Until recently, throttle control systems were almost always very simple. The gas pedal was mechanically connected to the throttle and pressing it would open the throttle. Most vehicles accomplish this feat with a throttle cable and linkage, although a few use more complex rigid bar and linkage systems. In any case, there has always been a direct physical connection between the foot and the throttle.

Electronic engine management made things more difficult during the 1980s, but components such as throttle position sensors were simply designed to allow the computer to make changes. Throttle controls remained entirely mechanical, and physical cables and connections were still the order of the day.

How does electronic throttle control work?

Electronically controlled throttles work just like traditional throttles, but there is no physical cable or lever connecting the gas pedal to the engine. When the accelerator pedal is depressed in a vehicle that uses technology » electric drive» the sensor transmits pedal position data. The computer can then use this information to change the throttle position.

In addition to the actual position of the gas pedal, the computer may also rely on a variety of other information to determine the best course of action. Instead of simply opening or closing the throttle in direct response to pedal position, the computer can analyze the vehicle’s current speed, engine temperature, altitude, and other factors before opening or closing the throttle.

Why do you need electronic throttle control?

Like many advances in automotive technology, the main goal of electronic throttle control is to improve efficiency. Because electronic throttle control technology can rely on multiple sensor inputs, these systems can operate at much higher efficiency than vehicles that use traditional throttle controls.

The use of electronic throttle control technology can lead to improved fuel economy and reduced exhaust emissions, mainly due to greater control of air/fuel mixtures. This, of course, is due to the fact that these systems are capable of both setting the throttle position and adjusting the amount of fuel, while traditional systems can only adjust the amount of fuel to match the throttle position.

Electronic throttle control can also be easily integrated with technologies such as cruise — control , electronic system stability control and traction control, which can improve handling and enhance security.

Is electronic throttle control safe?

Whenever any technology placed between the driver and the vehicle they are driving, this creates the potential for at least some level of risk. When you drive a car that uses traditional throttle controls, you usually rely on a Bowden cable to actuate the throttle. This type of cable consists of wires inside a plastic sheath and they fail regularly. The cable can get stuck in the sheath, or it can wear out and eventually break. The end of the Bowden cable can also come loose, rendering it useless.

In most cases, a faulty throttle cable will result in the car not being able to accelerate. If this happens at freeway speeds, it can lead to a very dangerous situation. However, it is relatively rare for a traditional throttle cable to get stuck in the open position.

With electronic throttle control, the main concern is the throttle sticking open or the computer erroneously ordering the throttle open. Modern electronic throttle controls are designed with the express purpose of avoiding situations like this, but a number of high-profile cases have raised concerns.

Electronic throttle control and sudden unintended acceleration

When a vehicle accelerates without any intentional intervention from the driver, it is called «sudden unintentional acceleration». Some potential causes of sudden unintentional acceleration include:

Many cases of sudden unintentional acceleration are pedal grabbing, which can easily happen if the floor mat slides forward and interferes with normal pedal operation. This may cause the accelerator pedal to be depressed, but may also cause the brake pedal to malfunction.

According to NHTSA, a number of cases of SUA also occur when the driver accidentally presses the gas instead of the brake. This was the case in the case of an Audi recall in the 1980s, when the German automaker increased the distance between the gas and brake pedals.

With electronic throttle control, the problem is that the computer can open the throttle whether or not the brake pedal is depressed. This would create an incredibly dangerous situation, especially in a vehicle that also used brake-by-wire technology, although this is still a hypothetical issue. While Toyota recalled a number of vehicles that used ETC systems due to the SUA issue in 2009 and 2010, there was no no convincing evidence that that their electronic throttle control technology was flawed.

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