THROTTLE SYSTEM
Throttle is cable-operated. Engine Control Module (ECM) reads throttle position via throttle position sensor.
TURBOCHARGER
Turbocharger boost pressure is controlled by Boost Pressure Control (BPC) valve. BPC valve pressure regulator is affected by pressure from turbocharger. ECM determines current throttle angle and boost pressure to achieve calculated torque. ECM also affects controlling pressure using turbocharger control valve.
When pressure increases, BPC valve pressure regulator is affected. When boost pressure has increased to maximum permissible value, BPC valve opens and part of the exhaust gases bypass turbocharger, which limits boost pressure.
COMPUTERIZED ENGINE CONTROLS
S40 and V40 models use a Siemens fuel injection and electronic ignition system. System has complete self-diagnostic capabilities. System uses an Engine Control Module (ECM) that receives input from engine monitoring sensors. See INPUT DEVICES . ECM uses these input signals to control air/fuel mixture for emission control, fuel economy and good driveability.
ENGINE CONTROL MODULE
Engine Control Module (ECM) provides precise control of fuel, ignition and turbocharger operation. System has self-diagnostic capabilities. ECM is located behind center console, underneath dashboard. (Scheme 1)
Scheme 1
INPUT DEVICES
Note. Components are grouped into 2 categories. The first category is INPUT DEVICES , which control or produce voltage signals monitored by ECM called input signals. The second category is OUTPUT SIGNALS , which are components controlled by ECM.
Vehicles are equipped with different combinations of input devices. Not all devices may be used.
A/C Pressure Sensor
Signals ECM of A/C operation. This allows ECM to control idle speed.
Brake Light Switch
Brake light switch informs ECM that vehicle is braking.
Boost Pressure Sensor No. 1
Note. Boost pressure sensor No. 1 may also be known as charge pressure sensor No. 2. Sensor is located in air intake duct on charge air cooler.
Sensor measures pressure at the charge air cooler outlet and replaces the previous altitude sensor (2000 models). Sensor protects the turbo compressor by limiting the charging pressure when the vehicle is driven at high altitude. Sensor is a piezo-resistive type.
Boost Pressure Sensor No. 2
Note. Boost pressure sensor No. 2 may also be known as charge pressure sensor No. 1 or Manifold Absolute Pressure (MAP) sensor.
Sensor is located on intake manifold, between the intake runners.
Camshaft Position Sensor
ECM uses Camshaft Position (CMP) sensor signal to determine in which cylinder ignition is required and, if knock is detected, which cylinder is knocking.
Engine Coolant Temperature Sensor
Engine Coolant Temperature (ECT) sensor is a negative temperature coefficient type sensor, meaning its resistance lessens as temperature increases.
Engine Speed (RPM) Sensor
Edge of flywheel/carrier plate has a series of holes along its edge. As it passes RPM sensor (located on flywheel side of engine block), each hole induces a voltage in sensor coil.
Heated Oxygen Sensor
Heated Oxygen (HO2S) sensor generates an electrical signal proportional to air/fuel mixture. ECM uses this information to adjust amount of injected fuel into cylinders.
Ignition Switch +50 Supply
Signal provides early information to ECM to prepare for start.
Intake Air Temperature Sensor
Intake air temperature (IAT) sensor provides information about intake air temperature after Charge Air Cooler (CAC).
Knock Sensor
Knock Sensor (KS) detects knocking (detonation) and sends signal to ECM. ECM is able to gradually retard ignition timing to each individual cylinder. If knocking does not stop, a signal is sent to ECM to enrich air/fuel mixture.
Mass Airflow Sensor
Mass Airflow (MAF) sensor uses a hot film, rather than a heated wire to measure intake air mass. Since working temperature as high as 338°F (170°C), and flow and temperature-sensitive resistances are mounted on side of hot film, a burn-off function is not required.
Oil Pressure Switch
Oil pressure switch provides information about engine oil pressure to ECM.
OUTPUT SIGNALS
Note. Vehicles are equipped with different combinations of computer-controlled components. Not all components listed below are used. For theory and operation of each output component, refer to system indicated after component.
ECM processes information from input sensors and sends appropriate voltage control signals to control devices.
A/C Compressor Clutch
A/C compressor clutch relay is controlled by the ECM based on input from the climate control system. For circuit details, see AIR CONDITIONING wiring diagrams in SYSTEM WIRING DIAGRAMS.
A/C Condenser Fan
A/C condenser fan relay is controlled by the ECM based on input from the climate control system. For circuit details, see AIR CONDITIONING wiring diagrams in SYSTEM WIRING DIAGRAMS.
Boost Pressure Control (BPC) Valve
See TURBOCHARGER under AIR INDUCTION SYSTEM.
Canister Purge (CP) Valve
See Canister Purge (CP) Valve under EMISSION SYSTEMS.
Dynamic Stability Assistance (DSA)
The ECM works with the DSA system to control wheel spin.
Engine Cooling Fan
Electric fan relays are controlled by the ECM based on input from the Engine Coolant Temperature (ECT) sensor. For circuit details, see AIR CONDITIONING wiring diagrams in SYSTEM WIRING DIAGRAMS.
Malfunction Indicator Light
See MALFUNCTION INDICATOR LIGHT under SELF-DIAGNOSTIC SYSTEM.
Fuel Injectors
See FUEL CONTROL under FUEL SYSTEM.
Fuel Pump
See FUEL DELIVERY under FUEL SYSTEM.
Ignition Coil/Power Stage
See ELECTRONIC IGNITION under IGNITION SYSTEM.
Models are equipped with an in-tank fuel pump. Fuel pump is equipped with a check valve to hold fuel pressure in system when ignition is off. Fuel is sent through an in-line fuel filter. Fuel is then sent to fuel pressure regulator where pressure is maintained at a constant pressure in relationship to manifold pressure. Excess fuel returns to fuel tank via a return line.
FUEL CONTROL
ECM calculates base injection pulse width by processing signals from various engine sensors. Information from engine speed (RPM) sensor at flywheel is used to trigger timing of fuel injection. During normal driving conditions, injection duration is regulated in reference to MAF sensor, engine speed, oxygen content of exhaust gases and coolant temperature. Under full throttle conditions, a richer fuel mixture is provided for increased power and to reduce combustion heat in engine and catalytic converter.
Each injector incorporates a solenoid, plunger and needle valve which opens and closes an orifice. ECM supplies current through auxiliary relay for a predetermined period, opening all injectors simultaneously to inject atomized fuel. Injection takes place twice per revolution while starter motor is running and once per revolution under normal driving conditions.
IDLE SPEED
Engine idle speed is controlled by ECM depending upon engine operating conditions. ECM senses engine operating conditions and determines best idle speed. Idle speed is controlled by varying air passage inside idle air control valve.
Idle Air Control Valve
Idle Air Control (IAC) valve uses a solenoid to control by-pass air. Signal from ECM determines idle speed by controlling amount of by-pass air.
ELECTRONIC IGNITION
ECM computes correct timing of each ignition pulse in response to signals from engine speed (RPM) sensor, Camshaft Position (CMP) sensor, Mass Airflow (MAF) sensor, Engine Coolant Temperature (ECT) sensor, Throttle Position (TP) sensor, Knock Sensors (KS) and Transmission Control Module (TCM).
The S40 and V40 4-cylinder engines are equipped with two ignition coils, eliminating the distributor. ECM computes when each ignition coil must deliver its voltage pulse.
Continuous Variable Valve Timing (CVVT)
CVVT unit is mounted on exhaust camshaft. Control has 15 camshaft degrees between its outer positions. Engine uses CVVT to minimize emissions.
Ignition Timing Advance Control
Ignition timing is controlled by ECM. Ignition timing is based on preprogrammed information and modified by inputs from engine sensors.
Knock sensor is fitted to cylinder block to sense detonation inside cylinders. When detonation is detected, ECM retards ignition timing in each cylinder individually until knocking stops.
CRANKCASE VENTILATION
The crankcase ventilation system on turbocharged engines is equipped with a heater. It is a Positive Temperature Coefficient (PTC) type that is powered through the system relay. see scheme 4
FUEL EVAPORATIVE SYSTEM (EVAP)
Evaporative emissions system is designed to prevent fuel vapor from entering atmosphere. Fuel system is completely sealed and vented only through a carbon canister. System consists of pressure/vacuum relief fuel filler cap, rollover valve, charcoal canister, purge valve and various connecting hoses. Fuel pressure/vacuum relief filler cap allows excessive tank pressure to vent. It also allows air into fuel tank if vacuum should become excessive due to a malfunction in fuel evaporation system. Fuel tank vapor is vented by a line through rollover valve to charcoal canister. Rollover valve is located in vent line close to fuel tank. Valve is designed to prevent fuel spillage if vehicle rolls over. Valve is open until vehicle is at a 45-degree angle or more from horizontal position.
Charcoal canister is filled with activated charcoal. Fuel vapor from tank is absorbed by charcoal when engine is not running. When engine is running faster than idle, canister purge valve opens and fuel vapor is drawn into engine and burned. (Scheme 2)
Scheme 2
All models are equipped with a CHECK ENGINE Malfunction Indicator Light (MIL) located on instrument panel. Light will illuminate when ignition switch is turned to ON position (bulb check) or when emission-related systems are malfunctioning during normal engine operation.