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Navigation: MTune Settings > Fuel

Staged injection

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Note: Incorrect settings of the injection staging system can cause the engine to run lean.

Double-check all settings and test the engine under controlled conditions.

Peak-Hold injectors can only be used as secondary's on MaxxECU REV7 units and above.



General for staged injection

The secondary injectors are set as "Secondary injector".

Injection pattern is the same as the primary injectors.

"Secondary injector 1" opens with INJ 1 and so on.

Depending on number of injector outputs on your MaxxECU, injectors might be connected in parallel.



Staging mode: Auto transition

When the primary injectors are maxed out, MaxxECU opens the secondary injectors.

The primary injectors will continue to inject fuel together with secondary injectors.

Tuned as usual, the transition is handled automatically by the MaxxECU.


Staging mode: Manual control of secondary injectors (extra fuel table 1)

The amount of injected fuel is controlled by "extra table 1" (select secondary fuel amount for this table).

The injected fuel on the secondary injectors is only controlled by this table. All enrichment are added to the primary injectors only.

This mode is suitable for adding additional fuel when the primary injector capacity is to low, or when injecting an ADDITIONAL fuel/coolant to an engine (such as water/methanol).


Note: Not suitable for dual fuel setups, as some fuel is still added by the primary injectors.


Staging mode: Primary/secondary injector changeover (extra fuel table 1)

"Extra table 1" controls the distribution of fuel between the primary and secondary injectors. The amount of fuel is controlled by the VE-table.

0% means all fuel will be added by the primary injectors, 100% will add all fuel with the secondary injectors.

This can be used for trumpet mounted secondary injectors, or dual fuel/fuelsystem setups. Secondary injector fuel and injector size can be different than the primary, the ECU will calculate the correct fuel amount automatically.


Note: It is very important that the opening time and the flow is correct to give a linear transition.



Secondary injectors fuel stoich AFR

Specifies fuel type used on engine.




Specifies installed injector type.


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


Injector flow

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


Fuel pressure

Specifies base fuel pressure. Used to adjust pre-defined injector flow based on a theoretical curve.

3 bar is a recommended value to use since this is default for most injectors when flow tested from manufacturer.


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.


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.


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.



Video example

MaxxECU Academy - Staged injection