Transient Fuel

Tuning transient functions in Emtune is done through a combination of function setup and table settings.

The following runtimes are generated which are applied/added/subtracted to final injection PW.

Accel Fuel – Added fuel PW (added to final injection PW)
Accel Clamp – The maximum PW that can be added at that moment
Decel Fuel – Decreased fuel PW (subtracted from final injection PW)
Decel Clamp – The maximum PW that can be decreased at that moment
Fuel Acce/Decel Scaler – The amount of PW governed by Engine Temperature Comp multiplier

Transient Setup

Accel Enable: Enable or Disable Transient Acceleration fuel mode,

Decel Enable: Enable or Disable Transient Deceleration fuel mode,

Accel/Decel Mode: Configures runtime input for transient function initiation.

0: TPS 1 - Throttle position sensor 1 or Drive By Wire Servo Position Sensor 1

1: MAP - Manifold Absolute Pressure Sensor

2: PP 1 - Pedal Position Sensor 1

Accel/Decel Threshold (+/-): The rate of change threshold or lockout of the Accel/Decel mode runtime.

This value is set as a percentage of change over a second over it’s previous state.

Lower numbers increase the sensitivity in initiating the transient fuel function.

A typical value is 1.0 %/sec.

The Accel Sensitivity Table is the multiplication factor as a percentage of fuel added, based on the rate of change of the Accel/Decel mode

Note: Must be set to PP or TP

Example:

dTP1 = 20%/sec

Accel Sense = 10%

Fuel base pulse width = 5.0ms

Accel PW = 20 * 0.10 = 2.0ms

Total fuel pulse width = 5.0ms + 2.0ms = 7ms

The Accel Clamp Table limits the maximum amount of increased PW (percentage vs calculated PW) allowed.

Example:

Accel Clamp = 50%

Fuel base pulse width = 4.0ms

Max Accel Fuel PW allowed = 2.0ms

Total fuel pulse width = 6.0ms

The Accel Engine Temperature Compensation Table introduces a multiplier of the calculated accel fuel value against engine temperature

Example:

Accel fuel = 10ms

Engine Temp Comp = 1.5

Total Accel fuel = 10 * 1.5 = 15.0ms

The Accel Decay Table controls the rate of decay or how quickly the added accel fuel is removed as a percentage of an engine cycle.

Example:

Accel decay = 10

Accel fuel will decay back 10% every cycle