Honduino OBD1 DPFI - V1

Before connecting the ECU to the car

Before installing the ECU into the vehicle, some pre-installation configuration must be performed.

Update the firmware (optional)

1. Download and install STM32CubeProgrammer V2.14

2. Download the latest FIRMWARE

3. Click on the BOOT button on the board and plug the USB cable into the computer

   

4. In STM32CubeProgrammer, select USB, refresh the devices, select the ECU, and connect.

   

5. Go to the “Erasing & Programming” menu, browse, and select the firmware.

   

6. Insert the start address: 0x0800000

7. Select the boxes: “Run after programming”, “Full chip erase”, and “Download file”

8. Click “Start Programming”

9. You successfully updated the firmware! Now, close all STM32CubeProgrammer windows and restart the ECU by clicking the RESET button or unplugging and plugging the USB cable.

Connecting to the software

1. Download and install: TunerStudio

2. Plug the USB; it will automatically open a virtual drive with a file. Extract it and save it on your desktop.

   

3. Open TunerStudio, create a new project, click “Other / Browse”, and select the firmware.ini file extracted earlier.

   

4. Use RS232 Serial for USB connection or Bluetooth direct.

   

Base settings

Configure the number of cylinders, engine displacement in liters, firing order, and fuel strategy.

Ignition (Distributor / COP)

WARNING: Use only smart coils or dumb coils with external igniters.

1. The ICM switch needs to be adjusted based on the ignition setup. (CRITICAL)

   

2. Configure the Spark Mode and Output Mode. (CRITICAL)

   WARNING: If the output mode isn’t configured correctly, the coil(s) will overheat and potentially get damaged. If the ignition is ON and the coil starts to heat up, the configuration is likely incorrect.

   
   

   Spark mode:

   • Single coil: Distributor
   • Individual coils: Smart coils in sequential mode

   Ignition output mode:

   • Honda distributor DPFI coil: Default (Going Low)
   • Most smart coils: Default (Going Low)

3. Ignition voltage output: Select the voltage for each pair of ignition output via the jumpers:

   H1 + H2 H3 + H4 H5 + H6 H7 + H8 H9 + H10 H11 + H12

   

   • Honda distributor: 12V
   • Most smart coils: 5V

4. If using individual coils: Connect each coil signal wire to the OBD1 C connector.

   

   • C5: Coil 1 (High side 1)
   • C7: Coil 2 (High side 2)
   • C9: Coil 3 (High side 3)
   • C11: Coil 4 (High side 4)

WARNING: Be sure to read all sections on ignition to avoid damaging any coils.

Injection

WARNING: Use only high-impedance injectors (> 8 ohms) or low-impedance injectors with a resistor box.

1. Configure the outputs that correspond to each cylinder.

   
   

2. Injector base settings:

   • Injection mode
   • Injector flow
   • Compensation mode
   • Dead time

   
   

Temperature sensors

Coolant temperature sensor

Intake temperature sensor

Trigger wheel

1. Configure the trigger wheel according to your distributor disc:

   

   Stock trigger disc:

   

   24-1 trigger disc:

   

Connect the ECU to the car

Throttle Position Sensor

Adjust the Primary minimum (ADC) and Primary max (ADC) until the TPS reads 0% without pressing the throttle and 100% at full throttle.

MAP sensor

Any MAP sensor can be used, but the most common is the stock one on input A4.

You can also solder an onboard MAP sensor to A5 or connect to the onboard auxiliary inputs.

Radiator fan

A valve controls the radiator fan mechanically, but the ECU can activate the relay independently using an unused Low side output.

Ignition base timing (same as the rotation of the distributor)

To sync the ignition timing with the engine, adjust with the help of a Timing Light gun.

1. Disable the injection (if the car starts, skip this step)

   
   

2. Change the timing mode from dynamic to fixed, so the ECU fires the coil always at the 0-degree angle.

   
   

3. Use a white sharpie to mark the 0-degree mark on the crank pulley.

   The crank pulley has four marks, with the lone mark of the four being 0 degrees (TDC).

   

4. Attach the timing light clamp to spark plug wire 1, ensuring the arrow points toward the spark plug.

5. Adjust the Trigger Angle Advance value until the 0-degree mark on the crank pulley aligns with the pointer on the distributor cover.

   
   

6. Unlock the timing so the ECU sends the ignition table values.

   
   

7. The timing is synced, now start your car 🥳🥳🥳

Idle control

1. Adjust the idle when the engine is at its normal operating temperature.

   
   

2. Idle Target RPM is used to control the idle in closed-loop mode.

   
   

3. Warmup Idle Multiplier adjusts the value based on the open-loop idle setting.

   
   

4. Closed-loop idle adjusts the idle using a PID algorithm.

   
   
   

5. Closed-loop idle timing adjusts the idle by advancing or retarding the ignition timing.

   
   

VTEC solenoid

This engine doesn’t have a VTEC solenoid, but you can upgrade to a head with VTEC.

• 0 = OFF
• 100 = ON

Vehicle Speed Sensor

Air Conditioner

Extra features

Wideband

To tune the VE table, a wideband sensor is necessary for measuring the air-fuel ratio.

1. You can either connect an LSU 4.9 sensor directly to the onboard controller or use a 0-5V signal from an external controller via an auxiliary analog input.

   

   OBD1 C connector	LSU 4.9 sensor
   C2	5 (IA)
   C4	6 (NERMEST)
   C6	1 (IP)
   C8	2 (VGND)
   C10	3 (HEATER-)
   C12	4 (HEATER+)

   

2. Configure the wideband linear output values.

   
   

Launch control

The launch control is used to launch… I mean, spit flames, a lot of 🔥🔥🔥!

1. Select the activation mode: it can be Speed-based, Launch, Clutch, or Brake button.

   If you choose to use a button, some cars have clutch switches, but most will need to be wired to a switch that sends a ground signal to pin OBD1 B7 (Aux Digital Input D2) when the clutch is pressed.

   
   

   • Launch RPM: A secondary rev limit engaged by the driver to help launch the vehicle faster.
   • Ignition Retard Adder: Range from Launch RPM for Timing Retard to activate.
   • Hard Cut RPM Adder: Range from Launch RPM to activate Hard Cut.
   • Smooth Retard Mode: Interpolates the Ignition Retard from 0 to 100% within the RPM range.

Anti-lag

The ANTI-LAG is used to help decrease the lag of the… I mean, spit flames, a lot of 🔥🔥🔥!

1. Wire a switch that sends a ground signal to an unused auxiliary digital input.

   
   

Boost control

A boost controller is a device used to increase the boost pressure produced by the turbocharger.

1. Connect the negative wire of the boost controller valve to an auxiliary low-side output.

2. Activate a boost limit to protect the engine from overboost.

   
   

   • Boost cut pressure (absolute): MAP value above which fuel is cut in case of overboost.
   • Boost cut pressure hysteresis: If hard cut is 160kPa, and boostCutPressureHyst is 10, when the ECU sees 160kPa, fuel/ignition will cut and stay cut until 150kPa (160-10) is reached.
   • 160kPa absolute = 100 kPa atmosphere + 60 kPa of boost

3. Select Open-loop mode and the auxiliary output.

   Open-loop: Regulates the boost valve’s duty cycle according to the percentage values in the control table.

   
   

4. Configure the Boost control open-loop table.

   
   

5. It’s possible to enable Open + Closed-loop and control the boost more precisely.

   Open + Closed-loop: Regulates the boost valve’s duty cycle using the open-loop table, combined with a PID algorithm and a target table.

   
   
   

CEL: Shift / Warning light

The engine light can be used as a programmable output. I prefer to use it as a shift indicator and for coolant temperature warnings.

• 0 = OFF
• 100 = ON

Tachometer

The stock distributor coil sends the RPM signal to the cluster, but the ECU can also control it. When converting to coil-on-plug, the signal from the distributor stops working, so the ECU must provide it.

1. Select the output Low-Side 11 to send the RPM signal.

   
   

2. If you’re still using a distributor coil and want to control the RPM by the ECU, remove the wire:

   

3. Select the TACH switch to YES.

   

Auxiliary inputs/outputs

LOW SIDE: Controls injectors and valves using a ground signal, handling up to 10A.

• L13 to L24: Configurable for any auxiliary function

HIGH SIDE: Controls smart ignition coils with 5V or 12V signals.

• H5 to H12: Configurable for any auxiliary function

ANALOG: Inputs for sensors with a 0-5V output or for temperature sensors.

• A5: Dedicated to the onboard MAP sensor.
• A9: Dedicated to the knock sensor on the OBD1 D3 terminal.
• A6, A7, A10, A12: Configurable for any auxiliary function

NOTE1: If no sensor is wired, it can be repurposed for any other function.
NOTE2: To use temperature sensors, the corresponding input switch must be set to the ON position.

DIGITAL: Inputs for hall sensors (0-5V)

• D2: Clutch switch on OBD1 B7.
• D3: AC signal on OBD1 B5.
• D4, D5, D6, D7, D8: Auxiliary inputs
• TRIGGER3: CRITICAL - Only send a ground signal! Sending other signals will damage the ECU.

NOTE1: If no sensor is wired, it can be repurposed for any other function.

SENSORS: Provides 5V output and ground for powering pressure and temperature sensors.

EGT: Inputs for exhaust temperature sensors (Type K)

Drive-by-wire: Controls a 2-wire electronic throttle body or ITB.

• A8 & A11: Analog inputs for ETB potentiometers.
• OUT- & OUT+: Output for ETB motor.
• 5V: Power to the potentiometers.
• GND: Ground to the potentiometers.

NOTE1: If no sensor is wired, it can be repurposed for any other function.

PINOUT: OBD1 DPFI

Connector A

OBD1	FUNCTION	TUNERSTUDIO
A1	Injector 1 / 4	Low side 1
A3	Injector 2 / 3	Low side 2
A5	Auxiliary: Injector 3	Low side 3
A7	Fuel pump relay	Low side 5
A9	Auxiliary: Injector 4	Low side 4
A13	CEL	Low side 6
A15	A/C clutch relay	Low side 7
A16	IACV B	Low side 9
A18	IACV A	High side 8
A22	Distributor ICM	High side 1
A25	+12V ignition
A26	Ground

Connector B

OBD1	FUNCTION	TUNERSTUDIO
B5	A/C signal	Digital input 3
B7	Clutch switch	Digital input 2
B10	Vehicle speed sensor	Digital input 1
B13	Trigger signal	VR/Hall 1 (E2)
B14	Auxiliary: Hall 2	VR/Hall 2 (E3)

Connector C

OBD1	FUNCTION	TUNERSTUDIO
C1	Low side 12	Low side 12 (G3)
C2	LSU 4.9 - PIN 5 (IA)
C3	Tachometer output	Low side 11 (G2)
C4	LSU 4.9 - PIN 6 (NERMEST)
C5	Coil 1	High side 1 (E15)
C6	LSU 4.9 - PIN 1 (IP)
C7	Coil 2	High side 2 (E14)
C8	LSU 4.9 - PIN 2 (VGND)
C9	Coil 3	High side 3 (E13)
C10	LSU 4.9 - PIN 3 (HEATER-)
C11	Coil 4	High side 4 (E12)
C12	LSU 4.9 - PIN 4 (HEATER+)

Connector D

OBD1	FUNCTION	TUNERSTUDIO
D8	Tachometer output	Low side 11 (G2)
D11	Throttle position sensor	Analog input 1
D13	Coolant temperature sensor	Analog input 2
D15	Intake air temperature sensor	Analog input 3
D17	Manifold air pressure sensor	Analog input 4
D19	+5V out 1
D20	+5V out 2
D21	MAP ground
D22	TPS ground