AIR INDUCTION SYSTEM
All engines use the same basic air induction system. Remote air cleaner (with intake air temperature sensor) routes air through MAF sensor to plenum-mounted throttle body.
COMPUTERIZED ENGINE CONTROLS
All engines use Sequential Multiport Fuel Injection (SFI) and Distributorless Ignition System (DIS) controlled by Engine Control Module (ECM). Input devices supply ECM with signals which indicate operating conditions of the vehicle. ECM output signals control systems which control vehicle operation to optimize emission control and vehicle performance. On vehicles equipped with automatic transmission/transaxles, ECM also sends outputs to, and receives inputs from, Transmission Control Module (TCM).
ENGINE CONTROL MODULE (ECM)
The Engine Control Module (ECM), through various input sensors, monitors cranking signal, intake air amount, intake air temperature, air/fuel ratio, throttle valve opening angle, No. 1 piston compression stroke TDC, engine coolant temperature, engine RPM, vertical chassis movement, A/C operation, detonation, gear status (if automatic transmission/transaxle) and fuel tank pressure. ECM uses this information to control fuel injection timing and duration, ignition timing, idle speed, A/C cutout, fuel pump, purge control system and perform self-diagnostic functions.
ECM includes On Board Diagnostics-II (OBD-II) to monitor efficiency of emissions related components and systems. If an emissions related system malfunctions or deteriorates below preprogrammed performance criteria, OBD-II will illuminate the Malfunction Indicator Light (MIL) and store a Diagnostic Trouble Code (DTC). If a condition exists that may cause catalytic converter damage, MIL will flash continuously.
Note. Components are grouped into 2 categories. The first category covers INPUT DEVICES , which produce voltage signals monitored by ECM. The second category covers OUTPUT SIGNALS , which are components controlled by ECM.
INPUT DEVICES
The ECM controls various output devices based upon signals received from input devices. These devices include sensors, switches, and circuits (such as an RPM reference signal from the ignition coil). Vehicles are equipped with different combinations of input devices. Not all devices are used on all models. To determine input usage on a specific model, see WIRING DIAGRAMS article. Available input signals include the following
A/C Switch
When the air conditioner switch is turned on, a signal is sent to the ECM that a request for A/C has been made. Location instrument panel. See A/C RELAYS under OUTPUT SIGNALS.
Camshaft Position (CMP) Sensor
CMP sensor detects No. 1 piston at TDC of compression stroke. ECM uses input for fuel and ignition control. On Optima & Magentis (Canadian) (2.5L), sensor is located rear of right cylinder head. All others are located rear of head.
Chassis Acceleration Sensor (CAS)
Detects vertical chassis movement on rough terrain. ECM uses signal for engine misfire detection determination. On Sephia and Spectra, CAS is located right side of engine compartment near shock tower. On Sportage, CAS is located at lower right engine compartment below starter.
Crankshaft Position (CKP) Sensor
CKP sensor detects crankshaft angle. ECM uses input to determine engine speed, misfire detection, and for fuel and ignition control. On Optima & Magentis (Canadian) and Rio sensor located near rear of engine. Sephia and Spectra in bell housing. Sportage is located on left side of transaxle or transmission flywheel housing.
Engine Coolant Temperature (ECT) Sensor
ECT sensor is a thermistor whose resistance decreases as engine coolant temperature increases. ECM uses ECT sensor information for controlling fuel enrichment when engine is cold. Engine Coolant Temperature (ECT) sensor is located near thermostat housing.
Fuel Tank Pressure Sensor (FTPS)
FTP sensor is a pressure-sensitive variable resistor. It measures fuel tank pressure changes, monitoring fuel tank for leaks. It is used to close the evaporative system, and observes tank pressure respectively with canister close valve. Located on fuel tank.
Heated Oxygen Sensors (HO2S)
The front HO2S determines whether the air fuel mixture is too rich or too lean. It generates a voltage signal depending on oxygen content of exhaust gases. ECM uses inputs from front HO2S for calculating fuel mixture correction to fuel injector pulse width. Located in exhaust manifold(s). ECM uses input from rear HO2S to monitor effectiveness of Three Way Catalytic (TWC) converter. Located downstream from TWC converter.
Intake Air Temperature (IAT) Sensor
IAT is thermistor whose resistance decreases as intake air temperature increases. ECM uses IAT sensor signal to control fuel delivery. When air temperature is cold, ECM enriches fuel mixture by increasing injector pulse width. ECM will decrease injector pulse width when air temperature is warm. On Optima & Magentis (Canadian) (2.5L) and Rio sensor is located in intake plenum. On Optima & Magentis (Canadian) (2.4L) sensor is a component of MAF sensor. On Sephia, Spectra and Sportage, sensor is located in air cleaner housing.
Knock Sensor (KS)
Knock sensor is mounted on engine block. Sensor detects detonation in cylinders and vibration from the engine. KS is a piezo electric element that converts vibration into a voltage signal which is then sent to ECM. ECM will retard timing based on this signal. Optima & Magentis (Canadian) (2.5L) is equipped with two KS, one located on each side of the block. On Optima & Magentis (Canadian) (2.4L), KS is located on left side of engine block. On Rio, KS is located on right side of engine block. On Sephia and Spectra, KS is located behind intake manifold support bracket. On Sportage, KS is located on right side of engine, above oil filter.
Mass Airflow (MAF) Sensor
Hot film type sensor. MAF sensor measures amount of air entering the engine. This measurement of airflow is a reflection of engine load (throttle opening). Main input used in fuel injector duration calculation. Located on air intake hose near air cleaner housing.
Manifold Absolute Pressure (MAP) Sensor (Optima & Magentis (Canadian) 2.4L)
Manifold absolute pressure sensor converts intake manifold pressure into a voltage signal. ECM uses MAP sensor signal to verify operation of Exhaust Gas Recirculation (EGR) system. Located on intake plenum.
Power Steering Pressure (PSP) Switch
The PSP switch closes in response to an increase in power steering fluid pressure (load condition). With the switch closed, a monitored voltage circuit supplied by the ECM is pulled low to vehicle ground through switch. The ECM then sends a signal to the ISC actuator to adjust idle speed to compensate for increased engine load. On Optima & Magentis (Canadian) and Rio, located on power steering pump.
Throttle Position (TP) Sensor
Throttle Position sensor resistance increases linearly as throttle is opened. Sends a voltage signal to ECM (throttle angle signal). ECM uses this signal to calculate fuel injection duration. Located on throttle body.
Transaxle/Transmission Range Switch (A/T)
Signals shift lever position to ECM. Input used by ECM for idle speed control and load/no load determination. On all vehicles except Sportage, located on left top side of transaxle. On Sportage 2WD, located on right side of transmission. On Sportage 4WD, located on left side of transferrers.
Vehicle Speed Sensor (VSS)
VSS is located within the speedometer assembly and uses a reed switch to sense speedometer gear revolutions from the transaxle. VSS converts transaxle gear revolutions into pulse signals which are sent to the ECM. On all vehicles except Sportage, sensor is located on transaxle. On Sportage 2WD, located on right side of transmission. On Sportage 4WD, located on left rear side of transferrers.
OUTPUT SIGNALS
Note. Not all components listed are used on every vehicle.
The ECM processes information from input sensors and sends appropriate voltage control signals to the following engine controls
A/C Relays
When the air conditioner switch is turned on, a signal is sent to the ECM. The ECM then adjusts the Idle Air Control (IAC) servo to maintain optimum idle speed. Appropriate voltage control signals are sent to various relays. Then allowing the A/C compressor clutch to engage. See appropriate A/C - HEATER SYSTEMS article.
Canister Close Valve (CCV)
Closes air inlet to Evaporative Emissions (EVAP) canister when ignition is turned off. Opened and closed by ECM to test EVAP system for leaks. Located near EVAP canister. See FUEL EVAPORATION SYSTEM under EMISSION SYSTEMS.
EGR Control Solenoid Valve
When actuated by ECM allows engine vacuum to reach EGR valve. Allowing exhaust gases to enter into intake manifold. Located near dynamic chamber (plenum). See EXHAUST GAS RECIRCULATION (EGR) CONTROL under EMISSION SYSTEMS.
EGI Main Relay
Normally open. Controlled by ECM. Supplies battery voltage to electrical devices. On Optima & Magentis (Canadian) relay is located right side of dash center console. On all others in main relay/fuse box in engine compartment. See SYSTEM & COMPONENT TESTING article.
Fuel Injectors
Fuel is supplied to engine through electronically pulsed injectors. ECM controls amount of fuel by controlling duration of fuel injector pulse. See SYSTEM & COMPONENT TESTING article.
Fuel Pump Relay
Normally open. Controlled by ECM. On Optima & Magentis (Canadian) relay is located right side of dash center console. On all others in main relay/fuse box in engine compartment. See SYSTEM & COMPONENT TESTING article.
Ignition Control Module
Integrated into ECM, controls operation of ignition coils. The ECM controls ignition timing, based on signals from various engine sensors.
Leak Detection Pump (Sephia & Spectra)
Valve is opened and closed by ECM command to test EVAP system for leaks. LDP is now heated and can completely eliminate the humidity factor when in test mode. Located near EVAP canister. Leak Detection Pump can be identified by a 4 pin connector terminal. Located rear of vehicle near fuel tank. See FUEL EVAPORATION SYSTEM under EMISSION SYSTEMS.
Malfunction Indicator Light (MIL)
Also called CHECK ENGINE light. Warns of problem in emission system. See SELF-DIAGNOSTIC SYSTEM .
Purge Solenoid Valve (PSV)
When actuated by ECM allows fuel vapors to be purged from EVAP canister into intake manifold. Located near dynamic chamber (plenum). See FUEL EVAPORATION SYSTEM under EMISSION SYSTEMS.
FUEL DELIVERY - RETURNLESS SYSTEM (SEPHIA & SPECTRA 1.8L)
Extra fuel is returned to fuel tank after passing through fuel filter located under car. Conventional system returns fuel after passing through fuel rail and pressure regulator. Eliminating fuel return from engine lowers fuel and fuel tank temperatures reducing evaporative emissions.
Fuel Delivery Module
Fuel delivery module consists of electric fuel pump, pressure regulator, fuel filter and fuel sender unit. Fuel delivery module is located in fuel tank.
Fuel Pressure Regulator
Fuel pressure regulator is pre-set. Modulates system pressure at return line to fuel pump. Located on fuel pump.
Fuel Pump
Fuel pump is electric pump controlled by ECM. One-way check valve maintains pressure when fuel pump is off. Located in fuel delivery module in fuel tank.
FUEL DELIVERY - CONVENTIONAL SYSTEM
Fuel is pumped from fuel tank mounted fuel pump through fuel rail to fuel injectors. Variable pressure regulator is mounted on fuel rail to control injector fuel pressure to about 40.5 psi (290 kPa) above manifold absolute pressure. Excess fuel is returned from fuel rail to fuel tank. System minimizes vapor lock by keeping fuel moving through fuel rail.
Electronic pump controlled by ECM through fuel pump relay. Control valve in fuel pump retains fuel pressure when pump is not running. Located in fuel tank as part of fuel pump assembly.
Fuel pressure regulator is a sealed unit, divided into 2 chambers (fuel and spring chambers) by a diaphragm. The fuel chamber receives fuel through fuel rail. Spring chamber is connected to intake manifold vacuum. The balance between calibrated spring pressure seating diaphragm against return pipe and vacuum pulling diaphragm away from return pipe, maintains injector fuel pressure at 40.5 psi (290 kPa) more than manifold absolute pressure. Located on end of fuel rail.
Idle Air Control (IAC) Valve
IAC solenoid is an electromechanical valve controlled by ECM. The IAC valve is mounted on intake manifold plenum and allows air to by-pass the throttle plate. The amount of air allowed to by-pass the throttle plate is controlled by a duty signal determined by ECM. Located on throttle body. See SYSTEM & COMPONENT TESTING article.
DISTRIBUTORLESS IGNITION SYSTEM (DIS)
DIS system consists of a Crankshaft Position (CKP) sensor, Camshaft Position (CMP) sensor and 2 coils. CKP sensor is located on transaxle/transmission case near flywheel. CMP sensor is located in rear of head. On 4 cylinder engines coils are located directly on top of No. 2 and No. 4 spark plugs. On V6 coil pack is mounted on rear of cylinder head. Each coil is connected to companion cylinder spark plug by plug wire. System uses waste spark method. Each coil fires 2 spark plugs simultaneously. Sensors signal ECM which cylinder is ready to fire. The ECM then triggers appropriate coil.
EMISSION SYSTEMS
CO, HC and NOx emissions are controlled by Exhaust Gas Recirculation (EGR) control system, Positive Crankcase Ventilation (PCV) system, Evaporative Emissions (EVAP) control system and catalytic converters.
Optima & Magentis (Canadian) 2.4L
ECM controls EGR operation by activating EGR control solenoid valve according to engine load. When engine is cold, ECM signals EGR control solenoid valve to deactivate EGR. ECM verifies EGR operation by monitoring the Manifold Absolute Pressure (MAP) sensor signal for a change in pressure when EGR is requested. EGR flow will result in a change in the MAP sensor signal. If signal does not change as expected, ECM will recognize this as an EGR malfunction, and will store a trouble code and turn on the Malfunction Indicator Light (MIL). See appropriate SELF DIAGNOSTICS article.
FUEL EVAPORATION SYSTEM
Note. Not all components listed are used on every vehicle. See VACUUM DIAGRAMS article.
Fuel evaporation system prevents escape of raw fuel vapor to atmosphere. System components include fuel tank, EVAP canister, Canister Close Valve (CCV), Leak Detection Pump (LDP with Heater), Purge Solenoid Valve (PSV), Fuel Tank Pressure Sensor (FTPS), rollover valve, On-board Refueling Vapor Recovery (ORVR) valve, catch tank, check valve, vapor separator, leak detection pump (Sephia/Spectra), fuel filler cap and Engine Control Module (ECM). ECM controls operation of PSV and CCV. PSV controls when fuel vapors are allowed to be drawn from EVAP canister into intake manifold so that they may be burned. CCV controls EVAP canister's vent to atmosphere.
ECM's On Board Diagnostics-II (OBD-II) runs monitors for large and small EVAP system leaks when vehicle is idling at a stop. ECM uses FTPS output to determine EVAP system pressure and pressure changes. At beginning of monitor, PSV is closed and CCV or LDP is commanded closed by ECM to measure compensation gradient. Compensation gradient is the increase in fuel tank pressure due to evaporation of fuel in fuel tank. After predetermined amount of time passes, CCV is opened and PSV is turned on. When PSV reaches 100 percent duty cycle, CCV is closed. If vacuum buildup, minus compensation gradient, is less than programmed threshold, gross leak is diagnosed. After maximum vacuum buildup, PSV is turned off (closed). If vacuum in fuel tank, minus compensation gradient, decreases to less than programmed threshold, small leak is diagnosed. CCV is opened and monitor is complete. If either gross leak, or small leak, is detected for 2 driving cycles, ECM assumes there is defect in evaporative emissions system and illuminates MIL. For EVAP codes or DTC P1446, P1447 and P1448, see appropriate SELF-DIAGNOSTICS article.
PSV is normally closed, duty cycle-controlled valve located in vapor line between EVAP canister and intake manifold. When commanded open by ECM, fuel vapors collected in EVAP canister are allowed to be drawn into (purged) intake system.
Measures pressure and vacuum levels in fuel tank. ECM can check PSV operation and for leaks in EVAP system by monitoring fuel tank pressure data during different operating cycles. Located on top of fuel pump assembly.
POSITIVE CRANKCASE VENTILATION (PCV)
The PCV system uses intake manifold vacuum to eliminate crankcase pressure and recycle blow-by gasses. Manifold vacuum draws gases from crankcase, through PCV hose, into combustion chamber. The PCV valve is positioned in hose through which crankcase gases flow on their way to combustion chamber.
By opening and closing in direct relation to engine vacuum, the PCV valve meters crankcase gas flow to combustion chamber. During periods of high manifold vacuum, such as at idle and deceleration, valve is almost completely closed, limiting flow of gases. During cruise speeds, valve permits greatest flow of gases.
Under conditions in which excessively high amounts of crankcase pressure is produced (such as heavy load), system allows excess gases to flow back through crankcase vent hose and into intake tract. See SYSTEM & COMPONENT TESTING article.
Note. Loose fuel cap will cause MIL to illuminate.
Also called CHECK ENGINE light, MIL comes on when ignition is turned on. MIL remains on for several seconds after engine has started, then goes out. If ECM detects emission related component or systems deterioration or failure, MIL will illuminate and Diagnostic Trouble Code (DTC) is stored in memory. MIL will stay on until DTC is erased with scan tool or battery is disconnected for at least 20 seconds. If detected failure may cause catalytic converter damage, MIL will continuously flash on and off. See appropriate SELF-DIAGNOSTICS article.