Fuel System

Fuel System


‚ÄčFuel System

This page is used to configure the Fuel Injection System.

Injection System

Disable Injectors

Enabling this will disable all injector outputs. (Default = Disabled)

Enable Short Pulse Width Adder

Enabling this will add a Short Pulse Width Adder table per injection stage. This adder is used to increase or decrease the actual pulsewidth at the injector when the injector is operating in its non-linear fuel delivery range. For more information see Fuel Tuning > Stage > Short Pulse Width Adder.

Injector Timing Method

Selects the timing of the injection pulse in relation to TDC. Either timed to the start of the injection pulse, or timed to the end of the injection pulse. Default = End of Injection.

Number of Stages

The number of separate fuel injector stages that are to be used. The maximum number of stages depends on the ECU capabilities.

Staging Method (Elite series ECUs only)

Selects the staging method used for multi-stage fuel injection when using Elite series ECUs. When using a Nexus series ECU, the staging method is always 'Nexus Style' and cannot be changed. It is recommended to always use 'Nexus Style' when tuning an engine from scratch. See below for staging information.

Stage Flow Percentage Tables

Only available when Staging Method is Nexus Style, or you are using a Nexus series ECU. Enables the per stage flow percentage tables which allows greater control over the fuel delivery from each injection stage. For more information see below, and Fuel Tuning > Stage > Flow Percentage.

Staging Set Up

Stages

Configuration for each of the enabled stages.

# Of Injector Outputs

The number of physical injector outputs used for each stage.

Injection Mode

The injection delivery method for each stage. (Default = Sequential)

Sequential

Each injector output fires once per engine cycle in sequence and typically one output per cylinder. This setting requires a Trigger Type that supports full engine cycle synchronisation, typically with a crank and a cam position sensor. Injection is timed with 720 degree crank position.

Semi-Sequential

Injectors are fired in groups. This setting requires a Trigger Type that supports crank-only position (eg. missing tooth triggers with no cam position sensor). Injection is timed with 360 degree crank position.

Multi-Point

All injector outputs are fired together. This setting only requires a Trigger Type with one trigger per spark event. Enabling this setting in turn enables the Injections Per Cycle setting.

Batch

Injector outputs are divided into two groups which are fired alternately. This setting only requires a Trigger Type with one trigger per spark event. Enabling this setting in turn enables the Injections Per Cycle setting.

Injector Configuration

Configures how the fuel is distributed in the intake. (Default = Per Cylinder)

Per Cylinder

Each injector output supplies fuel to one cylinder. Eg. the injectors are in each runner for one cylinder and cannot supply fuel to another cylinder. This allows per-cylinder corrections for fuel.

Shared All Cylinders

Each injector output supplies fuel to all cylinders. Eg. Injectors are in a common plenum or pipe that supplies air to all cylinders.

Shared Opposing Cylinders

Each injector output supplies fuel to 2 cylinders. Eg. when a 6-cylinder engine with firing order 1-5-3-6-2-4 with Semi-Sequential as the Injection Mode may have only 3 injector outputs enabled. With cylinder 1 and 6 sharing one output, 5 and 2 sharing another output, and 3 and 4 sharing the last output. Opposing cylinder are shared in this case.
Injections Per Cycle
The number of injections per injector output for the full engine cycle. 720 degrees for 4 stroke engines in Full Sync, or 360 degrees for 2 stroke and Rotary engines. (Default = 1)

Staging Method Information

This staging method is recommended for all new installations and is the only option for Nexus series ECUs. When selected, each stage will have a 'Staging Duty Cycle' parameter. This method also allows 'Stage Flow Percentage' control which is explained below. 

With Nexus staging, each injection stage will operate up until it reaches its 'Staging Duty Cycle', at which point that stage will hold its duty cycle and the next injection stage will start to deliver fuel. This repeats for each injection stage that reaches its 'Staging Duty Cycle'. Once all injection stages have reached their 'Staging Duty Cycle', all stages will increase their duty cycle to 100% together. The rate of increase of each stage is controlled so all stages reach 100% duty cycle at the same time.

Example: 2 stages of injection with Stage 1 Staging Duty Cycle set to 50%, and Stage 2 Staging Duty Cycle set to 50%. 


Example: 2 stages of injection with Stage 1 Staging Duty Cycle set to 50%, and Stage 2 Staging Duty Cycle set to 75%. 


Example: 3 stages of injection with Stage 1 Staging Duty Cycle set to 50%, Stage 2 Staging Duty Cycle set to 50% and Stage 3 Staging Duty Cycle set to 50%.


Example: 3 stages of injection with Stage 1 Staging Duty Cycle set to 40%, Stage 2 Staging Duty Cycle set to 60% and Stage 3 Staging Duty Cycle set to 80%.

Stage Flow Percentage 

NOTE: Incorrect tuning of the Flow Percentage tables can cause undesired fuel distribution across stages. Please fully understand how the Flow Percentage tables work before attempting to use them. When setting Flow Percentage table axis, avoid using any channels that reference (or are affected by) another stages duty cycle.

When enabled, allows for greater control over the proportion of fuel delivered by each injection stage. The Flow Percentage tables control how much of the engines total fuel requirement is delivered by each injection stage, up to the Staging Duty Cycle. Once a stage has reached its Staging Duty Cycle, excess fuel is distributed to lower stages. Stage 1 does not have a Flow Percentage table, as it will always deliver the remaining fuel requirement if needed.

Example: Stage 1 Staging Duty Cycle is set to 50%. Stage 2 Staging Duty Cycle is set to 50%.


In the above scenario, the ECU is delivering all fuel via Stage 1, as the Stage 2 Flow Percentage is 0%, and Stage 1 has not yet reached its Staging Duty Cycle.




In the above scenario, Stage 1 has reached its Staging Duty Cycle, and Stage 2 is now delivering the additional fuel requirement. Note the output of the Flow Percentage table is still 0%.




In the above scenario, the Stage 2 Flow Percentage is requesting 25% of the total fuel requirement be delivered to the engine via Stage 2. This reduces the duty cycle of Stage 1.



In the above scenario, the Stage 2 Flow Percentage is now requesting 50% of the total fuel requirement be delivered to the engine via Stage 2. This has further reduced the duty cycle of Stage 1.


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