Description - function: engine ECU — variant 2 Citroen C4 Aircross I

Description

(1) engine ECU

"a" 64-way grey connector

"b" 48-way grey connector

Role

The engine ECU manages the fuel injection on the basis of the information on engine torque

• The engine management ECU calculates the engine torque requirement from the accelerator pedal position sensor
• The engine torque request takes account of a number of corrections (torque absorbed by the alternator, torque absorbed by the aircon compressor,...)
• The engine torque request converts into a fuel injection time, a fuel injection phasing, a command to open the throttle unit and an ignition advance

The engine ECU manages the ignition as well as the injection of the fuel, as a function of the different parameters received

• Engine speed
• Position of the crankshaft
• Inlet air pressure (pressure sensor)
• Position of the accelerator pedal
• Engine temperature (coolant thermistor)
• Temperature of the air entering the cylinders (air temperature sensor)
• Engine coolant temperature
• Torque absorbed by the alternator
• Torque absorbed by the aircon compressor (calculation)
• Vehicle speed (vehicle speed sensor; speed information provided by the ESP ECU)
• Oxygen content in the exhaust gases (upstream oxygen sensor)
• Engine knock (knock detector)
• Air conditioning request (*)
• Battery voltage
• Pressure in the power steering circuit

Using this information, the engine ECU operates the following commands

• Opening of the motorised throttle unit
• Adjustment of idling speed
• Ignition advance and coil charging time
• Quantity of petrol injected, proportional to the injectors opening time
• Petrol vapours recirculation (canister bleed electrovalve)
• Cutting of the injection in overload and deceleration
• Air conditioning cut-off
• Oxygen sensor heating resistor (upstream oxygen sensor, downstream oxygen sensor)

The engine ECU controls also the following functions

• Reduction of engine torque during an activation of the ESP (*)
• The engine cooling
• The cooling requirement for the air conditioning (BRAC)
• The dialogue with the ECUs on the CAN network (Controller Area Network)
• Check functionalities of injection and pollution control
• Driving improvement strategies
• Engine immobiliser function
• Emergency strategies
• Fan unit and warning lamp operating management
• The diagnostic with memorisation of failures
• The cruise control and speed limiter function (*)

Electrical features

Programming - initialisation

The engine management ECU software is updated by downloading (ECU fitted with a flash EPROM)