Identification: system components Peugeot Expert I

Computer

Using the data which it receives from the various sensors, the ECU carries out the following functions

• Calculates the advance and controls the static ignition
• Calculates the injection time and controls the injectors

The ECU also controls auxiliary data, in particular

• Regulation of idle speed
• The coil charge time regulation
• The fuel pump control, via a double relay
• Recycling of fuel vapours
• Rev counter and consumption data
• Reading of faults and operation of emergency mode
• The actuator test
• Cut-off during over-run
• The diagnostics light control
• Air conditioning engagement authorisation
• Knock detection
• Purge canister

Engine speed and position sensor

The engine speed and position sensor is secured to the clutch housing opposite the engine flywheel identification; it comprises a magnetic core surrounded by a coil

This sensor supplies the engine rotation speed and defines the crankshaft position on a 60 tooth wheel, 2 teeth of which have been removed to identify TDC (no. 1-5 cylinder)

Inlet pressure sensor

This sensor supplies load data by measuring the pressure of the air admitted downstream of the throttle housing; it is integral with the inlet pipes

Supplied with 5 V by the ECU, this sensor returns a voltage proportional to the pressure measured

Micromechanical type sensor

Throttle solenoid valve

The potentiometer supplies the position of the throttle to the ECU

This data is used for recognition of the Foot Off, Foot Fully On and Intermediate positions for the acceleration, deceleration and injection cut-off procedures

Supplied with 5 V by the ECU, this potentiometer returns a voltage to the ECU which varies in relation to the position of the throttle

This potentiometer also operates in emergency mode should an inlet pressure sensor fault occur; it cannot be adjusted

Engine temperature sensor

This sensor supplies the thermal condition of the engine to the ECU by measuring the coolant temperature

The electrical resistance of this NTC (Negative Temperature Coefficient) sensor decreases as the temperature increases

Air temperature sensor

Positioned at the air filter outlet, this sensor sends intake air temperature data to the ECU

The electric resistor is of the CTN type (negative temperature coefficient)

Vehicle speed sensor

Induction type sensor linked to a vehicle speed interface unit

This sensor generates a square signal whose frequency is proportional to the vehicle speed, amplified and transformed by the interface unit

Oxygen sensor

This sensor is fitted on the exhaust, at the catalytic converter inlet, and it continuously supplies the ECU with a voltage which corresponds to the oxygen content of the exhaust gas

This voltage, when analysed by the ECU, allows the injection time to be corrected

Rich mixture: sensor voltage ≃ 0,8 V

Lean mixture: sensor voltage ≃ 0,1 V

An internal heating device allows the sensor to reach its operating temperature quickly, greater than 350 °C

Catalytic converter

The catalytic converter is designed to reduce by catalysis the pollutant gases burned in the exhaust

• CO: carbon monoxides
• HC: hydrocarbons
• NOx: nitrous oxides

Catalysis is a phenomenon which, via the intermediary of a catalyst, speeds up chemical reactions without combustion or modification of the catalyst itself

Treating the three principal pollutants, the catalytic converter is of the three function type (3 way)

Composition of the catalytic converter: a stainless steel envelope, a heat insulator and a honeycomb ceramic block

The ideal temperature for efficient purification is between 600 and 800 °C, however, too high a temperature, over 1000 degrees C, may destroy the catalytic converter

This temperature is determined by the richness of the mixture, which is why very precise mixture control is necessary to prevent damage to the catalytic converter

Double relay

2 double relay

1 - main supply (1304)

• Computer battery +
• Fuel pump
• Butterfly housing heating
• Idle speed regulation solenoid
• Canister discharge electrovalve
• Injectors
• Power relay (oxygen sensor heating stage)

2 - power (1307)

• Ignition system
• Oxygen sensor heater
• Computer ignition controlled +
• Coded anti-start

Ignition coil

The ignition is of the twin-static type

The coil is triple, it has three primary circuits and three distict secondary circuits

The high tension rotor and distributor assembly is no longer present

Each secondary outlet is connected to a plug, directly for the front rail and via a wire for the rear rail

Injectors

The injection is semi-sequential

The injectors are of the electromagnetically controlled type

The injectors are integral with the supply rail and are supplied from the side

The electrical impulses originating from the injection ECU create a magnetic field in the electromagnet coil, the core is attracted and the injector needle is lifted from its seat

The pressurised fuel is sprayed upstream of the valve seat

Idle speed regulation solenoid

The idle regulation solenoid valve allows control of the idle speed

This solenoid valve consists of a rotary valve which allows the passage of a greater or lesser quantity of air, this is controlled by a rotor with two windings with opposite effects; it is fitted head downwards

Canister discharge electrovalve

Controlled by the ECU, the purge canister solenoid valve allows the fuel vapours in the canister reservoir to be recirculated in accordance with the engine operating conditions

The valve is in the closed condition when it is not supplied (NF)

Normally closed solenoid valve: (brown connector with fool-proof identification)

Canister reservoir

The canister reservoir is a storage container, filled with activated carbon

The activated carbon attracts the fuel vapours from the tank, traps them, to prevent them evaporating into the atmosphere until they are drawn into the engine

The fuel vapour recirculation phases are governed by the ECU which controls the purge canister solenoid valve

Fuel pump

The fuel pump is immersed in the fuel tank and is of the BOSCH EKP 10 type

Fuel filter

The filter is installed on the fuel supply line

Filtration threshold: 8 to 10 μ

Pressure regulator

Positioned at the end of the supply rail, this pressure regulator maintains an average pressure of 3 bars at the injector terminals between upstream and downstream, with the vacuum pipe disconnected

Knock sensor

The knock sensor, of the piezo-electric type, is fitted to the engine block

This sensor allows the detection of knocking, a vibration caused by explosive inflammation of the mixture in the combustion chamber

If this phenomenon is repeated it may result in damage to mechanical parts caused by an abnormal increase in the temperature

Throttle butterfly housing

Fitted with a single butterfly, the throttle housing contains the butterfly position potentiometer and the heating resistor

Throttle butterfly housing heating element

The heating resistor is of the CTP type (Positive Temperature Coefficient); secured to the throttle housing, its purpose is to prevent the formation of ice

Injection-ignition warning lamp

This function warns the driver if a fault is detected by the ECU

Lighting of the warning lamp when the ignition is switched on:

Two cases are possible

• Normal operation: the warning light remains on until the engine is started
• Major fault: if a major fault has been stored in the memory during the last operation of the engine, the warning lamp will remain lit for 5 seconds on starting when the engine is running, the light comes on every time a major fault is detected, and remains lit as long as the fault has not disappeared