Transmission Control

Transmission Control

Transmission Control

The Transmission Control function is able to control multiple styles of transmission. Some conventional automatic transmissions such as the Toyota A340e, pneumatically actuated sequential transmissions, as well as pneumatically actuated specialist transmissions such as made by Lenco and Liberty Gears. 



Shift Settings

Auto Shift Option

Allows the tuner to select whether the ECU will trigger gear shifts to occur when the shift points are reached. 
Typical street cars would have this set to Auto Up and Down.
If you only want to use paddle shifts, then set this to Auto Disabled.
Some circuit racers with paddle shift like to have the transmission automatically shift for them in some circumstances, but have the paddles override. e.g. up-shift at ideal times for ideal acceleration. This can be achieved by setting Auto Shift Option to what the driver prefers as well as enabling the paddles. 
Some transmissions commonly used in drag racing have difficulty down-shifting while the vehicle is moving. In this case, Auto Up is most appropriate. Alternately, select Auto Up and Down but set the down-shift points to 0 vehicle speed. 
In drag race cars with transmissions which can down-shift while moving, Auto Up and Down can be chosen. 

Main Shift Point Variable

This is not available if the Auto Shift Option setting is set to Auto Disabled.
This setting allows the tuner to select which parameter is compared to the Auto Shift Point Table to determine when to automatically trigger a gear shift. 
Note that Engine RPM is not recommended on vehicles with a torque converter, as slip through the torque converter can be unpredictable in certain situations. 
Typical street cars use Driven Wheel Speed, Driveshaft Speed or Driveshaft RPM, depending on what's available on the car and tuner preferences. Driven Wheel Speed is most common. 
Circuit and rally race-cars with sequential transmissions often use Engine RPM to get optimal use of the rev range. 
Drag race cars can use different choices based off the style of transmission used and tuner preferences. 
Some tuners prefer to use Race Time to have the shift occur at a repeatable time since the car launched. 
Other tuners prefer to use Driveshaft RPM with Race Time used as the Shift Inhibit Variable to prevent shifts caused by wheel-spin. 
Driven Wheel Speed and Driveshaft Speed are less common, as drag tires don't have a consistent rolling radius, making speed measurements from axles inaccurate. 
If the car has a clutch rather than torque converter, Engine RPM can be used to optimise use of the rev range without having to convert to driveshaft speed per gear. Again, Race Time is commonly used as the Shift Inhibit Variable.

RPM Shift Point Enable 

Enables the RPM Shift Point Table. RPM-based shifting is similar to the Automatic Shifting, except that this shifting will occur even when the Gear Selector Position is in Manual, or there is no Gear Selector Position sensor. This allows the tuner to ensure that an up-shift happens just prior to hitting rev limit even if the drive doesn't request a shift. It also allows down-shifting if the engine RPM drops down so low that the car would be difficult to drive and/or when damage could occur (e.g. low RPM and high load). 
This functionality is more commonly used in vehicles which use a clutch, and less common in vehicles which use a torque converter. 
This functionality allows the transmission to automatically up-shift just as the engine reaches the ideal shift point for maximum power.

Block Down Shift Over-rev

When enabled, this functionality will block a down-shift request if that down-shift would cause the Engine RPM to be greater than the Main RPM Limit.  It is recommended to enable this setting. 
Requirements
This functionality requires the Vehicle Speed function to be enabled and configured, as well as having the sensors calibrated correctly. Note that the calibrate process may not work correctly if the ECU requires reboot and you don't reboot the ECU. 
The Gear Ratios function must also be enabled and calibrated. This calibration must happen after the Vehicle Speed sensor calibration. Note that the calibrate process may not work correctly if the ECU requires reboot and you don't reboot the ECU. 
Note that if you have a torque converter, you will have to lock it when performing this calibration.
One way to lock the torque converter is by enabling the Transmission Control Dyno Mode, setting the Dyno Mode Gear to the gear you wish to calibrate at the time, then accelerate until you reach the Dyno Mode Minimum Speed and click on the appropriate Gear Ratio Calibrate button. Note that since Dyno Mode isn't designed to change gears once it reaches it's target gear, in order to calibrate multiple gears, you will need to disable dyno mode, change gear, then re-enable it again. 
Behaviour
When a down-shift is requested (can be from paddle shift, auto shift, or even when entering Dyno Mode), the ECU looks at the current Vehicle Speed, calculates what the Engine RPM would be in the new gear, and compares that against the current Main RPM Limit.
If multiple shifts are requested (e.g. currently in 4th gear and 1st gear is requested), the request will be limited to the lowest gear which will be safe (e.g. allow the shift to 3rd because 3rd is safe, but 2nd is unsafe). 
Up-shifts are not checked because it is going to be better than staying in the current gear. 
Note that the behaviour of Block Down Shift Over-Rev is just one way to prevent shifts. Another feature, such as Shift Inhibit, can still prevent the shift even if this feature allows the shift. 
Pseudocode 
allow shift if ( (Vehicle Speed / X Gear Ratio ) * 1000 < Main RPM Limiter End RPM)
where X is the gear being requested
Example
Current Vehicle speed = 100 km/h.
Main RPM Limit is 6000 rpm.
Current gear is 4. 
A down-shift to 2nd is requested. 
First, the ECU calculates what engine RPM would be at this speed in 3rd gear. 
100 km/h / (20 km/h per 1000rpm) = 5,000 rpm.
This is below the Main RPM Limit of 6000rpm, so shifting down to 3rd is allowed. 
Next the ECU calculates what engine RPM would be at this speed in 2nd gear. 
100 km/h / (15 km/h per 1000rpm) = 6,666 rpm.
This is above the Main RPM Limit of 6000rpm, so the ECU is not allowed to shift to 2nd.
Because it is allowed to shift to 3rd but not 2nd, the ECU will begin a shift to 3rd gear, unless another feature (such as Shift Inhibit) prevents the down-shift. 


Shift Inhibit Variable 

Shift Inhibit is commonly used in drag racing to prevent shifts which would be caused by wheel-spin. 
It can optionally be used as a more customisable version of the Block Down Shift Over-rev on other vehicles, particularly those with paddle shift. 
Before the Transmission Control function initiates a gear shift (e.g. Down-shift from 2nd to 1st), it checks if that shift should be blocked by the Shift Inhibit.
e.g. if automatic shifting is based off driven wheel speed or driveshaft RPM, then the automatic shifting might determine that it's ready to shift. But if the driven wheels are only spinning that fast due to wheel-spin, then you might want to use Race Time as a shift inhibit to prevent the shift until the car is sufficiently far down the track. 

Recommended value: Disabled for most vehicles. 

Disabled - When this is selected, the Shift Inhibit functionality won't do anything. 
Engine RPM - Always available as a choice. 
Driven Wheel Speed - Requires the Vehicle Speed function to be enabled.
Requires the Drive Train sensor and/or one or more wheel speed sensors on a driven wheel to be enabled, wired in and calibrated.
Requires the Drive Type setting (In F4 setup page, Engine, Vehicle Information) to be set correctly. 
Driven Wheel Speed is calculated from the drive-train sensor and/or the wheel speed readings of the driven wheels, depending on which sensors are enabled. 
Commonly used for street, circuit and rally cars if they use a different Main Shift Point Variable. 
Drive-shaft Vehicle Speed - Requires the Vehicle Speed function to be enabled. 
Requires the Drive Train sensor to be enabled, wired in and calibrated. 
Similar to Driven Wheel Speed, but uses just the drive-train sensor. 
Drive-shaft RPM - Requires the Vehicle Speed function to be enabled. 
Requires the Drive Train sensor to be enabled, wired in and the number of teeth setting set appropriately. 
Similar to Drive-shaft Vehicle Speed, but more useful if the vehicle speed isn't calibrated properly, or is inaccurate. Is commonly used in drag racing, as the tyre circumference isn't constant. 
Race Time - Requires the Race Timer function to be enabled and configured appropriately to your application.
Commonly used in drag racing to prevent automatic shifts due to wheel spin. 

This allows the Transmission Control function to trigger torque reductions and/or throttle blips during gear shifts. 
Early electronically controlled transmissions (e.g. GM 4L60e, Toyota A340e) don't require this to be used, but there can be some benefits to using it with good configuration. Recommended: Torque Reduction after shift started. The Flat Shift Mode setting is typically set to Timed. 
Newer electronically controlled transmissions require engine torque to be manipulated during a gear shift. Torque reduction during up-shifts is very common, and is typically initiated after the shift actuator outputs. The Flat Shift Mode setting is typically set to Timed. 
Sequential dog-box transmissions typically use a percentage cut and/or ignition retard during up-shifts and a throttle blip during down-shifts. These are typically initiated before the shift actuator outputs. The Flat Shift Mode setting is typically set to Closed Loop if a Gear Position sensor is available, otherwise set to Timed. 

Allow Gear Skip

Some transmissions allow skipping over gears (e.g. going from 2nd to 4th without going to 3rd). Tick this box if you want the Transmission Control function to do this. 
Obviously sequential transmissions do not allow gear skipping.  If unsure, it's safer to leave this disabled. 

Post Shift Lock-out

After a gear shift has finished, further gear shifts are blocked for this amount of time. 
This allows shift solenoids and any shift mechanisms to return to their rest positions before being actuated again. 
If the Post Shift Lock-out is too short, the second requested shift may not happen, or may be incomplete, potentially damaging the transmission. 
Pneumatically actuated sequential transmissions require this to be sufficiently long (typical value 400ms). Most traditional automatic transmissions can have this set to 0 (assuming that the shift time table is set properly). 

Shift to First Enable

This functionality is optional. It is only needed in some circumstances. Most street, circuit and rally car configurations will leave it off.

Spool Up Gear Enable

Warning: This functionality should only be used if needed, and if the transmission is strong enough to handle the sudden shock load of shifting to 1st gear at full launch boost. 

This functionality is intended for drag race cars with automatic transmissions which do not have a Trans Brake available, and overpower the brakes when in 1st gear building boost on the start line. When the conditions are met, the Transmission Control function will put the transmission into the Spool-up Gear, enabling the turbo to spool up in a gear where the torque multiplication of the Torque Converter and Transmission are sufficiently low that the engine doesn't overpower the brakes. When the conditions are no longer met, the Transmission Control function will attempt to shift directly to 1st gear. 

Dyno Mode

Dyno Mode Enable

Whether or not the Dyno Mode is enabled. Note that it goes yellow as a reminder to disable it when finished. 

Dyno Mode Minimum Speed

If Dyno Mode is enabled, when the driven wheel speed exceeds the Dyno Mode Minimum Speed, the Transmission Control function will enter Dyno Mode.  It will remain in Dyno Mode even if you drop below this speed again. This is deliberate to allow the tuner to reach all RPM sites they wish to tune. 

Dyno Mode Gear

What gear to shift to when Dyno Mode is enabled and the Dyno Mode Minimum Speed is met.
This follows the normal gear shift rules such as:
Only shifting one gear at a time unless Allow Gear Skip is enabled.
Not shifting if the Shift Inhibits won't allow the shift. 
Not shifting if Block Down Shift Over-Rev is enabled and a down-shift is requested which would cause the Engine RPM to exceed the Main RPM Limiter End RPM. 
Waits for the post-shift lock-out between shifts.
Shift Duration table acts as normal if available. 
Flat shift link occurs as normal. 

Torque Converter Lock In Dyno Mode 

‚ÄčIn the Torque Converter settings, there's a tick-box setting to lock in dyno mode. It is recommended to enable this feature, in order to allow the engine to reach high load, low RPM sites. 
This setting greys out and is unavailable if Torque Converter function is disabled or Lock Option is Disable.



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