AIR INDUCTION SYSTEM - TRIPLE INDUCTION CONTROL SYSTEM (TICS 929 ONLY)
All 3.0L engine cylinder heads have 3 valves per cylinder, 2 intake and 1 exhaust. To improve intake efficiency at idle and low engine speeds, the TICS closes a swirl control valve in the intake runners. This causes most of the intake air to be forced through a small passage called a swirl port located below main intake manifold runner. This causes strong swirl in the combustion chamber to improve combustion and fuel economy.
Scheme 2
AIR INDUCTION SYSTEM - VARIABLE RESONANCE INDUCTION SYSTEM (VRIS 3.0L ONLY)
A shutter valve in the dynamic chamber changes intake runner length depending upon engine RPM. To improve low speed torque output, intake runners are lengthened. At about 3700 RPM, shutter valve changes intake runners to shorter length to improve high RPM performance.
Scheme 3
ELECTRONIC FUEL INJECTION
The Mazda Electronic Gas Injection (EGI) computerized engine control system monitors various engine/vehicle functions to control engine operation and lower emissions while maintaining good fuel economy and driveability.
The Electronic Control Unit (ECU), through various input sensors, monitors battery voltage, engine RPM, intake air volume, cranking signal, crankshaft angle, intake air temperature, radiator and engine coolant temperatures, exhaust oxygen content, throttle position, atmospheric pressure, gearshift lever position, clutch engagement, braking, power steering operation, and A/C compressor operation. The ECU uses this input information in determining fuel injection and the actuation of other output devices. On 929 models spark timing is controlled by the ECU.
The ECU has a built-in fail-safe mechanism. If a fault occurs while driving, the ECU will substitute pre-programmed values. Driving performance will be affected, but the vehicle may still be driven.
The ECU has a self-diagnostic function which allows the unit to store a number of trouble codes in its memory. A Malfunction Indicator Lamp (MIL) informs the driver of system problems. The MIL is in the center of the instrument cluster, under the engine symbol marked "CHECK".
Air Conditioning Switch
Closes when A/C or blower is in the "ON" position.
Airflow Meter (Inlet Air Temperature)
Varies voltage signal to ECU in relation to inlet air temperature.
Airflow Meter (Vc)
Corrected airflow meter voltage.
Airflow Meter (Vs)
Airflow position signal.
Atmospheric Pressure Sensor
Varies voltage signal according to altitude.
Brake Light Switch
Signals ECU of vehicle braking condition.
Coolant Temperature Sensor
Varies input voltage signal according to engine coolant temperature.
Coolant Temperature Switch
Switch opens and closes according to radiator temperature.
Distributor Signal
Signals cylinder TDC (No. 1 and 4 on V6 engines) for fuel injection timing. Detects crankshaft angle at 30 degree intervals.
EGR Position Sensor (929 Only)
Signals EGR valve opening quantity.
Electrical Load Control
Signals ECU of additional electrical load.
Idle Switch
Indicates throttle open or closed position.
Ignition Coil
Signals engine speed.
Ignition Switch
Supplies battery voltage to ECU during engine cranking.
Ignitor (3.0L Only)
Signals engine speed.
Inhibitor Switch (A/T)
Signals ECU of gear selection.
Intake Air Temperature Sensor (Dynamic Chamber 3.0L Only)
Varies voltage signal to ECU in relation to engine air temperature. All 929 models use 2 intake air temperature sensors. One sensor is located inside the airflow meter, the other is located near the intake runner on cylinder head.
Knock Sensor (Turbo Only)
Sends signal to knock control unit which retards ignition timing when knocking occurs.
Main Relay
Provides battery voltage to ECU.
Neutral/Clutch Switch (M/T)
Signals ECU of clutch operation and transaxle gear selection.
Oxygen (O2) Sensor
Generates voltage signal depending on oxygen content of exhaust.
Throttle Sensor
Referred to as PSW switch. Provides signal in response to wide open throttle position.
OUTPUT SIGNALS - ELECTRONIC FUEL INJECTION
The ECU processes information from the input sensors and sends appropriate voltage control signals to the following engine controls
- By-Pass Air Control (BAC) Valve (Idle Speed)
- "CHECK ENGINE" Light (Self-Diagnostics)
- EGR Solenoid (Emission)
- Fuel Injectors (Fuel Supply)
- Fuel Pump Relay (Fuel Delivery)
- Idle Speed Control Valve (Idle Speed)
- Ignitor (Ignition)
- Knock Control Unit (Turbo Only - Ignition)
- Pressure Regulator Control Solenoid (Fuel Supply)
- Purge Control Solenoid (Emission)
- Triple Induction Control System (TICS) Solenoid (929 Only - Air Induction)
- Variable Resonance Induction System (VRIS) Solenoid (3.0L Only - Air Induction)
- Voltage Reference (Pin Voltage)
Fuel Pump
Fuel under pressure from electric fuel pump flows through a fuel damper, fuel filter, injector fuel rail and fuel pressure regulator. Fuel pump is located in fuel tank. Electrical power for fuel pump operation during cranking mode is provided from starter relay via the fuel pump relay and ECU.
Fuel Pump Relay
The ECU turns on the fuel pump relay based on inputs from the ignition switch and the ignition coil. During cranking, the ignition switch cranking circuit supplies current to energize the fuel pump relay. After engine starts and key is released to "RUN" position (engine speed more than 50 RPM), ECU provides fuel pump relay ground. This activates fuel pump.
Fuel Pressure Regulator
The pressure regulator is a sealed unit which is divided by a diaphragm into 2 chambers (fuel and spring chambers). The fuel chamber receives fuel through the inlet side from the injector fuel rail. The spring chamber is connected to intake manifold vacuum.
At idle, intake manifold vacuum is high. The diaphragm is pulled back by intake manifold vacuum. Any excessive fuel is returned to the fuel tank. As the throttle is depressed, intake manifold vacuum decreases. The regulator spring overcomes manifold vacuum increasing fuel pressure.
The Electronic Gasoline Injection (EGI) fuel injection system is an electronically controlled system operated by incoming air flow. The EGI fuel injection system also contains a feedback system which measures oxygen content of exhaust gases and maintains the air/fuel ratio at about 14.7:1.
The EGI fuel injection system consists of 3 major sub-systems. These are the air intake system, the fuel system, and the ECU.
A/C Cut-Out System
During acceleration (60 percent throttle or more) and just after starting the engine, the ECU will open the A/C relay thereby cutting off the A/C compressor clutch. This is done to improve idle just after starting the engine and improve acceleration performance.
Under acceleration, the A/C will be cut off when the throttle valve is more than half open, transmission is in gear, and clutch pedal is released (man. trans. only). A/C is cut off for about 10 seconds. A/C will also be cut off for about 5 seconds after the engine is started.
By-Pass Air Control (BAC) Valve
The BAC valve contains an air valve and Idle Speed Control (ISC) valve. Engine coolant is directed around the air valve warming up the thermo wax. When engine coolant temperature is less than 122°F (50°C), the wax is contracted and the engine idles fast. When coolant temperature is more than 122°F (50°C), the wax is fully expanded, closing valve.
The Idle Speed Control (ISC) valve controls air by-pass amount during cold and warm engine operation. During cold engine operation, the ISC valve opens, raising fast idle speed to a predetermined RPM. The ISC valve also compensates for all engine loads during warm engine operation to maintain a preset idle RPM. The ISC is controlled by the ECU.
Scheme 4
ELECTRONIC IGNITION SYSTEM
Mitsubishi breakerless electronic ignition consists of an ignitor, ignition coil, pick-up coil and distributor. The control module is mounted inside the distributor with the pick-up coil assembly.
When ignition is on, ignition coil primary circuit is energized. As distributor shaft rotates, the reluctor rotates inside the stator assembly.
As armature teeth pass the pegs of the pick-up coil, a signal is sent to the ignitor. The ignitor then breaks the primary circuit in the coil. This causes a high voltage surge in the coil secondary circuit. This high voltage is required to fire the spark plugs.
Ignition Timing Advance Control
929 use an Electronic Spark Advance (ESA) that is ECU controlled. The ECU determines ignition timing based on signals from the various sensors and switches. MPV models use centrifugal and vacuum advance units located in the distributors.
Detonation (Knock) Retard Operation
Turbocharged models use a ignition retard system consisting of a knock sensor and knock control unit. The knock sensor detects detonation in the engine and sends a signal to knock control unit. This signal is modified by the knock control unit and sent to the ECU. Timing is retarded up to 6 degrees, depending upon severity of knocking.
DECELERATION CONTROL SYSTEM
Slow fuel-cut solenoid valve closes primary slow fuel passage on command from ECU. Coasting richer solenoid valve supplies extra fuel/air mixture to add to primary slow fuel on command from ECU. Vacuum solenoid valve supplies intake manifold vacuum to distributor vacuum advance on command from ECU. Dashpot causes throttle valve to close gradually. Mixture control valve supplies air into intake during first stage of deceleration.
EXHAUST GAS RECIRCULATION (EGR) CONTROL
The Exhaust Gas Recirculation (EGR) system allows measured amounts of exhaust gas into the intake manifold to reduce oxides of nitrogen (NOx).
The EGR system on 929 models consists of EGR control valve, EGR solenoid valves (vacuum side and vent side), EGR position sensor, and connecting hoses and pipes.
FUEL EVAPORATION SYSTEM
Fuel evaporation system prevents escape of raw fuel vapor to atmosphere. Components of system include a fuel tank with integral vapor separator, a check and cut valve, a charcoal canister, a fuel filler cap, a coolant thermovalve (929), and connecting lines.
Additional components include, a 2-way solenoid valve on 929, and Emission Control Unit (ECU).
THERMOSTATIC AIR CLEANER
The Thermostatic Air Cleaner system controls the temperature of the air entering the carburetor depending on outside air temperature.
A control valve, controlled by air temperature, opens to allow warm air from heat stove to mix with fuel. This assists in engine warm up, better combustion and emission control.
CHECK ENGINE LIGHT
Lights during engine start up and monitored component malfunction. Is also referred to as MIL or Malfunction Indicator Light. MIL is also used to read trouble codes.