MT - de-tuned throttle map when clutch is pressed in (disengaged)

[slugg#3]

This is interesting. Is this the same feeling with putting into reverse going uphill from a dead stop?

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[zpower86]

Check out the two throttle tables I posted above.

Is the "Neutral" throttle map triggered when the clutch is pressed in or when the shifter is not in gear?

 

[zpower86]

Updated the thread title for clarity.

 

[razorlab]

Is the "Neutral" throttle map triggered when the clutch is pressed in or when the shifter is not in gear?

Given those two maps mirror your experience, I would probably say yes.

 

[zpower86]

Given those two maps mirror your experience, I would probably say yes.

You're saying the "Neutral map" is only based on clutch position and not gear selection. Got it.

This is good, supporting evidence -- thank you for posting it. I would characterize this behavior as an "Issue". I'm not sure how to go about it, but I'd like this to be brought to Toyota's attention so they can evaluate and potentially fix it.

 

[razorlab]

You're saying the "Neutral map" is only based on clutch position and not gear selection. Got it.

This is good, supporting evidence -- thank you for posting it. I would characterize this behavior as an "Issue". I'm not sure how to go about it, but I'd like this to be brought to Toyota's attention so they can evaluate and potentially fix it.

It might be both. Either out of gear (neutral) or with clutch depressed and not activating the top switch (also neutral)

 

[mdpalmer]

I dont know what else affects the actual throttle opening, but if the only variables are clutch status, requested throttle, and vehicle speed, the second table razorlab posted could be edited. Just copy the requested throttle values across the entire table and I would expect the "issue" to be resolved.

It may not be clear to us why that table is scaled the way it is, or if its actually an error on BMW/Toyota, that table may be the result of other requirements on modern cars for emissions or efficiency reasons.

Which is why I asked if anyone has a better understanding of the iMT system, its not just rev matching but all the other quirky stuff going on in the background with this car.

I have also experienced the symptoms OP i haven't been able to reliability repeat them though i will try your suggestions.

You're saying the "Neutral map" is only based on clutch position and not gear selection. Got it.

This is good, supporting evidence -- thank you for posting it. I would characterize this behavior as an "Issue". I'm not sure how to go about it, but I'd like this to be brought to Toyota's attention so they can evaluate and potentially fix it.

 

[Mf1ve]

On my '24, the point at which the throttle map switches over is at roughly 1-2 inches of travel up from the floor, and far enough below the clutch bite point that there is room to let the pedal up a bit after the map switches and before the clutch bite begins. It otherwise acts just as OP describes. I'm planning to look at this a little more though i do not have the tools to look at maps, etc. (stock, locked ecu).

Edit: not 1/2 pedal travel, more like 1 to 2 inches up from the floor.

 

[Mf1ve]

Definitely a switch or sensor on the clutch master.

 

[Mf1ve]

The connector faces towards the outside of the car and is easy to touch but difficult to get to.

Kinda looks like a Hall effect sensor. Here's a similar (or the same) part on a BMW:

And per this link, this switch does interact with a magnet on the clutch master cylinder piston - and acts as the clutch safety interlock for starting the car. The link is about spoofing the switch signal to allow for starting without depressing the clutch when desired (via a second switch). It does mention that the clutch switch/sensor supplies more than one signal, " Other features like cruise control and automatic idle-up are unaffected since they use a different signal on the clutch switch."

 

[Deutsches_Sushi]

I found an issue with MT Supra's which I wanted to bring to everyone's (any Toyota's) attention. I have not seen anyone discussing this. There are threads about the clutch cdv and clunky shifting, but this topic is a little different.

There is a "Reduced sensitivity" throttle map when the clutch is disengaged (clutch pressed in) versus the normal/baseline throttle map (clutch pedal out). When you have the clutch pressed "In" and slowly lift the pedal, just as you get close to the "Clutch engagement point", the throttle map instantly changes to 'normal' which abruptly increases the RPM/power just prior to the clutch disc catching.

You can test this on any MT vehicle. With the car in neutral, press clutch in, and REV and hold at 2000 rpm, then slowly let clutch out. Your RPMs will shoot up dramatically. The inverse happens if you start with the clutch out. This is repeatable any time, in any gear and in any drive mode for all 2023-2024 MT Supra's.

I think this is a design flaw that needs to be corrected by Toyota for 3 reasons. (1) It makes the car feel clunky during normal up and down shifts since the car adds throttle right at the last second. (2) It is very difficult to set a consistent RPM prior to a launch from zero. This ultimately makes your launches inconsistent in a competitive environment. (3) The throttle blip needed during a heal-toe downshift is insufficient (since the clutch is in). This results in improper/difficult rev matching (when auto rev matching is turned OFF).

Has anyone else identified this problem? Please comment if you have.

Is there any chance Toyota/BMW could fix this on a recall?

Im glad that im not the only one noticing this, this was my first impression when I turn off iMT, executing toe heel myself, I had to use ALOT of throttle pedal movement, my issue is also that the moment I clutch in, it feels very sloppy on the throttle sensitivity, I just want that instant blip,
I thought by coding in Sport+ would help me with the throttle sensitivity, but it made no difference.

Don't know if there is a way to remove this feature, or to bypass the clutch signal that goes to the DME? or unlocking the dme and have a tuner to look at this? MHD or BM?

 

[razorlab]

Don't know if there is a way to remove this feature, or to bypass the clutch signal that goes to the DME? or unlocking the dme and have a tuner to look at this? MHD or BM?

If anyone with a MT has a femto'd ecu, on bootmod3, I would be happy to take a look at the ROM if it helps the community. Talking about the OEM ROM, not the tuned one, so no worries about me seeing any tuners work. DM me if interested.

 

[Mf1ve]

If anyone with a MT has a femto'd ecu, on bootmod3, I would be happy to take a look at the ROM if it helps the community. Talking about the OEM ROM, not the tuned one, so no worries about me seeing any tuners work. DM me if interested.

I hope you get the chance to look at it - fixing this through an unlock is a valid option. It would be fantastic and a great help to the racing community if Toyota updated it themselves, but I am not optimistic right now that they will offer it.

 

[razorlab]

Okay, someone here was kind enough to provide me with their 2023 MT stock ROM.

Overall, when comparing to a 2023 Auto ROM, almost everything is identical. There are some scaling changes and obviously gear ratio changes and such. The throttle mapping for the 6MT maps are identical in both ROMs.

However, I did find these two tables that are pretty interesting. Obviously the clutch-in table is not used on a Auto Supra. This could be the table that flares the RPM up with the clutch switch.

 

[Mf1ve]

Awesome, good find.

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