2020 Mustang GT - closing throttle on 3-4 shift - 10r80 - tq red > driver demand

[Justinjor]

So took the shop car to the track for the first time last night. Car is a 2020 Mustang GT with 480 miles on the odometer. It made 440whp on my dyno and first pass down the track it went 11.9@119 as delivered from the dealer.

The only change to the car is E85 in the tank and my quick dyno tune. Stock everything else.

I was aiming for 7400rpm shift points given the power curve but wanted to see what it did with stock shifting schedule first.

On the stock transmission shift schedule everything seemed ok. No throttle closing issues but only ~6800rpm shifts.

Tweaked a few things and got it shifting right at 74-7500 which was ok but on the 3-4 i'm getting tq red >driver demand and the throttle was closing to 35% for a short time.

Any ideas?

Given the very stock nature of the car minus the fuel, I'd like to assume the torque model is basically correct so I'm not sure why the pcm is upset about.

Log and tune attached.

It just seems weird it's only on the 3-4 shift. I haven't found a glaring problem yet but I'm still digging.

Log 1 goes with tune file 4
Log 3 goes with tune file 6

[Ranger Coyote]

Says in your log Trans Protect RPM Limit 7570. I suspect you are running into limits in ECM 6849 under Trans>General>Limits>Limit Initial. Also the polling speed on your RPM is very slow and you are not seeing the actual maximum RPM. Looks like a RPM limit for sure even tho I don't see the smoking gun.


Torque Source: In Gear Limit
Spark Source: Torque Control
Trans Protect Limit: 7570

[Justinjor]

Says in your log Trans Protect RPM Limit 7570. I suspect you are running into limits in ECM 6849 under Trans>General>Limits>Limit Initial. Also the polling speed on your RPM is very slow and you are not seeing the actual maximum RPM. Looks like a RPM limit for sure even tho I don't see the smoking gun.


Torque Source: In Gear Limit
Spark Source: Torque Control
Trans Protect Limit: 7570

Good eye. Thank you!

I'm not sure what happened but the polling speeds are all slow. I just noticed that.

Thank you for pointing it out. Fresh set of eyes is killer

[Justinjor]

Next pass was log 7/file 7. I had already raised that limit initial up to 9000 and now trans protect limit is 7075.

See anything else that looks suspect? I'm going to take a shower and dig over this file again. See if i can reset my brain

[Ranger Coyote]

I think the slow polling is messing with your ability to see correct sources... There is a table that shows what can limit your throttle and it comes down to exhaust temp, turbo fmem, or injector limit look at the pic below

maybe.jpg

[Ranger Coyote]

Next time you log you might try to remove as many channels as you don't need and see if your polling speed improves? Is 330lbs/hr 95% duty cycle on your injectors?

[Justinjor]

Next time you log you might try to remove as many channels as you don't need and see if your polling speed improves? Is 330lbs/hr 95% duty cycle on your injectors?

The entire fuel system is stock. The only physical change to this car outside of how it was delivered from the factory is the fact it has E85 in the tank. I have not added or removed anything from the car.

It's currently using 85% DI blend above 7k rpm.

The stock tables are set to 90% and I ASSumed it would automatically blend down if it's running out of DI capability. It is on E85 so perhaps its maxing out the DIs and shutting the throttle as its hitting the limit of those?

I wonder if I set the max blend above say 6000 to 80% that was it starts to use the PIs ahead of the DI limit?

The 7k trans limit RPM is interesting. Not sure where that comes from

[Justinjor]

I think the slow polling is messing with your ability to see correct sources... There is a table that shows what can limit your throttle and it comes down to exhaust temp, turbo fmem, or injector limit look at the pic below

maybe.jpg

Hmm. Ok. I will look into that. Would be nice if the ETC source said Injector limit so I knew what the computer was actually thinking and why it decided to close the throttle only on the 3-4 shift

[superman07]

do you even have enough pump for e85.

[Justinjor]

do you even have enough pump for e85.

On a bone stock car with 0 performance modifications? I believe so. Fuel trims are perfectly in line, fuel pressure isn't dropping. No reason to suspect the stock fuel pump is at its limits

[Justinjor]

Fixed!

Did a handful of back to back pulls today and no issues. I believe the issue was rpm element limit and a couple other limiters that I had raised, but not raised enough to consistently allow 7500+ rpm shifts.

Also fixed the polling in the log and it's MUCH more responsive now.

Added the fixed file in case anyone wants to compare file 7 to 9 to see what needed to be changed.

7600rpm shifts no problem

fixed.jpg

[small tuner]

can you post the log?

[Justinjor]

can you post the log?

The only log I have with the fix is about a 2 hour drive log which is pretty big. I'll try and get a smaller one later

[LastPlace]

The only log I have with the fix is about a 2 hour drive log which is pretty big. I'll try and get a smaller one later

you can trim any portion of a log


Log File > File Exporter > Visible range ( use your mouse wheel or the zoom feature to choose that)

[Justinjor]

you can trim any portion of a log


Log File > File Exporter > Visible range ( use your mouse wheel or the zoom feature to choose that)

well that's super handy. Ty!

Log attached. Happy shifting now

[Ranger Coyote]

I don't wanna hijack with unrelated stuff, but how do you add a blank line between groups of things you are logging in the vcm scanner?

[LastPlace]

Right click on the channel list and you’ll see where it says move things up and down just move things down to make a space

[small tuner]

well that's super handy. Ty!

Log attached. Happy shifting now

how to get ride of shift modulation and spark reduction TQ source between shifting. have you notice that

[Justinjor]

how to get ride of shift modulation and spark reduction TQ source between shifting. have you notice that

I have not messed with any of that yet. Given that the transmission is stock, I think it's wise to leave the factory torque management active between shifts so this thing (hopefully) lives a long and fruitful life