Unitronic Stage 2 (JB4 stack) Torque Management

Hi all,

Just a quick warning to other that plan to stack both. I've been experiencing torque limitation with the Unitronic Stage 2 ECU flash + JB4 stack. Thanks to wy2sl0 (Matt's) help, we identified that the car is having problems with torque limitations when combined.

This is mostly likely caused by the crazy dense air and cold temperatures we recently had up North.

What to look out for / Symptoms ?
Sudden boost dip and throttle value dip

map4
This even happens in map4 on the JB4 (when it's not adding any boost)
https://datazap.me/u/marc5800/unitronic-stage-map4-10?log=1&data=1-2-3-4-9

https://datazap.me/u/marc5800/unitronic-stage-map4-10?log=2&data=1-2-3-4-9

map6
https://datazap.me/u/marc5800/unitronic-stage-2-map6-19?log=1&data=1-2-3-4-9


As winter is approaching its end, this shouldn't be a problem anymore.


** the weird thing is that after logging numerous times (to the point where I felt bad for the car from doing all these WOT pulls lol), the problem would only occur when the JB4 is connected to a device!

I tried reproducing the problem with the mobile device plugged but not connected and I wasn't able to reproduce the issue.
I tried reproducing the problem with the mobile device plugged in and connected, and it happened again

- Quick note, I also talked to Unitronic since I thought the problem was with the tune. They asked that I log via VCDS. After logging with VCDS, the problem didn't occur either!
(The JB4 was in map0 and OBD disconnected)

I wonder if the JB4 is introducing a slight delay somewhere in the ECU loop, which is forcing a correction/throttle closure. If it was a software torque limitation, wouldn't you see this issue without the JB4 connected, considering you are seeing it on Map 0 AND Map 6?

Try connecting to the JB4 with via hardwire, and not bluetooth, and see if you can reproduce it there. Maybe something with the data transmission via BT is introducing a PID lag on the device.

Jay_Heim said:

I wonder if the JB4 is introducing a slight delay somewhere in the ECU loop, which is forcing a correction/throttle closure. If it was a software torque limitation, wouldn't you see this issue without the JB4 connected, considering you are seeing it on Map 0 AND Map 6?

Try connecting to the JB4 with via hardwire, and not bluetooth, and see if you can reproduce it there. Maybe something with the data transmission via BT is introducing a PID lag on the device.

Click to expand...

Hey Jay,
It could be introducing a slight delay.

This is exactly my thoughts. If it was a software issue when I hooked up the VCDS and completely remove the JB4 (ODB2 disconnected w/ firmware update that adds no boost once disconnected) the car would of had the torque limit issue. Which it didn’t reproduce.

It didn’t show this issue without the JB4 connected.

The JB4 was connected via data cable to mobile phone with OTG cable. It wasn’t connected via BT.


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marc5800 said:

Hey Jay,
It could be introducing a slight delay.

This is exactly my thoughts. If it was a software issue when I hooked up the VCDS and completely remove the JB4 (ODB2 disconnected w/ firmware update that adds no boost once disconnected) the car would of had the torque limit issue. Which it didn’t reproduce.

It didn’t show this issue without the JB4 connected.

The JB4 was connected via data cable to mobile phone with OTG cable. It wasn’t connected via BT.


Sent from my iPhone using Tapatalk

Click to expand...

Hmmmmmm......

Did you ping The Man Himself for his thoughts? There are a bunch of stacked setups out there; I'm sure he would have fixed an issue if he had seen it already.

Jay_Heim said:

Hmmmmmm......



Did you ping The Man Himself for his thoughts? There are a bunch of stacked setups out there; I'm sure he would have fixed an issue if he had seen it already.

Click to expand...

I did but he hasn’t found a possible solution or a definite answer on what’s causing this.

Exactly - I know others stacked with Uni and JB4 or stacked with other tunes. Haven’t heard any of them reporting issues like this tho.

Very weird...


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Do you have that 'direct acceleration tweak' turned on via VCDS?

I'm grasping at straws a bit... This reminds me of an issue I had a few PC builds ago, where a soundcard was introducing massive PID interference and causing RAM latency. I'd end up with a freeze frame where a single value in memory would get stuck and lock the CPU for a split second. Not a big deal with a PC, but that's a huge deal with a car.

Have you tried using a different mobile device?

Jay_Heim said:

Do you have that 'direct acceleration tweak' turned on via VCDS?

I'm grasping at straws a bit... This reminds me of an issue I had a few PC builds ago, where a soundcard was introducing massive PID interference and causing RAM latency. I'd end up with a freeze frame where a single value in memory would get stuck and lock the CPU for a split second. Not a big deal with a PC, but that's a huge deal with a car.

Have you tried using a different mobile device?

Click to expand...

Jay

I do have the direct acceleration tweak turned on, should I consider taking it off?

I only have have 1 compatible mobile device (android) ... unless I pay 40$ for the app on iPhone. Not sure if it’s worth it.

I think you’re on to something tho with the VDCS tweak...


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$0 to try...

Diggs24 said:

$0 to try...

Click to expand...

True!

But the idea of many more WOT logs is a little frightening
I feel like this car is taking a beating!


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marc5800 said:

True!

But the idea of many more WOT logs is a little frightening
I feel like this car is taking a beating!


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Click to expand...

Take the log with a laptop.

Also disable the direct acceleration thing - it was causing me problems after the latest JB4 update was installed, smoothing throttle response. I had crazy AFR spikes mid-pull.

Jay_Heim said:

Take the log with a laptop.



Also disable the direct acceleration thing - it was causing me problems after the latest JB4 update was installed, smoothing throttle response. I had crazy AFR spikes mid-pull.

Click to expand...

Removed the direct acceleration tweak. I’ll see if it makes a difference.

I might try logging with a laptop to see the difference.

These are some good tips Jay, thanks man!
I’ll update this thread


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Is the magic in or is this still on stock IC?

Oldschoolmk7 said:

Is the magic in or is this still on stock IC?

Click to expand...

Still stock IC ... will be installed soon

Temps are still cool over here.
Going from 5 F to 30 F ~


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marc5800 said:

Still stock IC ... will be installed soon

Temps are still cool over here.
Going from 5 F to 30 F ~


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Click to expand...

That is very cold temps to be logging in imo. I would try some 50 degree plus days.

Oldschoolmk7 said:

That is very cold temps to be logging in imo. I would try some 50 degree plus days.

Click to expand...

True it is pretty cold, and at those temps, air is super dense.

But either way, when you go WOT, there shouldn't be a boost dip / drop even if its cold out.