Flow chart
Air circulation (as per arrows)
- A: air
- B: exhaust gas + air
- C: exhaust gas
WarningThe diagram relates to engines with a controlled turbo (injection ECU + electrovalve)
| reference | designation | part number in the electrical diagrams | remarks |
|---|---|---|---|
| 1 | injection ECU | 1320 | - |
| 2 | recycling regulation electrovalve (EGR) | 1253 | - |
| 3 | vacuum pump | - | - |
| 4 | turbocharging pressure regulation solenoid valve | 1233 | according to specification |
| 5 | exhaust gas recycling valve (EGR) | - | - |
| 6 | air inlet manifold | - | - |
| 7 | exhaust gas manifold | - | - |
| 8 | boost pressure waste gate | - | vacuum-controlled |
| 9 | pneumatic control capsule for the waste gate (on turbocharger) | - | vacuum-controlled |
| 10 | catalytic converter | - | - |
| 11 | exhaust turbine | - | - |
| 12 | turbocharger | - | - |
| 13 | air inlet turbine | - | - |
| 14 | air flow meter + air temperature sensor | 1310 | - |
| 15 | air cleaner | - | - |
| 16 | inlet manifold pressure sensor | 1312 | - |
| 17 | air/air heat exchanger | - | according to specification |
| 18 | atmospheric pressure sensor (integrated in the injection ECU) | 1320 | - |
NoteEGR: exhaust gas recycling device
Air cleaner
Replacement intervals: every 60 000 km
Turbocharger
Role
The turbocharger allows the engine to be turbocharged with air
There are 2 assembly possibilities
- Boost pressure controlled by the injection ECU and the electrovalve
- Boost pressure regulated by the waste gate only
Description
D: non-controlled turbocharger
E: controlled turbocharger (injection ECU + electrovalve)
A: to the inlet manifold
B: gas from the exhaust manifold
(1) injection ECU
(3) vacuum pump
(4) turbocharging pressure regulation solenoid valve
(8) boost pressure waste gate
(9) pneumatic control capsule for the waste gate: vacuum-controlled
(11) exhaust turbine
(13) air inlet turbine
(19) pneumatic control capsule for the waste gate: pressure-controlled
The turbocharger consists of two separate chambers
The turbocharger consists of the following components
- A chamber connected to the engine exhaust function
- A chamber connected to the inlet function
- A turbine and a compressor, connected by a shaft
The turbine, activated by the exhaust gas, drives the compressor which compresses the inlet air
NoteTurbocharger lubrication: the very high speeds of the moving parts and temperatures demand a careful lubrication
The pressurised oil required for this function is taken from the engine oil circuit
WarningBefore stopping the engine, it is essential to allow the engine to return to idle. failure to observe this condition may cause the destruction of the turbocharger (lack of lubrication)
The turbocharge pressure is regulated by the waste gate valve
The boost pressure can be regulated in 2 ways
- D assembly: at rest the waste gate is closed
- E assembly: at rest the waste gate is open
Description: D assembly
The boost pressure is regulated according to the air pressure in the inlet manifold
Operating phases once the pressure value of the pneumatic capsule (19) has been exceeded
- The boost pressure waste gate opens
- The exhaust turbine speed decreases
- The boost air pressure decreases
The decrease in the boost pressure causes the boost pressure waste gate to close
Description: E assembly
The boost pressure is regulated by the electrovalve (4) controlled by the injection ECU (1)
WarningThe waste gate is open when it is not being pneumatically controlled (vacuum)
The increase in pressure in the inlet manifold is obtained by closing the waste gate
Operating phases once the injection ECU prevents operation of the electrovalve (4) in order to limit the boost pressure
- The vacuum pump no longer communicates with the pneumatic control capsule (9)
- The boost pressure waste gate opens
- The exhaust turbine speed decreases
- The boost air pressure decreases
(1320) atmospheric pressure sensor
Role
The sensor measures the atmospheric pressure
The role of the injection ECU in terms of the information received
- To determine the air density
- To prevent recycling when driving at high altitude
NoteThe density of the air decreases according to the altitude
Description
The sensor is of the piezo-electric type
The sensor consists of stress gauges
The sensor supplies a voltage proportionate to the atmospheric pressure
Location
The atmospheric pressure sensor (18) is integrated in the injection ECU
WarningThe atmospheric pressure sensor can not be separated from the injection ECU
Air/air heat exchanger
Role
The air/air heat exchanger cools the air entering the cylinders in order to increase the air density within the cylinders
Due to the increase of the air density, the motor's performances increase
Location
Location: on the front panel of the vehicle
Inlet manifold pressure sensor (1312)
Role
The sensor enables to determinate the air pressure in the intake pipe
The role of the injection ECU in terms of the information received
- Regulate the boost pressure (*)
- Regulate the HP fuel pressure
- Regulate the duration of injection (fuel flow)
(*) controlled turbocharger (injection ECU + electrovalve)
Description
C: air entry
The sensor is connected to the inlet air circuit at the air/air heat exchanger
The sensor is of the piezo-electric type
The sensor consists of stress gauges
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 1,3 bar = output voltage of 1 volt
Vacuum pump
Role
The vacuum pump supplies the vacuum required for operating the following components
- Exhaust gas recycling valve (EGR) (depending on the version)
- Pneumatic control capsule for the EGR valve
- Brake servo (depending on the version)
Description
The vane-type vacuum pump is driven by the engine camshaft
(3) vacuum pump
(20) safety valve (the valve is integrated in the outlet union)
A safety valve integrated in the pump isolates the brake vacuum circuit with the engine switched off
The safety valve allows the following to be retained
- A vacuum reserve in the brake servo
- Braking assistance for several applications of the brake
Location
Location: on the cylinder head at the end of the camshaft, gearbox side
Turbocharging pressure regulation solenoid valve (1233)
Vehicle application: vehicles with boost pressure controlled by the injection ECU
Role
The regulating electrovalve controls the boost pressure waste gate
Role of the boost pressure regulating electrovalve
- Regulate the boost pressure
- To limit the boost pressure
Regulation of the boost pressure is progressive and is controlled by mapping (injection ECU)
Description
(21) electrical connector
D: "user" outlet
E: pressure drop inlet for the vacuum pump
F: white marking
G: atmospheric pressure inlet
The solenoid control is an OCR (Opening Cyclical Ratio) type control
The proportional electrovalve controlled by an OCR voltage is connected to the following components
- Atmospheric pressure
- Vacuum supplied by the vacuum pump
The pressure supplied by the electrovalve is included between the atmospheric pressure and the vacuum pump vacuum
Electrical special features
Control: injection ECU (earth)
Variable voltage control (OCR)
- Full supply (maximum OCR) = maximum vacuum
- No supply (minimum OCR) = no vacuum (atmospheric pressure)
NoteOCR: opening cyclic ratio
Location
(4) turbocharging pressure regulation solenoid valve
The electrovalve is located in the engine compartment