping force. That's the only thing the YT videos talk about.

Sponsored

 

[baagel]

Custom DME tunes can set different torque limits. I think because you're using an OTS tune, they're basically telling you to get a custom tune or use xHP as a solution for the torque limiter.

 

[ArmenLS1]

Custom DME tunes can set different torque limits. I think because you're using an OTS tune, they're basically telling you to get a custom tune or use xHP as a solution for the torque limiter.

Yes i've read something about that. Basically a custom tune is tricking the system. Where as XHP actually tightens up line pressure and other variables and increases the limit

Which would be a better direction?

1: Get custom tune on DME, tuner raises torque limits, safer on engine than OTS map, harsher on transmission?

2: Stick with OTS maps, get XHP, Stage 1 transmission flash just for limits, safer on transmission, harsher on motor.

Is my logic flawed?

 

[razorlab]

Why guess? Log Torque Limit and Fill Limit and find out exactly what is happening.

Also, the only throttle angle change in your log is during the gear change, which is normal.

You also need to log load actual and load target.

 

[ArmenLS1]

Why guess? Log Torque Limit and Fill Limit and find out exactly what is happening.

Also, the only throttle angle change in your log is during the gear change, which is normal.

You also need to log load actual and load target.

What are the exact RAM channels you're referring to? There are a lot that are similar.

 

[razorlab]

What are the exact RAM channels you're referring to? There are a lot that are similar.

RAM Rel. Fill Limit (Flag)
RAM Torque Limit (Flag)
RAM Torque Limit Active (Flag)
RAM Load (Actual)
RAM Load (Target)

 

[ArmenLS1]

RAM Rel. Fill Limit (Flag)
RAM Torque Limit (Flag)
RAM Torque Limit Active (Flag)
RAM Load (Actual)
RAM Load (Target)

Out of curiosity, is that data log snip it from a 1/4 mile run or highway pull in Mexico?

 

[razorlab]

Out of curiosity, is that data log snip it from a 1/4 mile run or highway pull in Mexico?

On a turny boi racetrack.

 

[baagel]

Yes i've read something about that. Basically a custom tune is tricking the system. Where as XHP actually tightens up line pressure and other variables and increases the limit

Which would be a better direction?

1: Get custom tune on DME, tuner raises torque limits, safer on engine than OTS map, harsher on transmission?

2: Stick with OTS maps, get XHP, Stage 1 transmission flash just for limits, safer on transmission, harsher on motor.

Is my logic flawed?

No matter how you remove the torque limiters, higher torque is putting more stress on the trans. You can ask the tuner to limit the torque to whatever values you want.

A custom tune will generally be better/safer than an OTS tune.

 

[zrk]

OTS

Here's your problem.

 

[kfer]

Is anyone here with Femto unlock running XHP on their car because of torque limits and what's their experience? I'm more interested in the limits than harder shits and clamping force. That's the only thing the YT videos talk about.

I have a regular Femto Unlock with xHP and have no problems with torque limitations.
Femto didn't specify an option for "ignore torque limits". And to be honest, I thought the ignoring happens in the logic of the tuning.
My friend has an MHD OTS on his M340i and the limits (>550Nm) are simply ignored. He spoke to MHD and they confirmed it ( other limitations e.g. gear switch are not ignored).

The transmission limiter is somewhere in the 550 Nm range, but the transmission has no idea how much torque you're making, so here we're talking about the "torque at clutch" value ( DME->TCU).
This value should be the actual value that your engine delivers, but this is not necessarily the case with a tuned one.

There are (as far as I know) 3 options:
1. the tuner sends values below 550Nm but significantly more is made (this is how MHD OTS works on my Z4. The car makes way more then 600Nm, but the "torque at clutch" is only max. 530Nm) - this is the worst solution
2. the tuner ignores the feedback from the gearbox in order to stay below 550Nm (this is how MHD OTS works on the M340i). This is better, because at least the transmission knows how much torque is present. But it can't do much with it, because the TCU mapping is made for normal use (550Nm), so I gues there are no suitable line pressures for 700+ Nm.
3. tuner sends the correct values, ignores nothing and you have a TCU tune (e.g. xHP). This is the best way.

The side effects with xHP ( I mean only the line pressure) :
Nr. 1. won't work with xHP because of the faked values. xHP will never be able to apply the right line pressures
Nr. 2. xHP can apply the correct values, but you cannot set lower limits per gear, because DME ignores the TCU's request. This is exactly what happened to my friend, he wanted to set 500Nm for gears 1 and 2 but nothing happened.
Nr. 3. works perfect with xHP.

Why do you think you have a torque limitation issue ? Your log looks good.
Your "torque at clutch" is only at ~600Nm, but according to virtual dyno your car makes about 460-470 HP/650-660Nm.

 

[ArmenLS1]

I have a regular Femto Unlock with xHP and have no problems with torque limitations.
Femto didn't specify an option for "ignore torque limits". And to be honest, I thought the ignoring happens in the logic of the tuning.
My friend has an MHD OTS on his M340i and the limits (>550Nm) are simply ignored. He spoke to MHD and they confirmed it ( other limitations e.g. gear switch are not ignored).

The transmission limiter is somewhere in the 550 Nm range, but the transmission has no idea how much torque you're making, so here we're talking about the "torque at clutch" value ( DME->TCU).
This value should be the actual value that your engine delivers, but this is not necessarily the case with a tuned one.

There are (as far as I know) 3 options:
1. the tuner sends values below 550Nm but significantly more is made (this is how MHD OTS works on my Z4. The car makes way more then 600Nm, but the "torque at clutch" is only max. 530Nm) - this is the worst solution
2. the tuner ignores the feedback from the gearbox in order to stay below 550Nm (this is how MHD OTS works on the M340i). This is better, because at least the transmission knows how much torque is present. But it can't do much with it, because the TCU mapping is made for normal use (550Nm), so I gues there are no suitable line pressures for 700+ Nm.
3. tuner sends the correct values, ignores nothing and you have a TCU tune (e.g. xHP). This is the best way.

The side effects with xHP ( I mean only the line pressure) :
Nr. 1. won't work with xHP because of the faked values. xHP will never be able to apply the right line pressures
Nr. 2. xHP can apply the correct values, but you cannot set lower limits per gear, because DME ignores the TCU's request. This is exactly what happened to my friend, he wanted to set 500Nm for gears 1 and 2 but nothing happened.
Nr. 3. works perfect with xHP.

Why do you think you have a torque limitation issue ? Your log looks good.
Your "torque at clutch" is only at ~600Nm, but according to virtual dyno your car makes about 460-470 HP/650-660Nm.

There were a few variables in the log that I misinterpreted. I also got confirmation from PTF that the Femto unlock does remove the limitations.

I will go with a custom tune sooner or later. Car season where I live is coming to an end so it's too late and probably a bad idea to do tune revisions in super cold and wet weather. Til next year.

 

[kfer]

I also got confirmation from PTF that the Femto unlock does remove the limitations.

That's interesting, thanks for the info!
But does it actually mean that a BMW/Supra before 2020/6 without Femto Unlock has a factory torque limitation and that with Femto Unlock has none, so a tuning with e.g. 650Nm will work for the femto unlocked but don't for the old one? Or it can work if the tuning can eliminate the torque limits differently.
To be honest I've never tried to set Torque Limits in the xHP, but if it's true then it won't work for me anyway.

 

[ArmenLS1]

That's interesting, thanks for the info!
But does it actually mean that a BMW/Supra before 2020/6 without Femto Unlock has a factory torque limitation and that with Femto Unlock has none, so a tuning with e.g. 650Nm will work for the femto unlocked but don't for the old one? Or it can work if the tuning can eliminate the torque limits differently.
To be honest I've never tried to set Torque Limits in the xHP, but if it's true then it won't work for me anyway.

So i'm never saticefied with just one answer. I had also reached out to Femto via Insta and asked them the same question.

"Hi, we don't know if this option is included in bm3 customrom, you need to ask their support. We are not adding anything extra on top of customrom."

"We can't confirm it because we don't know what inside bm3 customrom code.
Their api just giving us the file and we are uploading it"

So someone somewhere is removing the torque limitations. This is all I can establish at the moment, lol. It definitely stems from the tune. If you look at the past release notes on OTS maps PTF always posts things like" Torque limitations adjusted", etc.. so it stems from the tune.

Ex...

 

[razorlab]

So i'm never saticefied with just one answer. I had also reached out to Femto via Insta and asked them the same question.

"Hi, we don't know if this option is included in bm3 customrom, you need to ask their support. We are not adding anything extra on top of customrom."

"We can't confirm it because we don't know what inside bm3 customrom code.
Their api just giving us the file and we are uploading it"

So someone somewhere is removing the torque limitations. This is all I can establish at the moment, lol. It definitely stems from the tune. If you look at the past release notes on OTS maps PTF always posts things like" Torque limitations adjusted", etc.. so it stems from the tune.

Ex...

AFAIK the OTS maps have the limitation upped/removed. If you start from scratch, not OTS (custom tuning) then you need to up/remove them in the rom.

There are 20+ limitation tables. Some of them make the car up/down shift crazy aggressive. I actually had my Supra shifting insanely aggressive before I even had xHP. xHP by itself is much less aggressive.

FYI, @kfer is incorrect about the torque limit. It is 650nm, not 500nm.

Sponsored