Fuel and Emissions System Description

Electronic Control System


The functions of the fuel and emission control systems are managed by the Engine Control Module (ECM).

Fail-safe Function

When an abnormality occurs in a signal from a sensor, the ECM ignores that signal and assumes a pre-programmed value for that sensor that allows the engine to continue to run.

Back-up Function

When an abnormality occurs in the ECM, the injectors are controlled by a back-up circuit independent of the system to permit minimal driving.

Self-diagnosis

When an abnormality occurs in the signal from a sensor, the ECM supplies ground for the Malfunction Indicator Lamp (MIL) and stores the Diagnostic Trouble Code (DTC) in erasable memory. When the ignition is first turned on, the ECM supplies ground for the MIL for 2 seconds to check the MIL bulb condition.

Two Driving Cycle Detection Method

To prevent false indications, the ‘‘two driving cycle detection method'' is used for some self-diagnostic functions. When an abnormality occurs, the ECM stores it in its memory. When the same abnormality recurs after the ignition switch is turned OFF and ON (II) again, the ECM informs the driver by turning on the MIL.

Self Shut Down Mode (SSD)

After the ignition switch is turned off, ECM stays ON (Up to 10 seconds).
If the ECM connector is disconnected during this mode, ECM may be damaged.
If you need to disconnet the ECM connector, disconnect the negative cable from the battery, or wait for 10 seconds after turning the ignition switch off.

ECM Inputs and Outputs at Connector No. 1 (9P)

 

NOTE: Standard battery voltage is 12 V.

ECM Terminal number Pin Box Terminal number Wire color Terminal name Description Signal 
BRN PG1 (POWER GROUND) Ground for ECM circuit Less than 1.0 V at all times 
BRN PG2 (POWER GROUND) Ground for ECM circuit Less than 1.0 V at all times 
WHT/RED UBD (POWER SOURCE) Power source for ECM circuit Battery voltage at all times 
BRN/YEL LG3 (LOGIC GROUND) Ground for ECM circuit Less than 1.0 V at all times 

ECM Inputs and Outputs at Connector No. 3 (52P)

 

NOTE: Standard battery voltage is 12 V.

ECM Terminal number Pin Box Terminal number Wire color Terminal name Description Signal 
30 BRN/YEL CKPG (CRANKSHAFT POSITION (CKP) SENSOR GROUND) Ground for CKP sensor Less than 1.0 V at all times 
32 BLU/RED VCC4 (SENSOR VOLTAGE) Provides sensor voltage With ignition switch ON (II): about 5 V
With ignition switch OFF: 0 V 
33 YEL/GRN VCC3 (SENSOR VOLTAGE) Provides sensor voltage With ignition switch ON (II): about 5 V
With ignition switch OFF: 0 V 
34 WHT/GRN ALTC (ALTERNATOR CONTROL) Sends alternator control signal With engine running and fully warmed up:
batter voltage (depending on electrical load) 
35 GRN CMP (CAMSHAFT POSITION (CMP) SENSOR) Detects CMP sensor signal With engine running: pulses 
36 WHT/BLK IGPLS3E (No. 3 REAR IGNITION COIL PULSE) Drives No. 3 rear ignition coil With ignition switch ON (II): 0 V
With engine running: pulses 
37 WHT/GRN IGPLS2E (No. 2 REAR IGNITION COIL PULSE) Drives No. 2 rear ignition coil 
38 WHT IGPLS1I (No. 1 FRONT IGNITION COIL PULSE) Drives No. 1 front ignition coil 
10 39 BRN INJ1 (No. 1 INJECTOR) Drives No. 1 injector At idle: duty controlled 
11 40 BLU INJ3 (No. 3 INJECTOR) Drives No. 3 injector 
12 41 YEL INJ4 (No. 4 INJECTOR) Drives No. 4 injector 
13 42 RED INJ2 (No. 2 INJECTOR) Drives No. 2 injector 
14 43 BLU CKP (CRANKSHAFT POSITION (CKP) SENSOR) Detects CKP sensor signal With engine running: pulses 
16 45 YEL/BLU VCC2 (SENSOR VOLTAGE) Provides sensor voltage With ignition switch ON (II): about 5 V
With ignition switch OFF: 0 V 
17 46 YEL/RED VCC1 (SENSOR VOLTAGE) Provides sensor voltage With ignition switch ON (II): about 5 V
With ignition switch OFF: 0 V 
19 48 WHT/RED ALTF (ALTERNATOR FR SIGNAL) Detects alternator FR signal With engine running: 0 V-5 V (depending on electrical load) 
20 49 WHT IGPLS1E (No. 1 REAR IGNITION COIL PULSE) Drives No. 1 rear ignition coil With ignition switch ON (II): 0 V
With engine running: pulses 
21 50 WHT/BLU IGPLS4E (No. 4 REAR IGNITION COIL PULSE) Drives No. 4 rear ignition coil 
22 51 WHT/BLK IGPLS3I (No. 3 FRONT IGNITION COIL PULSE) Drives No. 3 front ignition coil 
23 52 WHT/GRN IGPLS2I (No. 2 FRONT IGNITION COIL PULSE) Drives No. 2 front ignition coil 
24 53 WHT/BLU IGPLS4I (No. 4 FRONT IGNITION COIL PULSE) Drives No. 4 front ignition coil 
25 54 GRN FANC (RADIATOR FAN CONTROL) Drives radiator fan relay With radiator fan running: about 0 V
With radiator fan stopped: battery voltage 

ECM Inputs and Outputs at Connector No. 3 (52P)

 

NOTE: Standard battery voltage is 12 V.

ECM Terminal number Pin Box Terminal number Wire color Terminal name Description Signal 
26 55 YEL/BLU PCS (EVAPORATIVE EMISSION (EVAP) CANISTER PURGE VALVE) Drives EVAP canister purge valve With engine running, engine coolant below 40°C (104°F): battery voltage
With engine running, engine coolant above 40°C (104°F): duty controlled 
29 58 GRN/BLK SG3 (SENSOR GROUND) Sensor ground Less than 1.0 V at all times 
30 59 GRN/BLK SG4 (SENSOR GROUND) Sensor ground Less than 1.0 V at all times 
31 60 GRN/WHT SG1 (SENSOR GROUND) Sensor ground Less than 1.0 V at all times 
32 61 GRN/YEL PHO2SG (PRIMARY HEATED OXYGEN SENSOR (PRIMARY HO2S, SENSOR 1) GROUND) Ground for primary HO2S (sensor 1) Less than 1.0 V at all times 
33 62 GRN/BLK SG2 (SENSOR GROUND) Sensor ground Less than 1.0 V at all times 
34 63 GRN APSA (ACCELERATOR PEDAL POSITION (APP) SENSOR A) Detects APP sensor A signal With ignition switch ON (II) and accelerator pedal pressed: 4.1 V
With ignition switch ON (II) and accelerator pedal released: 0.6 V 
35 64 GRN/RED MAP (MANIFOLD ABSOLUTE PRESSURE (MAP) SENSOR) Detects MAP sensor signal With ignition switch ON (II): about 3 V
At idle: about 1.0 V (depending on engine speed) 
36 65 BLU TPSA (THROTTLE POSITION (TPS) SENSOR A) Detects TPS sensor A signal With ignition switch ON (II) and throttle fully open: 4.7 V
With ignition switch ON (II) and throttle fully closed: 0.1 V 
39 68 WHT/BLK EGRP (EXHAUST GAS RECIRCULATION (EGR) VALVE POSITION SENSOR) Detects EGR valve position sensor signal With engine running: 1.2 V-2.0 V (depending on EGR valve lift) 
40 69 YEL KS1 (KNOCK SENSOR) Detects knock sensor signal With engine knocking: pulses 
41 70 GRY/RED KS2 (KNOCK SENSOR) Ground for knock sensor Less than 1.0 V at all times 
42 71 BLK VSSG (VEHICLE SPEED SENSOR (VSS) GROUND) Ground for VSS Less than 1.0 V at all times 
44 73 WHT/GRN VSS (VEHICLE SPEED SENSOR (VSS)) Detects VSS signal With ignition switch ON (II) and front wheels rotating: cycles 0 V-about 5 V or battery voltage 
46 75 BRN/YEL CMPG (CAMSHAFT POSITION (CMP) SENSOR GROUND) Ground for CMP sensor Less than 1.0 V at all times 
47 76 WHT PHO2S (PRIMARY HEATED OXYGEN SENSOR (PRIMARY HO2S) SENSOR 1) Detects primary HO2S sensor (sensor 1) signal With throttle fully opened from idle with fully warmed up engine: about 0.6 V
With throttle quickly closed: below 0.4 V 

ECM Inputs and Outputs at Connector No. 3 (52P)

 

NOTE: Standard battery voltage is 12 V.

ECM Terminal number Pin Box Terminal number Wire color Terminal name Description Signal 
48 77 GRN/BLK SG5 (SENSOR GROUND) Sensor ground Less than 1.0 V at all times 
49 78 YEL TPSB (THROTTLE POSITION (TPS) SENSOR B) Detects TPS sensor B signal With ignition switch ON (II) and throttle fully open: 4.9 V
With ignition switch ON (II) and throttle fully closed: 0.1 V 
50 79 RED APSB (ACCELERATOR PEDAL POSITION (APP) SENSOR B) Detects APP sensor B signal With ignition switch ON (II) and accelerator pedal pressed: 2.3 V
With ignition switch ON (II) and accelerator pedal released: 0.2 V 
51 80 RED/YEL IAT (INTAKE AIR TEMPERATURE (IAT) SENSOR) Detects IAT sensor signal With ignition switch ON (II): about 0.1-4.8 V (depending on intake air temperature) 
52 81 RED/WHT ECT (ENGINE COOLANT TEMPERATURE (ECT) SENSOR) Detects ECT sensor signal With ignition switch ON (II): about 0.1-4.8 V (depending on engine coolant temperature) 

ECM Inputs and Outputs at Connector No. 4 (40P)

 

NOTE: Standard battery voltage is 12 V.

ECM Terminal number Pin Box Terminal number Wire color Terminal name Description Signal 
82 GRN/WHT FUP (FUEL INJECTION SIGNAL) Sends fuel injection signal to gauge assembly With ignition switch ON (II): pulses 
83 GRN MTRTW Sends engine coolant temperature signal With ignition switch ON (II): pulses 
85 RED/WHT K-LINE Sends and receives HDS signal With ignition switch ON (II): pulses or battery voltage 
87 RED/BLU IMOCD (IMMOBILIZER CODE) Detects immobilizer signal  
90 GRN/YEL IMOFPR (IMMOBILIZER FUEL PUMP RELAY) Drives PGM-FI main relay 2 0 V for 2 seconds after turning ignition switch ON (II), then battery voltage 
10 91 GRN/ORN MIL (MALFUNCTION INDICATOR LAMP) Drives MIL With MIL turned ON: about 0 V
With MIL turned OFF: battery voltage 
11 92 RED/YEL MRLY (PGM-FI MAIN RELAY) Drives PGM-FI main relay 1 Power source for the DTC memory With ignition switch ON (II): about 0 V
With ignition switch OFF: battery voltage 
17 98 BRN/YEL LG1 (LOGIC GROUND) Ground for ECM circuit Less than 1.0 V at al times 
18 99 BLU NEP (ENGINE SPEED PULSE) Outputs engine speed pulse With engine running: pulses 
19 100 RED ACC (A/C CLUTCH RELAY) Drives A/C clutch relay With compressor ON: about 0 V
With compressor OFF: battery voltage 
21 102 PNK SHO2SG (SECONDARY HEATED OXYGEN SENSOR (SECONDARY HO2S), SENSOR 2 GROUND) Ground for secondary HO2S (sensor 2) Less than 1.0 V at all times 
22 103 WHT/BLU BKPD (BRAKE PEDAL POSITION SWITCH) Detects brake pedal position switch signal With ignition switch ON (II) and brake pedal released: battery voltage
With ignition switch ON (II) and brake pedal pressed: about 0 V 
23 104 WHT/RED SHO2S (SECONDARY HEATED OXYGEN SENSOR (SECONDARY HO2S, SENSOR 2) Detects secondary HO2S (sensor 2) signal With throttle fully opened from idle with fully warmed up engine: about 0.6 V
With throttle quickly closed: below 0.4 V 

ECM Inputs and Outputs at Connector No. 4 (40P)

 

NOTE: Standard battery voltage is 12 V.

ECM Terminal number Pin Box Terminal number Wire color Terminal name Description Signal 
27 108 YEL/BLK IG1 (IGNITION SIGNAL) Detects ignition signal With ignition switch ON (II): battery voltage
With ignition switch OFF: 0 V battery voltage 
31 112 BLU/WHT ACS (A/C SWITCH SIGNAL) Detects A/C switch signal With A/C switch ON: 0 V
With A/C switch OFF: about 5 V 
32 113 BRN SCS (SERVICE CHECK SIGNAL) Detects service check signal With the service check signal shorted with the HDS: about 0 V
With the service check signal opened: about 5 V battery voltage 
34 115 GRN/RED ELD (ELECTRICAL LOAD DETECTOR (ELD)) Detects ELD signal With ignition switch ON (II): about 0.1-4.8 V (depending on electrical load) 
36 117 WHT/BLK BKSW (BRAKE PEDAL POSITION SWITCH) Detects brake pedal position switch signal With brake pedal released: about 0 V
With brake pedal pressed: battery voltage 
39 120 BRN/YEL LG2 (LOGIC GROUND) Ground for ECM circuit Less than 1.0 V at all times 

ECM Inputs and Outputs at Connector No. 5 (9P)

 

NOTE: Standard battery voltage is 12 V.

ECM Terminal number Pin Box Terminal number Wire color Terminal name Description Signal 
122 RED ETC1 (ELECTRIC THROTTLE CONTROL SYSTEM 1) Drives throttle actuator With throttle valve moving: duty controlled
With throttle valve not moving: not specified 
123 GRN ETC2 (ELECTRIC THROTTLE CONTROL SYSTEM 2) Drives throttle actuator With throttle valve moving: duty controlled
With throttle valve not moving: not specified 
124 BLU/RED EGR (EXHAUST GAS RECIRCULATION (EGR) VALVE) Drives EGR valve With EGR operating: duty controlled
With EGR not operating: about 0 V 
125 BLK/WHT SO2SHTC (SECONDARY HEATED OXYGEN SENSOR (SECONDARY HO2S) HEATER CONTROL) Drives secondary HO2S heater With ignition switch ON (II): battery voltage
With fully warmed up engine running: duty controlled 
126 GRN/BLK EGRG (EXHAUST GAS RECIRCULATION (EGR) VALVE GROUND) Ground for EGR valve Less than 1.0 V at all times 
128 YEL/BLK IGP1 (POWER SOURCE) Power source for ECM circuit With the ignition switch ON (II): battery voltage
With the ignition switch OFF: about 0 V 
129 YEL/BLK IGP2 (POWER SOURCE) Power source for ECM circuit With the ignition switch ON (II): battery voltage
With the ignition switch OFF: about 0 V 
130 BLK/WHT PO2SHTC (PRIMARY HEATED OXYGEN SENSOR (PRIMARY HO2S) HEATER CONTROL) Drives primary HO2S heater With ignition switch ON (II): battery voltage
With fully warmed up engine running: duty controlled 

Vacuum Hose Routing


 

Vacuum Distribution


 

PGM-FI System


The Programmed Fuel Injection (PGM-FI) system is a sequential multiport fuel injection system.

Air Conditioning (A/C) Compressor Clutch Relay

When the Engine Control Module (ECM) receives a demand for cooling from the A/C system, it delays the compressor from being energized, and enriches the mixture to assure smooth transition to the A/C mode.

Alternator Control

The alternator signals the ECM during charging.

Barometric Pressure (BARO) Sensor

The BARO sensor is inside the ECM. It converts atmospheric pressure into a voltage signal that modifies the basic duration of the fuel injection discharge.

Camshaft Position (CMP) Sensor

The CMP sensor detects the position of the No. 1 cylinder as a reference for sequential fuel injection to each cylinder.

 

Crankshaft Position (CKP) Sensor

The CKP sensor detects engine speed and determines ignition timing and timing for fuel injection of each cylinder.

 

Engine Coolant Temperature (ECT) Sensor

The ECT sensor is a temperature dependent resistor (thermistor). The resistor of the thermistor decreases as the engine coolant temperature increases.

 

i-DSI System

The ECM controls the ignition phase gap between the front and rear spark plugs in accordance with the engine speed and the vacuum in the intake manifold.

 

Ignition Timing Control

The ECM contains the memory for basic ignition timing at various engine speeds and manifold absolute pressure. It also adjusts the timing according to engine coolant temperature.

Injector Timing and Duration

The ECM contains the memory for basic discharge duration at various engine speeds and manifold pressures. The basic discharge duration, after being read out from the memory, is further modified by signals sent from various sensors to obtain the final discharge duration.
By monitoring long term fuel trim, the ECM detects long term malfunctions in the fuel system, and will set a Diagnostic Trouble Code (DTC).

Intake Air Temperature/Manifold Absolute Pressure (IAT/MAP) Sensor

The IAT sensor is a temperature dependant resistor (thermistor). The resistance of the thermistor decreases as the intake air temperature increases.

The MAP sensor converts manifold absolute pressure into electrical signals to the ECM.

 

Knock Sensor

The knock control system adjusts the ignition timing to minimize knock.

 


Primary Heated Oxygen Sensor (Primary HO2S)

The primary HO2S detects the oxygen content in the exhaust gas and sends signals to the ECM which varies the duration of fuel injection accordingly. To stabilize its output, the sensor has an internal heater. The primary HO2S is installed in the exhaust manifold. By controlling the air fuel ratio with primary HO2S and secondary HO2S, the deterioration of the primary HO2S can be evaluated by its feedback period. When the feedback period exceeds a certain value during stable driving conditions, the sensor is considered deteriorated and the ECM sets a DTC.

 

Secondary Heated Oxygen Sensor (Secondary HO2S)

The secondary HO2S detects the oxygen content in the exhaust gas downstream of the Three Way Catalytic Converter (TWC) and sends signals to the ECM which varies the duration of fuel injection accordingly. To stabilize its output, the sensor has an internal heater. The secondary HO2S is installed in the TWC.

 

Starting Control

When the engine is started, the ECM provides a rich mixture by increasing injector duration.

Vehicle Speed Sensor (VSS)

The VSS is driven by the differential. It generates a pulsed signal from an input of 5 volts. The number of pulses per minute increases/decreases with the speed of the vehicle.

Electronic Throttle Control System


The throttle is electronically controlled by the electronic throttle control system. Refer to the System Diagram to see the functional layout of the system.

Idle control: When the engine is idling, the ECM controls the throttle actuator to maintain the proper idle speed according to engine loads.

Acceleration control: When the accelerator pedal is pressed, the ECM opens the throttle valve depending on the accelerator pedal position (APP) sensor signal.

Accelerator Pedal Position (APP) Sensor

As the accelerator pedal position changes, the sensor varies the signal voltage to the ECM.

 

Throttle Body

The throttle body is a single-barrel side draft type. The lower portion of the throttle valve is heated by engine coolant from the cylinder head to prevent icing of the throttle plate.

 

Idle Control System


When the engine is cold, the A/C compressor is on, the transmission is in gear, the brake pedal is pressed, or the alternator is charging, the ECM controls current to the throttle actuator to maintain the correct idle speed.

Brake Pedal Position Switch

The brake pedal position switch signals the ECM when the brake pedal is pressed.

Fuel Supply System


Fuel Cut-off Control

During deceleration with the throttle valve closed, current to the injectors is cut off to improve fuel economy at speeds over 1,160 rpm (min-1). Fuel cut-off action also occurs when engine speed exceeds 6,200 rpm (min-1), regardless of the position of the throttle valve, to protect the engine from over-revving. When the vehicle is stopped, the ECM cuts the fuel at engine speeds over 6,200 rpm (min-1).

Fuel Pump Control

When the ignition is turned on, the ECM grounds the PGM-FI main relay which feeds current to the fuel pump for 2 seconds to pressurize the fuel system. With the engine running, the ECM grounds the PGM-FI main relay and feeds current to the fuel pump. When the engine is not running and the ignition is on, the ECM cuts ground to the PGM-FI main relay which cuts current to the fuel pump.

PGM-FI Main Relay 1 and 2

The PGM-FI relay consists of two separate relays. The PGM-FI main relay 1 is energized whenever the ignition switch is ON (II) which supplies battery voltage to the ECM, power to the injectors, and power for the PGM-FI main relay 2. The PGM-FI main relay 2 is energized to supply power to the fuel pump for 2 seconds when the ignition switch is turned ON (II), and when the engine is running.

Catalytic Converter System


Three Way Catalytic Converter (TWC)

The TWC converts hydrocarbons (HC), carbon monoxide (CO), and oxides of nitrogen (NOx) in the exhaust gas to carbon dioxide (CO2), dinitrogen (N2), and water vapor.

 

Exhaust Gas Recirculation (EGR) System


Refer to the System Diagram to see the functional layout of the system.

EGR Valve

The EGR valve lowers peak combustion temperatures and reduces oxides of nitrogen emissions (NOx) by recirculating exhaust gas through the intake manifold and into the combustion chambers.

Positive Crankcase Ventilation (PCV) System


The PCV valve prevents blow-by gasses from escaping into the atmosphere by venting them into the intake manifold.

 

Evaporative Emission (EVAP) Control System


Refer to the System Diagram to see the functional layout of the system.

EVAP Canister

The EVAP canister temporarily stores fuel vapor from the fuel tank until it can be purged back into the engine and burned (refer to the System Diagram to see the functional layout of the system).

EVAP Canister Purge Valve

When the engine coolant temperature is below 40°C (104°F), the ECM turns off the EVAP canister purge valve which cuts vacuum to the EVAP canister.

Electronic Throttle Control System Diagram


The electronic throttle control system consists of the throttle actuator, throttle position (TP) sensor, accelator pedal position (APP) sensor, throttle actuator control module, and the ECM. The throttle is electronically controlled by this system.

 

Exhaust Gas Recirculation (EGR) System Diagram


The EGR system reduces oxides of nitrogen (NOx) emissions by recirculating exhaust gas through the EGR valve and the intake manifold into the combustion chambers. The ECM memory includes the ideal EGR valve position for varying operating conditions.

The EGR valve position sensor detects the amount of EGR valve lift and sends it to the ECM. The ECM then compares it with the ideal lift in its memory (based on signals sent from other sensors). If there is any difference between the two, the ECM cuts current to the EGR valve.

 

Evaporative Emission (EVAP) Control Diagram


The EVAP controls minimize the amount of fuel vapor escaping to the atmosphere. Vapor from the fuel tank is temporally stored in the EVAP canister until it can be purged from the EVAP canister into the engine and burned.