Launch Control and No Lift Shift Configuration

[Steve @ VersaTune]

For those who are unfamilliar with Launch Control and No Lift Shifting, here is a quick overview of how it is implemented in Versatuner and how to customize it for your vehicle.


Stock rev limiter bahavior (NLS/LC disabled)

The stock rev limiter is set to 6700 RPM under normal operating conditions. Under certain conditions like stuck throttle in neutral or certain temperatures, it is set to 5500. When the engine RPMs hit 6700, the ECU cuts fuel for a short duration. If RPMs drop below 6700 and the over rev fuel cut timer is expired, then normal fueling resumes. Normal fueling will not resume until the RPMs drop below 6700. These non-LC/NLS rev limiters are set in Tune Editor like the other tables.


The use of Launch Control/No Lift Shift allows three different rev limits based on clutch position, vehicle speed, and accelerator pedal position. Launch Control/No Lift Shift is enabled and configured in Tune Customizer which is accessed from the Settings button on the Home tab of VersaTuner. When you enable Launch Control/No Lift Shift, it enables the default launch control and no lift shift behavior. It can be customized to your preferences using Tune Customizer.


Normal behavior

When the clutch is not depressed, as in normal driving, the normal rev limiter (6700 RPM by default) applies.


Launch Control (LC) rev limit behavior

The default LC behavior is active when the clutch is depressed, vehicle speed is below 9 km/h or 5.6 mph, and the accelerator pedal position is greater than 98%. While these conditions are met, the LC rev limiter will be active (4000 RPM by default). This allows you to build boost at the starting line for harder launches and a short rollout with the revs limited to help with consistent launching. All of these parameters are configurable in Tune Customizer. If all three of these conditions (clutch, speed, APP) are not met, the normal rev limiter or NLS rev limiter will be used depending on clutch position.


No Lift Shift (NLS) rev limit behavior

The default NLS behavior is active when the clutch is depressed and the vehicle speed is greater than the LC speed threshold (9 km/h or 5.6 mph by default). Under these conditions, the NLS rev limiter is active (5000 RPM by default). This allows you to keep the accelerator pedal down while shifting and not over rev the engine. This alllows the turbo to stay spooled during shifts resulting in immediate power in the next gear. The NLS parameters are configured in Tune Customizer.


Please note that both Launch Control and No Lift Shift create significant additional stress on the engine and driveline. Be certain that you have the necessary upgrades to handle the additional stress.

[mituc]

Is it possible (or does it even make sense) to implement LC by controlling the throttle opening rather than cutting the ignition?

[Steve @ VersaTune]

LC uses the built in rev limiter, which uses fuel cut, not ignition cut.

It would require a tremendous amount of code that would require tuning on every car to do it with throttle control.

[Kay2thePea]

Trying to understand how this works, when my accelerator pedal position never seems to register above about 67% on my 2012 mazdaspeed3. Relative throttle position seems to cap out at 77%. How do you ever see a pedal position at 98% or more??

[xbrandino]

Trying to understand how this works, when my accelerator pedal position never seems to register above about 67% on my 2012 mazdaspeed3. Relative throttle position seems to cap out at 77%. How do you ever see a pedal position at 98% or more??

On Gen2 Mazdaspeed 3s the throttle generally maxes around the area you have specified at 67%, you can in theory space the throttle to get some more range out of it, but you won't get any gain from it because the tune already takes this into consideration.

It is normal for the relative throttle position to max around 77-80%, that is WOT on these cars.

The setting for launch control and no lift shift will reference your accelerator pedal position so you will need to put it before your max, which in this case is 67%.

[CrazyCanadian]

Trying to understand how this works, when my accelerator pedal position never seems to register above about 67% on my 2012 mazdaspeed3. Relative throttle position seems to cap out at 77%. How do you ever see a pedal position at 98% or more??

On Gen2 Mazdaspeed 3s the throttle generally maxes around the area you have specified at 67%, you can in theory space the throttle to get some more range out of it, but you won't get any gain from it because the tune already takes this into consideration.

It is normal for the relative throttle position to max around 77-80%, that is WOT on these cars.

The setting for launch control and no lift shift will reference your accelerator pedal position so you will need to put it before your max, which in this case is 67%.

When it comes to APP%. Gen2's don't have pid that shows the 0-100% calculation. It's misleading since the pid you are reading isn't a true 0-100% calculation. That being said, the ECU does calculate APP position from 0 - 100%, you just don't have access to that data on a Gen 2.. So you can use any values you want when it comes to APP command related stuff. If you want to get fancy, log the voltage value that goes from low to high and do the 0-100% conversion calculation yourself. Min voltage would be what you see with your foot off the throttle. Max is what you see with your foot to the flow. Current voltage is where you foot is at.

APP% calculation = ((Current Voltage - Min Voltage)/(Max voltage - Min Voltage))*100

Relative Throttle is a measurement of throttle body blade movement. Key on and Key off the ecu cycles the throttle fully closed to fully open. It logs the min and max voltages. It'll use the same calculation just based on the throttle body sensor voltages. The ECU never commands the throttle 100% open while driving. It would break things if it did. On turbo cars the difference between about 75% and 100% throttle blade position doesn't really effect total power out put. So the ECU caps it's command out around that area..