Mitsubishi Montero (1998+). Manual - part 115

 

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Mitsubishi Montero (1998+). Manual - part 115

 

 

         HO2S detects oxygen content in exhaust gas and sends this

information to PCM. PCM uses input signals from HO2S to vary duration

of fuel injection. HO2S heater stabilizes sensor temperature

regardless of exhaust gas temperature to allow for more accurate

exhaust oxygen content readings.

         Idle Air Control (IAC) Valve Position Sensor

         Sensor is incorporated in IAC motor. Sensor senses IAC motor

plunger position and sends electrical signal to PCM.

         Ignition Timing Adjustment Terminal

         Used for adjusting base ignition timing. When terminal is

grounded, PCM timing control function is by-passed, allowing base

timing to be adjusted.

         Intake Air Temperature (IAT) Sensor

         IAT sensor is incorporated into airflow sensor assembly. This

resistor-based sensor measures temperature of incoming air and

supplies air density information to PCM.

         Knock Sensor (KS)

         KS is located in cylinder block and senses engine vibration

during detonation (knock). KS converts vibration into electrical

signal. PCM retards ignition timing based on this signal.

         Manifold Differential Pressure (MDP) Sensor

         MDP sensor converts negative air pressure in intake manifold

plenum into voltage signals sent to PCM. PCM monitors Exhaust Gas

Recirculation (EGR) system using these signals.

         Park/Neutral Position (PNP) Switch (Automatic Transmission)

         PNP switch senses position of transmission select lever,

indicating engine load due to automatic transmission engagement. Based

on this signal, PCM commands IAC motor to increase throttle angle,

maintaining optimum idle speed.

         Power Steering Oil Pressure Switch

         Switch detects increase in power steering oil pressure. When

power steering oil pressure increases, switch contacts close,

signaling PCM. PCM commands IAC motor, raising idle speed to

compensate for drop in engine RPM due to power steering load.

         Throttle Position (TP) Sensor

         TP sensor is a variable resistor mounted on throttle body.

PCM uses voltage signal from TP sensor to determine throttle plate

angle.

         Vehicle Speed Sensor (VSS)

         Mounted on transaxle/transmission, VSS sends a pulsing signal

to PCM for vehicle speed calculation. PCM uses this calculation for

cruise control and fuel cut-off.

         Volume Airflow (VAF) Sensor

         Incorporated into airflow sensor assembly, VAF sensor

measures intake airflow rate. Intake air flows through tunnel in

airflow sensor assembly. VAF sensor sends frequency signal to PCM. PCM

uses signal to adjust fuel injection rate.

         OUTPUT SIGNALS

NOTE:    Vehicles are equipped with various combinations of

         computer-controlled components. Not all components listed

         below are used on every vehicle. To determine component

         usage on specific models, see appropriate wiring diagram in

         L - WIRING DIAGRAMS article. For theory and operation on each

         output component, refer to system indicated after component.

         Data Link Connector (DLC)

         See SELF-DIAGNOSTIC SYSTEM.

         EGR Control Solenoid Valve

         See EXHAUST GAS RECIRCULATION (EGR) CONTROL under EMISSION

SYSTEMS.

         Fuel Injectors

         See FUEL CONTROL under FUEL SYSTEM.

         Fuel Pressure Control Solenoid Valve (Turbo)

         See FUEL DELIVERY under FUEL SYSTEM.

         Fuel Pressure Regulator

         See FUEL DELIVERY under FUEL SYSTEM.

         Idle Air Control (IAC) Motor

         See IDLE SPEED under FUEL SYSTEM.

         Malfunction Indicator Light

         See SELF-DIAGNOSTIC SYSTEM.

         Power Transistor(s) & Ignition Coils

         See IGNITION SYSTEMS.

         Purge Control Solenoid Valve

         See EVAPORATIVE CONTROL under EMISSION SYSTEMS.

         Wastegate Control Solenoid Valve

         See TURBOCHARGED ENGINES under AIR INDUCTION SYSTEM.

         FUEL SYSTEM

         FUEL DELIVERY

         Electric fuel pump, located in gas tank, feeds fuel through

in-tank fuel filter, external fuel filter (located in engine

compartment) and fuel injector rail.

         Fuel Pump

         Fuel pump consists of a motor-driven impeller. Pump has an

internal check valve to maintain system pressure, and a relief valve

to protect fuel pressure circuit. Pump receives voltage supply from

MFI control relay.

         Fuel Pressure Control Solenoid Valve (Turbo)

         Valve prevents rough idle due to fuel percolation. On engine

restart, if engine coolant or intake air temperature reaches a preset

value, PCM applies voltage to fuel pressure control solenoid valve for

2 minutes after enginerestart. Valve will open, allowing atmospheric

pressure to be applied to fuel pressure regulator diaphragm. This

allows maximum available fuel pressure at injectors, enriching fuel

mixture and maintaining stable idle at high engine temperatures.

         Fuel Pressure Regulator

         Located on fuel injector rail, this diaphragm-operated relief

valve adjusts fuel pressure according to engine manifold vacuum.

         As engine manifold vacuum increases (closed throttle), fuel

pressure regulator diaphragm opens relief valve, allowing pressure to

bleed off through fuel return line, reducing fuel pressure.

         As engine manifold vacuum decreases (open throttle), fuel

pressure regulator diaphragm closes valve, preventing pressure from

bleeding off through fuel return line, increasing fuel pressure.

         FUEL CONTROL

         Fuel Injectors

         Fuel is supplied to engine through electronically pulsed

(timed) injector valves located on fuel rail(s). PCM controls amount

of fuel metered through injectors based on information received from

sensors.

         IDLE SPEED

         Air Conditioning (A/C) Relay

         When A/C is turned on with engine at idle, PCM signals IAC

motor to increase idle speed. To prevent A/C compressor from switching

on before idle speed has increased, PCM momentarily opens A/C relay

circuit.

         Idle Air Control (IAC) Motor

         Motor controls pintle-type air valve to regulate volume of

intake air at idle.

         During start mode, PCM controls idle intake air volume

according to Engine Coolant Temperature (ECT) sensor input. After

starting, with idle position switch activated (throttle closed), fast

idle speed is controlled by IAC motor and fast idle air control valve

(if equipped).

         When idle switch is deactivated (throttle open), IAC motor

moves to a preset position in accordance with ECT sensor input.

         PCM signals IAC motor to increase engine RPM in the following

situations: A/T (if applicable) is shifted from Neutral to Drive, A/C

is turned on, or power steering pressure reaches a preset value.

         IGNITION SYSTEMS

         DIRECT IGNITION SYSTEM (DIS)

         Depending on number of cylinders, ignition system is a 2 or

3-coil, distributorless ignition system. On Eclipse (Turbo) and DOHC

V6 engines, Camshaft Position (CMP) sensor is located beside camshaft,

in front of engine. On all other engines equipped with DIS, CMP sensor

is a separate unit mounted in place of distributor. On DOHC 4-

cylinder, DOHC V6 and 1.8L 4-cylinder engines with California

emissions, Crankshaft Position (CKP) sensor is located beside

crankshaft, in front of engine. PCM determines TDC based on pulse

signals received from sensors and then controls MFI and ignition

timing.

         Power Transistors & Ignition Coils

         Based on crankshaft position and CMP sensor inputs, PCM

controls timing and directly activates each power transistor to fire

coils. On 4-cylinder engines, power transistor "A" controls primary

current of ignition coil "A" to fire spark plugs on cylinders No. 1

and No. 4 at the same time. Power transistor "B" controls primary

current of ignition coil "B" to fire spark plugs on cylinders No. 2

and No. 3 at the same time. On V6 engines, companion cylinders No. 1

and 4, 2 and 5, and 3 and 6 are fired together.

         On all models, although each coil fires 2 plugs at the same

time, ignition takes place in only one cylinder, since the other

cylinder is on its exhaust stroke when plug fires.

         HALL EFFECT IGNITION SYSTEM

         This system is equipped with a Hall Effect distributor.

Shutter(s) attached to distributor shaft rotate through distributor

Hall Effect switch, also referred to as a Camshaft Position (CMP)

sensor, which contains a distributor pick-up (a Hall Effect device and

magnet). As shutter blade(s) pass through pick-up, magnetic field is

interrupted and voltage is toggled between high and low. PCM uses this

data along with Crankshaft Position (CKP) sensor data to control

ignition timing and injector pulse width to maintain optimum

driveability.

         Power Transistor & Ignition Coil

         Power transistor is mounted inside distributor with disc and

optical sensing unit. When ignition is on, ignition coil primary

circuit is energized. As distributor shaft rotates, disc rotates,

triggering optical sensing unit. PCM receives signals from optical

sensing unit. Signals are converted and sent to power transistor,

interrupting primary current flow and inducing secondary voltage.

         IGNITION TIMING CONTROL SYSTEM

         Ignition timing is controlled by PCM. PCM adjusts timing

based on various conditions such as engine temperature, altitude and

detonation.

         EMISSION SYSTEMS

         EXHAUST GAS RECIRCULATION (EGR) CONTROL

         Federal Emissions (Non-Turbo)

         To lower oxides of nitrogen (NOx) exhaust emissions, a non-

computer controlled exhaust gas recirculation system is used. EGR

operation is controlled by throttle body ported vacuum. Vacuum is

routed through vacuum control valve to prevent EGR operation at low

engine temperatures.

         Spring pressure holds EGR valve closed during low vacuum

conditions (engine idling or wide open throttle). When vacuum pressure

increases and overcomes EGR spring pressure, EGR valve is lifted to

allow exhaust gases to flow into intake manifold for combustion.

         California Emissions & Turbo

         PCM controls EGR operation by activating EGR control solenoid

valve according to engine load. When engine is cold, PCM signals EGR

control solenoid valve to deactivate EGR.

         EGR Control Solenoid Valve

         Valve denies or allows vacuum supply to EGR valve based on

PCM commands.

         EVAPORATIVE CONTROL

         Fuel evaporation system prevents fuel vapor from entering

atmosphere. System consists of special fuel tank with vapor separator

tanks (if equipped), vacuum relief filler cap, overfill limiter (2-way

valve), fuel check valve, thermovalve (if equipped), charcoal

canister, purge control valve, purge control solenoid valve, and

connecting lines and hoses.

         Purge Control Solenoid Valve

 

 

 

 

 

 

 

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