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Navigation: MTune Settings > Fuel

Fuel inj general

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General fuel injection settings

 

Injection method

Specifies injection mode.

Sequential is always preferable, but requires a fitted cam trigger sensor.

Simultaneous - All injectors are opened at the same time once every 720 degree.

Group - Injectors are opened every 360degrees, but only half of them.

Sequential 360 (4-stroke) - Injectors are opened individually on each cylinder every 360 degrees. 50% fuel load each injection event.

Sequential 360 (2-stroke/wankel) - Injectors are opened individually on each cylinder every 180 degrees. Full fuel load each injection event.

Sequential 720 - Injectors are opened individually on each cylinder once per engine revolution. If injection/ignition is in the wrong engine cycle, change Cam signal position in Inputs --> Trigger, Trigger decoder.

Sequential 720 without sYNC - Injects fuel every 2 crankshaft revolutions. Used with trigger systems without cam sync. As the ECU doesn't know if the cylinder is in the intake or exhaust cycle the fuel may be injected during either one. This is determined each time the engine is started, and will always be the same when engine is running.

Manual injection distribution (advanced) - See manual injection distribution, output entry method below.

 

Fuel stoich AFR

Specifies fuel type used on engine.

Note: Can be set to Custom setting, see example below.

 

Multiply lambda

Specifies if VE should be calculated by using the  Lambda target table.

Note: For MaxxECU to present "real" VE values, this must be checked.

 

Use MAP-sensor

Specifies if MAP sensor should be used for fuel calculations. <-- recommended.

Disable where TPS is selected as main load axis and MAP readings are unstable because of wild cams and/or intakes.

Note: Regardless of your axis source, values in ex the main VE table, the MAP-sensor data is used in the VE calculations when use map-sensor = enabled.

 

Staged injection

Enable/disable the use of Staged injection functionality.

 

 

Injector settings

 

Injector

Specifies installed injector type.

Note: If your injector is missing, please use "User defined" and enter correct values.

 

Peak-Hold drivers

Peak and Hold drivers MUST be enabled for low impedance(below 8 ohms) injectors, and disabled with high impedance injectors (saturated).

 

Peak current

Specifies "peak" current which opens the injector.

3000mA = 3A which is default and used by most injectors.

Current above 5A per output is only allowed with 2 injectors per output.

Note: MaxxECU rev6+ and higher supports higher peak current, up to 8A.

 

Hold current

Specifies hold-current for injector.

1000mA = 1A works for most injectors.

 

Injectors per output

Adjusts the injector drivers for the load.

MaxxECU PRO, RACE and V1 (rev7+) can use max 2 Peak-and-Hold injectors per output.

All MaxxECUs can use max 3 high resistance injectors per output.

 

Injectors per cylinder

Adjusts the fuel calculations to account for the fuel flow per cylinder.

 

 

Injector flow settings

 

injector flow tracking

Note: Only visible when injector is set to user defined.

Fixed flow with default pressure compensation - The ECU uses a built-in fuel pressure correction for the entered injector flow. The 100% values are at 3 bars, if the fuel pressure is lower, the injector flow is increased (pulse widths are decreased as a correction) as an example.

flow/pressure list - The ECU does NOT use any built-in pressure correction. All pressure vs. flow is done via the data entered in the Injector flow table that shows up. This is what you would use if you have data for the flow rates at different pressures. The ECU always uses the RT-value Primary(or secondary) fuel pressure  as a source for the pressure correction. How this value is calculated depends on the Fuel pressure tracking setting below.

 

Injector flow

Note: Only visible when injector is set to user defined.

Specifies injector flow in cc/min at 3bar fuel pressure.

 

Fuel pressure tracking

Fixed value - The fuel pressure follows the MAP at a 1:1 ratio. The ECU assumes that pressure across the injector is always that's entered in the Fuel pressure setting.

Fixed value, fixed pressure - The fuel pressure does NOT track the MAP. The ECU assumes the fuel pressure to be Entered-Fuel-Pressure-MAP+BARO. So at vacuum when the differential fuel pressure is higher than at load the ECU assumes the fuel pressure is higher, calculates a higher flow rate, and decreases the injector pulse widths.

fuel pressure sensor 1/2 tracking - The ECU uses the actual sensor value to correct the flow. The sensor is setup as class=Fuel pressure sensor X in kPa. The tracking type offset and target pressures are setup under the Fuel pressure sensor X page.

Note: You want the "Primary fuel pressure" RT-value to read 0kpa with no pressure, and 300kpa at 3bars positive fuel pressure etc.

Note: Fuel pressure deviation tracking (without fueling correction) can be done without this enabled here.

 

Fuel pressure

The specified fuel pressure when the above fuel pressure tracking is set to fixed value.

Note: Not used when fuel pressure sensor 1/2 tracking above is active.

 

 

Injector dead time settings

 

Dead time entry method

Specifies the dead time entry method, List for simple mode and Table for the advanced users.

list (voltage dependant) - Simple mode using a list with the battery voltage as axis.

table (voltage + fuel pressure dependant) - Uses a table for the dead times.

 

Injector dead time

Injector dead time at different voltages. "Dead time" is the amount of time it takes for the injector to transition from closed to open.

 

Pulsewidth adder

Injectors become Non-Linear at very low pulsewidth. This table allows you to compensate for this. These values can be supplied by the injector manufacturer.

 

 

Injection even angle

 

angle reference

The injection angle can refer to degrees before TDC of the ignition phase or degrees after TDC  of the ignition phase.

 

event edge

The point on the injection event the injection angle refers to.

 

Injection angle table

Specifies the injection angle for each cylinder. Affects mostly idle and the low RPM band.

 

 

 

Examples

 

Custom fuel stoich AFR

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You can even create your own custom stoichiometric ratio based on any X or Y axis, in the above example we have configured a switch wired to the digital input 1, which can be used to switch between petrol or E85 VE calculations.