Injector Timing Settings

Note: Refer HERE for an explanation of Injector Timing.

The following settings allow the Injector Timing to be tailored to the application.

INJ Timing Mode

This setting has the following options:

·	Single Zone - In most cases it will be sufficient to use fixed injector timing. In these cases use the Single Zone option.

·	Table - In some applications it may be desirable to change the injector timing with engine speed or load. In these cases use the Table option.

INJ Timing Position

This setting specifies what the Injector Timing number(s) represent. Options are:

·	End of Injection - The injector timing value represents the engine position where the injector pulse ends. Because the injector closing time is specified, the ECU calculates the injector opening time required to inject the required amount of fuel. This mode is the most commonly used option.

·	Center of Injection - The injector timing value represents the engine position at the centre of the injector pulse. The injector opening and closing time is adjusted so that the required amount of fuel is injected.

·	Start of Injection - The injector timing value represents the engine position where the injector pulse starts. Because the injector opening time is specified, the ECU calculates the injector closing time required to inject the required amount of fuel.

On Rotary engines only the Start of Injection option can be used.

Injector Timing

This setting is only available when INJ Timing Mode is set to Single Zone. Injector Timing specifies the injector timing to be used throughout the entire operating range. The units are degrees before top dead centre (BTDC) with reference to top dead centre between the compression and power stroke. Therefore 360 represents TDC between the exhaust and inlet stroke.

Injector Timing Table

This setting is only available when INJ Timing Mode is set to Table. The Injector Timing Table allows the injector timing to be altered with engine speed and load. The units are degrees before top dead centre (BTDC) with reference to top dead centre between the compression and power stroke. Therefore 360 represents TDC between the exhaust and inlet stroke.

Injection Timing Split

This function allows every second cylinder in the Firing Order to have its injection timing trimmed. This is designed to help prevent "charge robbing" that occurs on some Siamese port and irregular timed engines. This function only applies to Sequential and Sequential Staged Injection Modes.

Warning: This is an advanced feature that should only be enabled by advanced tuners. A means of measuring individual cylinder efficiency (eg a pyro per cylinder) must be used when adjusting injector timing split numbers.

The following options are available:

·	OFF - The injection timing split function is disabled.

·	ON - Injection timing split will be applied to every second cylinder in the firing order according to the trim number in the Injector Timing Split Table.

Injection Timing Split Table

This table is only available when Injection Timing Split is set to ON. The numbers entered in the Injection Timing Split Table are added to the normal injection timing number achieved using the Injection Timing function but only for every second cylinder in the Firing Order. The range of table numbers is -360 to 360 degrees. Units are crankshaft degrees. Note that if this table has all zero in it then all cylinders have the same injection timing.

Every second cylinder in the Firing Order will have its injection timing altered by the number in the table. For example:

·	Firing order 1-2 - Cylinder 2 injection timing will be trimmed.

·	Firing order 1-3-4-2 - Cylinders 3 and 2 will have their injection timing trimmed.

·	Firing order 1-2-7-8-4-5-6-3 - Cylinders 2,8,5 and 3 will have their injection timing trimmed.

Injection Timing Split Table Application Examples

For a four cylinder engine with Firing Order 1-3-4-2:

·	If the injection timing (from single zone or the injector timing table) is 400 degrees BTDC, the injector will normally be fired at 400 degrees BTDC for each cylinder.

·	If an injection timing split of -50 then split timing is 400 + -50 = 350 deg BTDC, so:

·	Cylinders 1 and 4 will have their injectors fired at 400 deg BTDC

·	Cylinders 3 and 2 will have their injectors fired at 350 deg BTDC

For a V-Twin engine with TDC points at 0 and 315 degrees:

·	To set end of injection to just before the intake valve closes, normal injection timing must be around 200 deg BTDC (refer to diagram here).

·	If an injection split of 180 degrees is used, then split timing is 200 + 180 = 380 degrees, so:

·	Cylinder 1 will have its injection end at 200 deg before its TDC compression (actual -200 degrees relative to TDC no 1).

·	Cylinder 2 will have its injection end at 380 deg before its TDC compression (actual -65 degrees relative to TDC no 1). This is just before the intake valve opens.

Note: It does not matter if the engine has regular firing intervals or irregular (odd fire). Calculation is performed relative to the TDC point for each cylinder.

It is recommended to draw out a valve diagram for each cylinder similar to the diagram HERE to help visualise the effect of injector timing and injector timing split changes.