How to Control the Throttle to Maintain a Fixed Speed?
4 Answers
You can control the vehicle's speed by adjusting the pressure applied to the throttle pedal. The car's throttle regulates the engine's throttle valve opening, which in turn controls the engine's air intake and fuel injection, thereby managing the engine's RPM. Below is some extended information about the throttle: 1. The throttle is essentially an air valve on the engine, a device that controls the airflow. 2. For proper combustion, the engine requires an appropriate air-fuel ratio, typically 14.7:1, meaning 14.7 liters of air to 1 liter of fuel. This ratio ensures optimal engine combustion. 3. The so-called throttle controls the airflow, and once the air volume is determined, the required fuel amount is calculated automatically by the car's internal computer. 4. When you press the throttle, the airflow increases, leading to more fuel injection and greater combustion force, which results in higher engine RPM. Conversely, releasing the throttle reduces the RPM.
As a seasoned driver with over 200,000 kilometers of experience, I believe maintaining constant speed through throttle control relies on three key anticipatory skills: reading road conditions, subtle ankle adjustments, and visual management. On highways, I anchor my heel to the floor and only apply gentle pressure with the ball of my foot - this prevents fatigue-induced shaking. When spotting an uphill ahead, I proactively increase throttle by about 1cm; before descents, I ease off early to coast on momentum. The golden rule is scanning 200 meters ahead - the moment I detect traffic slowing, I lift off rather than waiting to brake hard. Regular tire pressure checks and throttle body maintenance also help, as underinflated tires increase fuel consumption forcing constant throttle corrections.
To maintain a speed of 80 km/h for an extended period, you first need to understand your car's characteristics. When driving a manual transmission, I choose to cruise steadily in fifth gear, listening to whether the engine sound remains stable after pressing the accelerator. Automatic transmission cars rely more on pedal feel—for example, Japanese cars have sensitive throttle response, requiring only a light touch on the pedal, while German cars with turbo lag need the accelerator to be pressed half a second earlier. Additionally, for every 5 km/h change in speed, I make a mark on the seat to remind myself to adjust my foot position. Turning on the AC or carrying a full load increases resistance, requiring about 10% more throttle input. Neglecting these details can cause speed fluctuations.
The most annoying thing during weekend family outings is inconsistent speed. The trick I've figured out is: accelerate to the target speed on flat roads, then maintain a fixed throttle angle, such as tilting the foot at 30 degrees with gentle pressure. Observing the uniform movement of roadside reference objects through the rearview mirror is safer than staring at the dashboard. Adjust accordingly for different loads; for example, when the back seat is fully occupied by three people, the throttle depth should be about 15% more than when the car is empty. Remember to regularly clean the floor mat under the throttle pedal—once, a stuck mat caused me to exceed the speed limit by 12 km/h without realizing it the entire time.
