Powertrain Management: Description and Operation

GENERAL INFORMATION
The Multi port Fuel Injection System consists of sensors which detect the engine conditions, the ENGINE CONTROL MODULE (ECM) which controls the system based on signals from these sensors and actuators which operate under the control of the ECM.
The ECM carries out activities such as fuel injection control, idle air control and ignition timing control. In addition, the ECM is equipped with several diagnostic test modes which simplify troubleshooting when a problem develops.

FUEL INJECTION CONTROL
The injector drive times and injector timing are controlled so that the optimum air/fuel mixture is supplied to the engine to correspond to the continually-changing engine operation conditions. A single injector is mounted at the intake port of each cylinder. Fuel is sent under pressure from the fuel tank to the fuel injectors by the fuel pump, with the pressure being regulated by the fuel pressure regulator. The regulated fuel is distributed to each of the injectors.
Fuel injection is normally carried out once for each cylinder for every two rotations of the crankshaft. The firing order is 1-3-4-2. Each cylinder has a dedicated fuel injector. This is called multiport. The ECM provides a richer air/fuel mixture by carrying out "open-loop" control when the engine is cold or operating under high load conditions in order to maintain engine performance.
In addition, when the engine is under normal operating temperature after warming-up, the ECM controls the air/fuel mixture by using the heated oxygen sensor signal to carry out "closed-loop" control. The closed-loop control achieves the theoretical air/fuel mixture radio where the catalytic converter can obtains the maximum cleaning performance.

IDLE AIR CONTROL
The idle speed is kept at the optimum speed by controlling the amount of air that bypasses the throttle valve in accordance with changes in idling conditions and engine load during idling.
The ECM drives the idle air control (IAC) motor to keep the engine running at the pre-set idle target speed in accordance with the engine coolant temperature and air conditioning load. In addition, when the air conditioning switch is turned off and on while the engine is idling, the IAC motor adjusts the throttle valve bypass air amount according to the engine load conditions to avoid fluctuations in the engine speed.

IGNITION TIMING CONTROL
The ignition power transistor located in the ignition primary circuit turns ON and OFF to control the primary current flow to the ignition coil. This controls the ignition timing to provide the optimum ignition timing with respect to the engine operating conditions. The ignition timing is determined by the ECM from the engine speed, intake air volume, engine coolant temperature and atmospheric pressure.

DIAGNOSTIC TEST MODE
- When an abnormality is detected in one of the sensors or actuators related to emission control, the CHECK ENGINE/MALFUNCTION INDICATOR LAMP illuminates to warn the driver.
- When an abnormality is detected in one of the sensors or actuators, a diagnostic trouble code corresponding to the abnormality is stored in the ECM.
- The RAM data inside the ECM that is related to the sensors and actuators can be read with the scan tool.
In addition, the actuators can be controlled by the scan tool (MUT-II) under certain circumstances.

OTHER CONTROL FUNCTIONS
1. Fuel Pump Control
Turns the fuel pump relay ON so that current is supplied to the fuel pump while the engine is cranking or running.
2. A/C Compressor Clutch Relay Control
Turns the compressor clutch of the A/C ON and OFF.
3. Fan Relay Control
The radiator fan and condenser fan speeds are controlled in response to the engine coolant temperature and vehicle speed.
4. Evaporative Emission Purge Control
(Refer to GROUP 17.)
5. EGR Control
(Refer to GROUP 17.)

General Specification
Items Specifications
Throttle body
Throttle bore mm (in.) 50 (1.97)
Throttle position sensor Variable resistor type
Idle air control motor Stepper motor (Stepper motor type by-pass air control system with the air volume limiter)
Closed throttle position switch Rotary contact type, within throttle position sensor
Idle air control valve position sensor Hall element type
Engine control module (ECM) Identification model No.
E2T65688
E2T65687
Sensors
Volume air flow sensor Karman vortex type
Barometric pressure sensor Semiconductor type
Intake air temperature sensor Thermistor type
Engine coolant temperature sensor Thermistor type
Heated oxygen sensor Zirconia type
Vehicle speed sensor Electromagnetic resistance element type
Park/Neutral position switch Contact switch type
Camshaft position sensor Hall element type
Crankshaft position sensor Hall element type
Power steering pressure switch Contact switch type
Actuators
Multiport fuel injection (MFI) relay Contact switch type
Fuel pump relay Contact switch type
Injector type and number Electromagnetic type, 4
Injector identification mark CDH210
EGR solenoid Duty cycle type solenoid valve
Evaporative emission purge solenoid Duty cycle type solenoid valve
Fuel pressureregulator Regulator pressure kPa (psi) 335 (47.6)

MULTIPORT FUEL INJECTION (MFI) SYSTEM DIAGRAM