Flow chart
(1) inlet manifold pressure sensor
(2) crankcase breather system
(3) throttle housing heating element, on EW engine (only)
(4) motorised throttle housing
(4a) electric motor (motorised butterfly unit)
(4b) throttle position sensor (motorised butterfly unit)
(5) air filter unit
(6) air temperature sensor, on EW engine (only)
(7) air inlet manifold
(8) petrol injectors (x4)
(9) petrol injector supply rail
(10) petrol vapour recycling circuit (CANISTER)
Inlet manifold pressure sensor (1312)
Application: EW engine
Role
The sensor enables to determinate the air pressure in the intake pipe
The pressure measuring in the inlet pipe enables the microprocessor to define the amount of air entering the engine in order to meter the amount of petrol
NoteThe density of the air decreases according to the altitude
Description
"a": air entry
The pressure sensor supplies a voltage proportional to the air pressure in the inlet manifold
Electrical special features
Allocation of channels of connector
- Terminal 1: 5 Volts
- Terminal 2: earth
- Terminal 3: signal
Pressure of 1 bar = output voltage of 4,5 volts
Location
In the lower part of the inlet manifold
Motorised throttle housing (1262)
Role
Dose the quantity of air admitted in the cylinders
The request to open the air regulating flap is no longer a direct command by cable linked to the accelerator pedal
An accelerator pedal sensor informs the injection ECU of the driver's request
The injection ECU then commands the butterfly housing motor
A potentiometer incorporated in the throttle housing allows the injection computer to determine the exact position of the air regulating flap
Description
A - position of the gas butterfly, engine idling
B - position of the gas butterfly at its mechanical stop (cutting of the supply to the motorised butterfly unit)
(11) air temperature sensor (EW engine only)
(12) throttle butterfly
(13) throttle housing heating element (EW engine only)
(14) spring
"b" Stop (downgraded mode)
"c" Stop (butterfly closed)
"d" air inlet port
Immediately the ignition is switched on, the gas butterfly leaves its mechanical stop (see A)
Engine idling, the gas butterfly moves so as to supply the necessary air flow to the engine (replaces the idling regulator stepper motor)
Emergency mode if electrical supply to the butterfly unit is cut off
- A return spring brings the butterfly back to its stop as "b" (see B)
- The openings "d" allow sufficient air flow for driving at low speeds
The position of the throttle is monitored by the injection ECU (potentiometer incorporated in the butterfly unit)
The injection ECU cuts off the supply to the throttle housing if certain faults are present
The complete closing of the butterfly requires the compression of the spring (14)
WarningDo not attempt to adjust or dismantle a butterfly unit (safety)
Electrical special features
Control: injection ECU
Variable voltage control (OCR)
- Opening of the throttle: positive OCR voltage
- Closing of the throttle: negative OCR voltage
NoteOCR: opening cyclic ratio
The throttle housing is closed by a return spring
Should the butterfly become fouled, the injection ECU supplies the butterfly motor with a negative voltage
Allocation of channels of connector
- Terminal 1: 5 volts supply
- Terminal 2: throttle position signal 1
- Terminal 3: (+) engine
- Terminal 4: (-) engine
- Terminal 5: earth (potentiometer)
- Terminal 6: throttle position signal 2
Throttle open fully open
- Voltage between earth and track 2: 4,45 to 4,95 Volts
- Voltage between earth and track 6: 0,05 to 0,55 Volts
Throttle closed closed position
- Voltage between earth and track 2: 0,3 to 0,7 Volts
- Voltage between earth and track 6: 4,3 to 4,7 Volts
Position of the throttle back-up mode
- Voltage between earth and track 2: 0,66 to 1,23 Volts
- Voltage between earth and track 6: 3,7 to 4,4 Volts
Throttle housing heating element (1270)
Application: EW engine
Role
The heating resistor prevents the throttle housing from icing up
Description
The sensor consists of a Positive Temperature Coefficient resistor (PTC)
The sensor heating power is controlled according to ambient temperature
12 volts supply
Air temperature sensor (1310)
Application: EW engine
Role
The air temperature sensor informs the ECU of the temperature of the air admitted
The role of the injection ECU in terms of the information received
- Calculate the density of the ambient air
- Determine the quantity of fuel to be injected
Description
The sensor consists of a Negative Temperature Coefficient (NTC) resistor
The more the temperature increases, the more its resistance value is reduced
Electrical special features
Electrical features
- Resistance at 20 °C = 6250 ohms
- Resistance at 80 °C = 600 ohms
Inlet manifold pressure sensor with integrated temperature sensor (1312)
Application: TU engine
The inlet manifold pressure sensor and the air temperature sensor are incorporated in a single part
Role
The functions are identical to those of separate sensors
Description
"a": air entry
Electrical special features
Allocation of channels of connector
- Terminal 1: signal (inlet manifold pressure sensor)
- Terminal 2: 5 Volts
- Terminal 3: signal - air temperature sensor
- Terminal 4: earth
Electrical features, inlet manifold pressure sensor (measurement between channel 1 and channel 4): pressure of 1 bar = pressure of 4,5 bar
Electrical features, air temperature sensor (measurement between channel 3 and channel 4)
- Resistance at 20 °C = 2500 ohms
- Resistance at 80 °C = 300 ohms