What is an Electronic Throttle Controller?
Electronic throttle control is a system integrated into the car’s main computer, the Engine Control Unit (ECU). It uses a control module operated by the accelerator pedal and an electronic throttle body (Air Control Valve – ACV) on the engine.
The Electronic Fuel Injection (EFI) system is also controlled by the ETC. All three devices and systems work together to provide precise engine speed regulation. When you press the accelerator pedal, the ETC system opens the ACV’s internal throttle, allowing more air into the engine, while the EFI increases fuel flow. This makes the engine go faster.
At the same time, the ECU adjusts the engine valve and ignition timing according to a programmed profile, ensuring smooth, powerful engine acceleration.
The ETC also determines the engine speed during warm-up immediately after starting, regardless of the accelerator pedal position. The engine’s idle speed is automatically increased, ensuring smooth cold running and minimizing the leakage of unburned fuel from the engine to the catalytic converter. In this way, emissions during cold start conditions are kept to a minimum.
Most air control valves have a Throttle Position Sensor (TPS). The TPS sends a signal back to the ECU to ensure that the air valve is responding exactly as the ECU commands it.
In sports and performance cars, the ETC may be designed to include multiple operating modes that the driver can select. These modes may be:
1. The so-called “Normal Mode” is suitable for most driving situations and offers the best fuel economy.
2. “Sport Mode” changes the ETC throttle position profile, resulting in quicker throttle response during acceleration.
3. The next step is “Track Mode”. This is intended to further improve performance.
These alternative modes also include changes to the valve and ignition timing profiles. Of course, the choice of power settings reduces fuel consumption but does not negatively impact emissions. This multi-mode capability increases the driving enjoyment of most car enthusiasts.
Even the smartest ETC can fail. This is where the Throttle Control Warning Light (TCL) comes in handy.
