'17 F150 6R80 Trans brake throttle closing issue

[Modern Muscle]

Hello All,
Working on my 2017 F150 XL SCSB 5.0L w/ 6R80. Truck is NA right now with the following bolt-ons. CAI, '18 GT Intake, cat-back exhaust and built trans with Circle D triple disc 3,200 stall convertor. I have the truck running pretty good and trans is shifting great. Just did the trans brake set up using the two relays using the SSD and SSC circuits. Made the adjustment in the tune to low/reverse max VSS setting and T-brake is holding perfectly. When I get up on the trans brake ETC Source goes to TQ Red<Driver Demand and limits RPM to around 2,000 rpm. Throttle closes down to around 20%. I had the same issue when trying to do a burnout. Only way I found around this was putting the truck in dyno mode through the tune and it still doesn't seem consistent on ability to do a burnout. I tried upping inferred movement to 8,000 rpms and this didn't help. Has anyone done a trans brake set-up on a 15-17 F150? What did you have to change to make it work? Seems to be more safety checks on the Gen2 stuff than the Gen1 mustangs I've done. I'll post tune and log later, unfortunately I'm on my desktop now and don't have the files.

[veeefour]

Post a tune, will look into it.

[Modern Muscle]

Here is the tune and a data log. I changed inferred movement back to stock and upped non-shift limit. Haven't tested this tune yet.

[veeefour]

Try zeroing those:

image.png

[Modern Muscle]

I'll give that a try. Thanks Veeefour!

[bigdog347]

I'll give that a try. Thanks Veeefour!

Curious if that worked.
I have a similar issue on a 2013 f150 5.0l and am tired of TC kicking in during burnouts. I couldn't find those tabs in my tune but I found some other air limits I may try modifying.

[murfie]

25-30% lean fuel trims, seems like its still learning the ethanol content in the tank, and you are tring to get it up on a transbrake and maybe do burnouts.
infered Flex fuel is green emissions friendly stuff, done on the cheap with out a direct sensor by Ford. Using ethanol as a high octane fuel should have a dedicated tune for the blend you are using.

[Modern Muscle]

Last night had a chance to try the changes Veeefour recommend. This prevented the ETC source from going to TQ Red<Driver Demand but throttle was still limited to around 20%. Once your floor the pedal it will go to 85% throttle and then will quickly roll it back to around 20%. All source values appear normal.

Murf I understand what you are saying, but why would this limit throttle opening?

[veeefour]

Last night had a chance to try the changes Veeefour recommend. This prevented the ETC source from going to TQ Red<Driver Demand but throttle was still limited to around 20%. Once your floor the pedal it will go to 85% throttle and then will quickly roll it back to around 20%. All source values appear normal.

Murf I understand what you are saying, but why would this limit throttle opening?

Post a log, will figure this out.

[Modern Muscle]

See attached data log.

[veeefour]

Need to log a lot more in my book. Use this list

[murfie]

You should atleast let it learn before logging and tring to tune for performance, is all im saying.


My guess is this airmass limiter, or something to do with driver demand> launch mode> OSS max/min tables and pedal map ratio.
Wording in the description is for 10R80 transmissions, but its a snip direct from the tune you posted.

Launch mode.png

[Modern Muscle]

Did some more testing today. See attached logs. Tried upping the Launch Air mass percent as Murf suggested and even tried disabling it by setting disable speed to 0 mph. No luck so far. Also tried disabling TQ management clip. No matter what I try it holds RPM to 2,000 when I'm on the t-brake.

[murfie]

None really tell you anything other than ETC torque isn't allowed over 181 lb-ft. WOT pedal "ignores" driver demand torque and it's only following desired airmass to airmass the engine is actually flowing.

Log
-desired airmass arbitration source
That should tell you what's limiting desired airmass. It could be transmission tq reduction or any of them.

The only other option is to make it think the engine is flowing less airmass for the load via SD or torque tables. That way its under the limit and opens the throttle more.
You said dyno mode gets around it. It might not be viewable in the logs or accessible in the tune and be something ABS, Traction Control, or Advanctrac features are not liking. You shouldn't have to touch the brake pedal at all, and log #6 did show some tire movement like you are brake boosting and not trans braking.

[veeefour]

You are hitting cyl press limit, however briefly. This might be enough to kick your spark out of torque control.
And if your arbitration is set like that the way it acts might be perfectly normal.

You want your spark to stay in borderline or torque reduction, MBT/Base should not be used under this condition.
The moment it breaches cyl. press limit, VCT drops from OP to best fuel economy.

[Modern Muscle]

Hello Murf, thanks for the reply. I will try to log desired airmass arbitration source. Dyno mode doesn't get around this issue, only fully disables traction control. It's still in dyno mode when I'm doing these test. Also the movement you are seeing is sometimes the trans brake doesn't grab right away and it almost bumps up like using a bump box, then grabs. I think this only happens in sport mode for some reason, I have to do more test. I was trying to tackle one issue at a time. I have another data log I'll post later where I'm power braking it and it does allow more throttle opening with the tire spinning, but other times it wouldn't do a burnout and closed the TB. I'm wondering if it is holding the throttle back at 0 mph and when it sees wheel speed it allows the throttle to open.

Thanks for your input to Veeefour. I can try raising the Cyl press limit table to avoid hitting it.

[Modern Muscle]

Here is the log doing a burnout.

[murfie]

Old log, not a lot to see in it. Only thing it shows is the MAF sensor is picking up turbulence.

Are you using the third relay to break the LPC circuit for max line pressure? You don't have DTC's for doing that disabled. P0748 and P0960, 961, 962. People report creep and brakes not holding well on stock transmissions with out it.

new TRANSBRAKE.jpg

[Modern Muscle]

Hello Murf. It is a log I did a month or so ago when trying to get the truck to power brake. It was before I installed the trans brake stuff. No I didn't do the third relay to break the LPC as my trans is built with the updated Raybestos clutches and billet intermediate shaft. I also have a Circle D triple disc convertor. It holds most of the time. My truck is a Gen2 F150 and it doesn't have a MAF sensor.

What I was trying to show with the previously attached log is once the tires were spinning and showing MPH, it looks like the throttle would open more.

[murfie]

Correct I ment MAP sensor*. Log did not have OSS or vehicle speed. I can not see tire movement in it. I can only make a guess based on the RPM.

MAP sensors dont usually have turbulence like this.

MAP Turbulance.jpg