Design and construction of
a fault emulator for the electronic control of an internal combustion engine
via wireless interface
Diseño y construcción de
un emulador de fallas para el control electrónico de un motor de combustión
interna mediante interfaz inalámbrica
Jorge Luis Lema Loja*
Cristian David Oña Rodríguez*
Alex Rodolfo Guzmán Antamba*
ABSTRACT
Electronic
fuel injection systems have replaced carburetors due to their precise control
of the air-fuel mixture, optimizing combustion and reducing emissions. These
systems, which include sensors, actuators and the ECU, are essential to engine
performance. The complexity of these systems requires advanced diagnostic tools
and specialized training for automotive technicians. Emulators are crucial for
training, allowing practice in safe environments. Injection systems use sensors
to measure airflow, pressure, temperature and crankshaft position, sending
signals to the ECU to adjust injection and ignition. Some key sensors are the
MAF, MAP, IAT, CKP, KS and the oxygen sensor. The ECU analyzes these signals to
adjust the amount of fuel needed, improving efficiency and reducing consumption
and emissions. Therefore, this document details the design and construction of
a fault emulator for the electronic injection system for an internal combustion
engine, through the application of electronic components, PCB design in Protel
99 SE and use of Iocomp commands which will allow the
identification of faults, engine behavior and training for automotive
technicians. Fault emulation allowed the identification of faults and erroneous
behavior of the internal combustion engine.
Keywords:
actuators, emulator, faults, sensors.
RESUMEN
Los sistemas de inyección
electrónica de combustible han reemplazado a los carburadores debido a su
control preciso de la mezcla aire-combustible, optimizando la combustión y
reduciendo emisiones. Estos sistemas, que incluyen sensores, actuadores y la
ECU, son esenciales para el rendimiento del motor. La complejidad de estos
sistemas requiere herramientas de diagnóstico avanzadas y capacitación
especializada para los técnicos automotrices. Los emuladores son cruciales para
la formación, permitiendo practicar en entornos seguros.
Los sistemas de inyección usan
sensores para medir flujo de aire, presión, temperatura y posición del
cigüeñal, enviando señales a la ECU para ajustar la inyección y el encendido.
Algunos sensores clave son el MAF, MAP, IAT, CKP, KS y el sensor de oxígeno. La
ECU analiza estas señales para ajustar la cantidad de combustible necesaria,
mejorando la eficiencia y reduciendo el consumo y las emisiones. Por lo tanto,
en este documento se detalla el diseño y construcción de un emulador de fallas
para el sistema de inyección electrónico para un motor de combustión interna,
mediante la aplicación de componentes electrónicos, diseño de PCB en Protel 99
SE y uso de commandos Iocomp con lo cual permitirá la identificación de fallas,
comportamiento del motor y entrenamiento a técnicos automotrices. La emulación
de fallas permitió la identificación de fallas y comportamiento errado del
motor de combustión interna.
Palabras clave: actuadores, emulador, fallas,
sensores.
INTRODUCTION
Electronic fuel injection
(EFI) systems have largely replaced carburetors in modern vehicles due to their
ability to precisely control the air-fuel mixture, resulting in more efficient
combustion and reduced pollutant emissions (Aguilar, Gallo, Calero, &
Guerra, 2022) (González, 2012). Electronic fuel injection management, which
involves sensors, actuators, and an electronic control unit (ECU), is critical
for optimal engine performance (Aguilar et al., 2022) (González, 2012)
(Sandovalin, Correa, Guasumba, & Calero, 2022).
The increasing complexity of electronic
injection systems requires advanced diagnostic tools and specialized training
for automotive technicians (Alonso & Dos Reis Filho, 1999) (Gómez Iaconcha,
2020) (Almachi Oñate, Mena Villamarin, Ordoñez Vivero, & Reigosa Lara,
2024). Emulators have become an essential training tool, as they allow
technicians to practice diagnosis and troubleshooting in a safe and controlled
environment (González, 2012) (Byron, Borja, Isaac, & Cruz, 2023). These
emulators allow common faults in sensors and actuators to be recreated, thus
facilitating practical learning (Aguilar et al., 2022) (González, 2012)
(Almachi Oñate et al., 2024) (Fuentes Covarrubias & Fuentes Covarrubias,
2013) (Almachi Oñate et al., 2024).
This document explores the operation of
sensors in electronic injection systems, their importance in controlling fuel
consumption, and methodologies for their diagnosis and emulation. Electronic
injection systems use a variety of sensors to measure parameters such as air
flow, pressure, temperature, and crankshaft position, among others (Sandovalin et al., 2022) (Aguilar et al., 2022) (González,
2012) (Fuentes Covarrubias & Fuentes Covarrubias, 2013) These sensors send
electrical signals to the ECU, which processes this information and adjusts
fuel injection and ignition to achieve optimal combustion (Aguilar et al.,
2022) (Sandovalin et al., 2022) (Fernando
Galeano-Vergara III, Vinicio Vergara-Hidalgo, & Edison Guasumba-Maila,
2021). Practical training with fault emulators is an effective method for
teaching technicians to identify and solve problems in electronic injection
systems. This article details the design, construction, and validation of a
fault emulator for the electronic injection system of an internal combustion
engine, developed for the technical training of automotive technicians in
Ecuador. The emulator was designed to recreate common faults in the system's
sensors and actuators, allowing technicians to practice diagnosis and
troubleshooting in a safe and controlled environment [
To this end, the relevant emulations were
performed on the CMP, MAF, TPS, IAT, ECT sensors, clutch switch, neutral
switch, and actuators such as injectors and IAC valve of an internal combustion
engine. This study included the identification of their operating principles,
connection pins, control tests, operating values and adjustment specifications,
and diagrams of the engine control circuits and diagnostic connector (DLC). The
injection time was analyzed in relation to the lambda probe signal.
Key sensors in electronic injection systems:
Mass air flow (MAF) sensor: Measures the
amount of air entering the engine (Aguilar et al., 2022) (González, 2012).
Manifold absolute pressure (MAP) sensor: Measures
the pressure inside the intake manifold (González, 2012).
Intake air temperature (IAT) sensor: Measures
the temperature of the air entering the engine (Fernando Galeano-Vergara III et
al., 2021).
Crankshaft position sensor (CKP): Detects
the position and speed of the crankshaft for ignition and injection timing
(Fernando Galeano-Vergara III et al., 2021)(Aguilar et al., 2022).
Knock sensor (KS): Detects abnormal
combustion in the engine (Aguilar et al., 2022).
Oxygen sensor (Lambda): Measures the
amount of oxygen in the exhaust gases (Aguilar et al., 2022) (Sandovalin et al., 2022)
The operation of an engine depends on the
electrical signals sent by these sensors to the ECU, which analyzes the
information and adjusts the actuators for optimal performance (Aguilar et al.,
2022). Unlike carburetors, electronic fuel injection systems allow the exact
amount of fuel needed for combustion to be determined, resulting in greater
engine efficiency, lower fuel consumption, and reduced emissions (González,
2012) (Aguilar et al., 2022) (Sandovalin et al.,
2022) (Sandovalin et al., 2022).
Electronic fuel injection systems can be
classified according to several criteria:
Number of injectors: they can be
single-point or multi-point, with one injector per cylinder (Aguilar et al.,
2022).
Injector location: they can be direct or
indirect injection, where the fuel is injected directly into the combustion
chamber or into the intake manifold, respectively (Aguilar et al., 2022) (Sandovalin et al., 2022).
Injector timing: They can be sequential,
where each injector is activated at the precise moment, or simultaneous, where
several injectors are activated at the same time (Aguilar et al., 2022).
MATERIALS
AND METHODS
The methodology used in this project was divided into
several stages, such as: study of sensors and actuators, design and
construction of the emulator, software development, and validation testing. The
main phases of this process are described below:
Printed Circuit Board Design
The printed circuit board (PCB) was designed using
Protel 99 SE software. This software enabled the creation of electronic
schematics, layout design, and the generation of files for PCB manufacturing.
The PCB included: 12 relays for switching sensors and actuators (ECT, IAT, TPS,
injectors, IAC, PCM power and ground, ignition, start), 3 BJT transistors to
simulate the clutch pedal position switches, power steering switches, and
neutral switch, 3 digital potentiometers for varying the signals from the ECT,
IAT, and TPS sensors, 1 MOSFET for the IAC valve flicker signal, 2 PIC 16F877A
microcontrollers for simulation control and management, 2 transmitters for
wireless communication with the control software on the PC, and regulators,
capacitors, oscillators, resistors, diodes, and other support components.
Figure 1 shows the emulation circuits for each of the sensors and actuators.
Figure 2 shows the electronic circuit design in Protel 99 SE. Figure 3 shows
the track design for the Main Board and Transmission.
Figure 1. Circuits
for emulating faults in the main sensors and actuators a) CMP, b) MAF, Neutral
Switch, i) Inyectores
|
a) |
b) |
c) |
|
d) |
e) |
f) |
|
g) |
h) |
j) |
Figure
2.
Electronic Circuit Design
Microcontroller Programming
Two PIC 16F877A microcontrollers were programmed using
a specific programming language for microcontrollers. The first microcontroller
acted as the master, receiving commands from the software and sending signals
to the second microcontroller, which controls the relays, potentiometers, and
transistors in the power stage. The main microcontroller reads the sensor
signals and sends the data to the slave microcontroller, which controls the
relays and transistors to simulate the faults.
Software Development
Software was developed in Visual Basic Studio to
control the simulator. This software included two main windows:
“Engine” window: For selecting the simulations to be
performed on the sensors and actuators, with the help of combo boxes. Figure 3
shows the “Engine” window.
Figure 3. “Engine”
window
‘Dashboard’ window: For viewing the engine status in
terms of parameters such as revolutions, temperature, fuel level, among others,
using Iocomp commands to create indicators and
gauges. Figure 4 shows the “Dashboard” window.
Figure 4.
“Dashboard” window
“Main” window: For selecting the communication port
and accessing the “Engine” and “Dashboard” windows. Figure 5 shows the ‘Main’
window.
Figure 5.
“Main” window
Control Circuit Adaptation
The necessary connections were made between the PCB
and the engine sensors and actuators. Relays were used to simulate signal
interruptions, and digital potentiometers were used to vary the analog signals
from the resistive sensors (ECT, IAT, TPS). Figure 6 shows the PCB prior to
installation with the sensors, actuators, and PCM.
Figure 6.
Finished PCB board
Simulator operation
1. The
instructor selects a specific simulation from the software on the computer.
2. The
software sends the command to the microcontroller via radio frequency.
3. The
microcontroller on the PCB activates the corresponding circuit (relays,
transistors, potentiometers).
4. The
circuit simulates the failure in the sensor or actuator, sending an altered
signal to the PCM.
5. The
technician can analyze the engine's response and diagnose the fault using
diagnostic tools.
Figure 8 shows a general diagram of how the emulator
works.
RESULTS
Extensive testing was conducted to validate the
simulator's operation. Different types of sensor and actuator failures were
simulated, and the control system's response and the generation of the
corresponding fault codes were verified using an automotive multimeter and an
automotive scanner.
Validation with Diagnostic Equipment
The voltage values of the sensors and actuators were
measured with an automotive multimeter, and the fault codes were verified with
an automotive scanner.
The fault generation equipment built allowed the
emulation of different fault scenarios in the Mazda G6 engine injection system.
Some of the simulations performed are shown below:
Sensor Fault Simulation
MAF Sensor: The sensor disconnection was simulated,
obtaining a reading of 0.05 V, which resulted in fault code P0100 (MAF CIRCUIT
FAULT). Figure 7 shows the voltage presented by the fault.
Figure 7. Voltage
obtained by disconnecting the MAF sensor
IAT Sensor: Intermittent faults, disconnection (with a
reading of 5.01 V), and temperature signal variation were simulated. Fault code
P1110 (TEMPERATURE AIR INTAKE CIRCUIT – OPEN/SHORT) was obtained. Figure 8
shows the voltage presented by the fault.
Figure 8. Voltage
obtained by disconnecting the IAT sensor
ECT sensor: Intermittent faults, disconnection, and
temperature signal variation were simulated.
The latter varied the voltage outside the upper range,
with a fault code of P0118 and a voltage value of 4.96 V. Figure 9 shows the
voltage presented by the fault.
Figure 9. Voltage
outside the upper range of the ECT sensor
TPS Sensor: Intermittent faults, disconnection, and
variation of the throttle position signal were simulated. The latter varied the
voltage outside the minimum range, with a fault code of P0122 and a voltage
value of 0.03 V. Figure 10 shows the voltage presented by the fault.
Figure 10. Voltage
out of lower range TPS sensor
Switches: The closing and opening signals of the
clutch, neutral, and CTP switches were simulated, showing changes in engine
speed and, therefore, engine load.
CMP sensor: The cut-off and closure of the camshaft
position sensor signal was emulated, which showed the engine shutting down
during this simulation.
Actuator Failure Simulation
Injectors: A power supply defect was simulated by
reducing the input voltage to the injectors to 11.7 V, which generated a delay
in the opening of the injector of 0.53 ms, implying a
loss of injection of 26.5%. Figure 10 shows the variation in the voltage supply
to the injectors.
IAC valve: Valve activation and deactivation were
simulated, allowing changes in the idle speed to be observed. The figure
simulates the IAC at low load, generating a voltage of 7.27 V, evidencing an
unstable idle speed.
Benefits of the emulator
Hands-on training: Allows technicians to experiment
with simulated faults in a safe environment.
Improved reasoning: Encourages logical reasoning in
fault diagnosis.
Reduced maintenance time: Allows faults to be
identified more quickly and efficiently.
Fault database: Allows the creation of a database of
faults and their respective solutions.
Adaptability: The simulator can be adapted to other
Mazda engines with software modifications.
DISCUSSION
The fault simulator developed in this project proved
to be an effective tool for technical training on the Mazda G6 BT-50 engine's
electronic injection system. The results obtained validated the simulator's
design, construction, and operation. The main conclusions are:
A simulator was successfully designed and built that
accurately recreates common faults in the electronic injection systems of the
Mazda G6 BT-50 engine.
The PCB designed and implemented worked correctly,
managing the switching and variation of sensor and actuator signals.
The control software developed in Visual Basic allowed
intuitive interaction with the simulator, facilitating the selection and
execution of simulations.
The use of microcontrollers and wireless communication
allowed for efficient management of the simulator.
The emulator was built to the actual scale of the
Mazda BT-50 pickup truck engine compartment, providing a realistic learning
environment.
The simulator facilitates the identification of error
codes using an automotive scanner, simulating electrical faults such as high,
low, no, and intermittent signals, allowing for an understanding of the
possible causes of engine faults.
The simulator can be adapted to other electronic
injection engines by reprogramming the software.
The validation of sensor and actuator signals with
real diagnostic equipment (multimeter, scanner) ensured the accuracy of the
simulations.
REFERENCES
Aguilar, C. D., Gallo, E. M.,
Calero, D. A., & Guerra, J. I. (2022). Análisis del funcionamiento en los
sensores de inyección electrónica para controlar el consumo de combustible. Dominio
de las Ciencias, 8(2), 451–769. https://www.dominiodelasciencias.com/ojs/index.php/es/article/view/2673
Almachi Oñate, R. R., Mena
Villamarín, D. A., Ordóñez Vivero, R. E., & Reigosa Lara, A. (2024).
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https://doi.org/10.55204/trc.v4i1.e387
Alonso, G. C. M. B., & Dos
Reis Filho, C. A. (1999). Automotive simulator for electronic fuel injections.
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10, pp. 1552–1567). (Nota: referencia incompleta; se recomienda revisar
nombre de la revista o editorial).
Galeano-Vergara III, H. F.,
Vergara-Hidalgo, E. I. V., & Guasumba-Maila, J. I. E. (2021). El control
y la gestión de la inyección electrónica de combustible para los motores de
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Gómez Iaconcha, J. R. (2020).
Sistema de emulación fuera del vehículo de ECUs de control del motor para su
diagnóstico posterior. Tknika, 3. https://www.ni.com/es/innovations/case-studies/19/system-of-emulation-outside-the-vehicle-of-engine-control-ecus-for-their-subsequent-diagnosis.html
González, H. E. C. (2012). Diseño
de un simulador de señales básicas para un sistema de inyección electrónica
de gasolina [Trabajo de titulación].
Sandovalin, J., Correa, E.,
Guasumba, J., & Calero, D. (2022). Los sistemas de inyección electrónicos
y el control de gases. Polo del Conocimiento, 7(69),
344–361. https://doi.org/10.23857/pc.v7i4.3828
Ingeniero en Mecánica Automotriz. Magíster
en Sistemas Automotrices.
Docente Investigador Universidad UTE. Grupo
de investigación GIIVE
https://orcid.org/0000-0002-1515-4526
Ingeniero en Mecánica Automotriz.
Doctor en Educación. Docente Universidad
Internacional del Ecuador
https://orcid.org/0009-0004-5007-462X
Ingeniero Mecánico. Magíster en Sistemas
Automotrices. Docente Investigador Universidad UTE. Grupo de investigación
GIIVE
https://orcid.org/0000-0001-7842-0302