REV2 Board: Secondary Port Fuel Injection - bootmod3 CustomROM V2

Overview

CustomROM V2 provides secondary port fuel injection integration with the REV2 Board through FlexRay and DirectPWM. To configure which mechanism the DME uses to send injector duty cycle to the REV2 board refer to the REV2 Board: Install and Map Configuration.

Screenshot below shows the tables available in the bootmod3 Map Editor for configuration of the secondary fuel injectors as well as a choice among 4 control strategies for port fuel injection, blend factor tables for flex fuel based blending between Gasoline (Base) and FlexFuel table pairs, similar to how we’ve implemented Ignition Timing, Lambda Target blending and others on CustomROM V1.

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Fuel Pressure Sensor Setup

Refer to this section on how to set up your Fuel Pressure sensor which is required for correct secondary port fuel injector operation: REV2 Board: Fuel Pressure Sensor Setup and Calibration - CustomROM V2

Secondary Fuel Pump Setup and MAP vs. Engine Speed Duty Cycle Control in Map Editor

Refer to this section on how to set up control of the auxiliary fuel pump for your secondary port injection side:

REV2 Board: Secondary Fuel Pump Wiring and Calibration in Map Editor (Port Injection) - bootmod3 CustomROM V2

Secondary Port Fuel Injector Calibration

Fuel Injector Characterization

Look up the calibration specifications for the secondary fuel injectors used on the vehicle and enter them into the Fuel Injector Characterization table with Differential Fuel Pressure vs Battery Voltage axis and values being injector dead/offset times as provided by the manufacturer.

Example shown below is for Injector Dynamics ID2600-XDS injectors as provided by the manufacturer here https://injectordynamics.com/injectors/id2600-xds/.

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Fuel Injector Flow Curve / Slope

Look up the calibration specifications for the secondary fuel injectors used on the vehicle and enter them into the Fuel Injector Flow Curve / Slope table with Differential Fuel Pressure as the axis and values being injector flow values in cc/min for the given Differential Fuel Pressure (PSI) as provided by the manufacturer.

Example shown below is for Injector Dynamics ID2600-XDS injectors as provided by the manufacturer here https://injectordynamics.com/injectors/id2600-xds/.

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Secondary Port Injection Control Strategy

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CustomROM V2 provides a choice among 4 port injection control strategies as shown in the table description above, recommended (default) being the Strategy 3:

• (Basic Strategies) Injector Duty Cycle Based Port Injection Strategies:

  • Strategy value 0 → Load vs. Engine RPM vs Injector Duty Cycle

  • Strategy value 1 → Manifold Absolute Pressure (MAP) vs. Engine RPM vs Injector Duty Cycle

• (Advanced Strategies with DME Fuel Mass Calculation) PI DI % Split Based Port Injection Strategies

  • Strategy value 2 → Load vs. RPM vs PI DI Split

  • Strategy value 3 → Manifold Absolute Pressure (MAP) vs. Engine RPM vs PI DI Split (Recommended)

Each of the strategies above provides for a base (Gasoline) table for a given strategy as well as a FlexFuel version of the table that DME blends between Gasoline and 100% Ethanol based on the values in the Blend Factor tables, either the Blend Factor (PI IDC) or the Blend Factor (PI DI Split) depending on strategy selected.

(Basic) Load vs Engine RPM vs Injector Duty Cycle - Base (Gasoline) and FlexFuel (100% Ethanol) - Port Injection Control Strategy 0

Name of these tables is self explanatory in terms of the axis. The values in the table provide for sort of a basic port injection tuning approach as tuner would be setting an injector duty cycle (IDC%) value in each cell. While not recommended, we provide it in CustomROM for tuners that wish to use this approach to tune their port injection. We strongly recommend using Strategy 3 described further below for its advanced approach to injecting fuel based on calculated fuel mass.

PI IDC Target is the table which is the only one used for port injection fueling if FlexFuel is disabled on a given map slot for Strategy 0.

If FlexFuel is enabled on a given map slot through CustomROM → Activation switches, then the PI IDC Target table becomes the Gasoline (0% ethanol) calibration table and the PI IDC Flex Fuel Target table represents values for 100% Ethanol.

Example of the Blend Factor (PI IDC) table is below:

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Axis is ethanol content % and values determine the blend factor between the base table and the flex fuel table where a value of 0 represents base table being used fully without blending, value of 0.5 represents a blend half way between values in the blend and flex fuel table, and 1.0 represents a full transition to the IDC values in the Flex Fuel table. For further explanation on blend factor logic refer to CustomROM V1 documentation.

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(Basic) Manifold Absolute Pressure (MAP) vs Engine RPM vs Injector Duty Cycle - Base (Gasoline) and FlexFuel (100% Ethanol) - Port Injection Control Strategy 1

Same idea here as Strategy 0 above except this provides for Manifold Absolute Pressure (MAP) vs Engine RPM axis along with Flex Fuel blending as described above.

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(Advanced) Load vs Engine RPM vs PI DI Split % - Base (Gasoline) and FlexFuel (100% Ethanol) - Port Injection Control Strategy 2

As with Strategy 0, Strategy 2 has Load and Engine RPM as the axis but the values represent a split to the total DME calculated target fuel mass.

For example, a value of 20% in this table indicates that the DME should inject 20% of the total DME calculated fuel mass through port injection for a given Load vs. Engine RPM area.

Tuning with the Load variable on the axis, while being an OEM sort of approach, has its limitations and drawbacks when it comes to complexity of the Load calculation/model which can change quite drastically at very high boost levels and different ambients.

Since DME already calculates the required target fuel mass, using the PI DI Split table is far easier with MAP vs. Engine RPM as the axis which is exactly what Strategy 3 explained below does and is the one we recommend using instead of Load vs Engine RPM. For anyone that prefers tuning with this strategy, although we advise going with strat = 3, we’ve left the logic and tables in place so that can also be done.

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PI DI Split is the table which is the only one used for port injection fueling if FlexFuel is disabled on a given map slot for Strategy 2.

If FlexFuel is enabled on a given map slot through CustomROM → Activation switches, then the PI DI Split table becomes the Gasoline (0% ethanol) calibration table and the PI DI Split Flex Fuel table represents values for 100% Ethanol.

Example of the Blend Factor (PI Split) table is below:

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Axis is ethanol content % and values determine the blend factor between the base table and the flex fuel table where a value of 0 represents base PI DI Split table being used fully without blending, value of 0.5 represents a blend half way between values in the blend and flex fuel table, and 1.0 represents a full transition to the PI DI Split values in the Flex Fuel table. For further explanation on blend factor logic refer to CustomROM V1 documentation.

(Advanced) MAP vs Engine RPM vs PI DI Split % - Base (Gasoline) and FlexFuel (100% Ethanol) - Port Injection Control Strategy 3 (DEFAULT / RECOMMENDED)

As with Strategy 1, Strategy 3 has Manifold Absolute Pressure (MAP) and Engine RPM as the axis but the values represent a split to the DME calculated target fuel mass.

Tuning with the MAP variable on the axis, makes things much simpler to tune with than dealing with Load. Port injection should be tuned with the manifold pressure reference. OEM MAP sensor is only a 2.5bar and requires an upgrade as described in the following section: Boost Sensors: MAP (Pre-Throttle) and Intake Manifold (TMAP) Pressure Sensor Upgrade, Calibration - CustomROM V2

Since DME already calculates the required target fuel mass, using the PI DI Split table is far easier with MAP vs. Engine RPM as the axis which is exactly what this strategy does and is the one we recommend using.

For example, a value of 20% in this table indicates that the DME should inject 20% of the total DME calculated fuel mass through port injection for a given MAP vs. Engine RPM area.

Since the DME fuel mass target calculation can max out at a certain value depending on where the car is pushed, the % values in the PI DI Split table can go past 100%. Max value, at this time, for the PI DI Split table is 400% giving it the ability to fuel up 4x the calculated DI fuel mass value without issues.

Here’s an example of a PI DI Split table MAP vs Engine RPM for a setup that ran on a 3.35L S58, running a Fuel Pressure Regulated return style fuel system with ID2600-XDS injectors and a Precision 8085 NextGen Turbo to around 45-50psi of boost.

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