At idle, the throttle position is set depending on the set idle speed, which depends on the number of powerful power consumers turned on (air conditioner) and engine operating conditions (air and coolant temperature).
When you press the accelerator pedal, the throttle valve opens to the appropriate angle.
However, in order to improve driving comfort, the throttle opening is not directly proportional to the driver's control input.
To eliminate jerking, facilitate shifting and ensure safety, the throttle valve allows you to change the engine torque.
Throttle valve standby modes
There are four standby throttle body modes.
Dynamic performance limitation mode
This mode is used for malfunctions in electrical circuits for which there is a safe solution suitable for the injection system (malfunction of one of the two conductive paths of the accelerator pedal position sensor or throttle body). This mode limits acceleration performance and maximum throttle opening (maximum speed 90 km/h for vehicles with manual transmission and 100 km/h for vehicles with automatic transmission).
Driver Loss of Control Mode
This mode is also called «standby electrical position». This mode is used when there is no information about the position of the accelerator pedal, but the injection ECU continues to control the air filling of the engine cylinders (throttle actuator remains controlled). In this mode, the injection ECU sets the accelerator pedal positions for each gear and sets the engine to idle when the brake pedal is pressed. In this case, the maximum speed of the crankshaft in the neutral position of the gearbox is limited to 2500 rpm.
Standby mechanical position mode
This mode is used for malfunctions that lead to loss of throttle control (damper actuator does not work). In this case, the throttle valve is in the mechanical rest position, the injection ECU limits the engine speed by stopping injection and the torque by deactivating the cylinders (stop ignition and injection) depending on the position of the accelerator pedal. As a result, the maximum crankshaft speed in full load mode or in the neutral position of the gearbox remains equal to 2500 rpm.
Pedal tracking mode
In case of loss of information about the pressure in the intake manifold, the degree of opening of the throttle valve is directly proportional to the position of the accelerator pedal.
Note. When switching to any of these modes, the signal lamp for a malfunction of the injection system lights up on the instrument panel.
Idle speed correction depending on the coolant temperature (M4R engine)
* Except when the engine is started at a temperature of 15-30°C.
Idle speed correction depending on the coolant temperature (K4M engine)
* Except when the engine is started at a temperature of 15-30°C
Idle speed correction depending on battery voltage and electrical energy balance
The engine idle speed correction compensates for the voltage drop when the electrical consumer is switched on if the battery is weakly charged. The correction starts when the voltage becomes less than 12.7 V. As a result of the correction, the engine speed can be increased by no more than 160 rpm, i.e. up to 910 rpm.
Correction of frequency of rotation of idling at malfunction of the gauge of absolute pressure
If the absolute pressure sensor malfunctions, the idle speed increases to 1024 rpm.
If the engine is started at a coolant temperature of 15°C-30°C and then remains at idle, a gradual reduction in engine speed may occur. This is due to the presence of a function to reduce the toxicity of exhaust gases when starting the engine (inclusion of elements of heating of oxygen sensors).