Renault Megane Quiz
Engine and peripherals

Throttle body: General

In this manual: Engine and peripherals
Engine and peripherals — 141Chassis — 79Chassis — 72Renault Mégane III Driver's Manual — 87Electrical equipment — 221Engine and peripherals — 47Electrical equipment — 80Transmission — 14Air conditioning — 30Bodywork — 115Trim and upholstery — 44General vehicle information — 27Air conditioning — 59General vehicle information — 16Transmission — 38Sealing and soundproofing — 7General vehicle information — 3
~2min read

I - THROTTLE BODY

The throttle body controls idle speed regulation and modulates engine air filling. It consists of an electric motor and two throttle position sensors.

When the engine is at idle, throttle position is regulated according to the idle speed setpoint. This setpoint takes into account major consumers (air conditioning) and operating conditions (air and coolant temperature).

When the driver presses the accelerator pedal, the request is converted into a throttle opening position.

However, to improve driveability, the throttle opening is not directly proportional to the driver's request.

To eliminate jerking, make gear changes easier and support safety functions, the throttle body modulates engine torque.

II - THROTTLE BODY DEGRADED MODES

There are four types of throttle body degraded modes.

1 - Performance limitation mode

This mode covers electrical faults for which a viable fallback solution exists for the injection system (loss of one of the two tracks of the pedal or throttle body potentiometer). This mode limits acceleration and restricts maximum throttle opening (maximum speed of 90 km/h and 100 km/h).

2 - Loss of driver demand mode

This mode is also called "electrical limp-home position". This mode is applied when the accelerator pedal signal is completely lost, but the injection ECU still controls engine air filling (throttle control remains operational). In this mode, the injection ECU sets a specific accelerator pedal position for each gear and sets idle speed when the brake pedal is pressed.

In this case, the maximum engine speed in neutral is 2500 rpm.

3 - Mechanical limp-home position mode

This mode covers faults that result in loss of throttle control (throttle command impossible). In this case, the throttle returns to its mechanical rest position, the injection ECU limits engine speed by fuel cut-off and limits torque by cylinder cut-outs (ignition and injection) depending on the accelerator position.

Thus the maximum engine speed with the pedal fully depressed or in neutral is 2500 rpm.

4 - Pedal follow mode

If the intake manifold pressure signal is lost, the throttle opening is directly proportional to the accelerator pedal position.

Note: Each of these modes causes the injection fault warning light to illuminate on the instrument panel.

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