How To Remove The Speed Governor On A Car

Speed governors, also known as speed limiters, are a common feature in many modern vehicles. They are designed to restrict the maximum speed of the car, often for safety reasons or to meet regulatory requirements. While some drivers appreciate the added layer of protection, others, particularly those interested in performance tuning or track days, may wish to remove or bypass the speed governor. This article provides a detailed technical overview of how speed governors work and the methods used to remove or modify them, keeping in mind the potential risks and legal implications involved. Removing a speed governor can void your warranty, affect insurance, and potentially create dangerous driving situations. Proceed with caution and understand the consequences.

Background: Engine Management and Speed Limitation

To understand how to remove a speed governor, it's crucial to first grasp the fundamentals of engine management systems (EMS) and how they interact with the vehicle's speed control. Modern vehicles rely on a sophisticated network of sensors and controllers to optimize engine performance, fuel efficiency, and emissions. The speed governor is typically integrated into this system, often controlled by the Engine Control Unit (ECU) or Powertrain Control Module (PCM).

The ECU is the brain of the engine. It receives data from various sensors throughout the vehicle, including:

• Vehicle Speed Sensor (VSS): Measures the vehicle's speed, usually located on the transmission or wheel hub.
• Throttle Position Sensor (TPS): Indicates how far the throttle is open, reflecting the driver's demand for power.
• Crankshaft Position Sensor (CKP): Monitors the engine's rotational speed (RPM).
• Mass Airflow Sensor (MAF): Measures the amount of air entering the engine.

Based on this information, the ECU calculates the optimal fuel injection timing, ignition timing, and other parameters to achieve the desired performance while staying within predefined limits, including the speed limit.

Technical Breakdown: How Speed Governors Work

Speed governors work by limiting the engine's power output when the vehicle reaches its maximum allowed speed. There are several methods employed, and the specific approach varies depending on the vehicle's make, model, and year.

1. Fuel Cut-Off

This is one of the most common methods. When the vehicle reaches the pre-set speed limit, the ECU begins to interrupt the fuel supply to the engine. This can be done by momentarily shutting off the fuel injectors or by reducing the amount of fuel injected into each cylinder. The effect is a noticeable "jerking" or hesitation as the engine momentarily loses power, preventing the vehicle from accelerating further. The fuel cut-off method is often quite abrupt and noticeable to the driver.

2. Spark Retard

Another common approach involves retarding the ignition timing. Ignition timing refers to the point in the engine cycle when the spark plugs fire to ignite the air-fuel mixture. By delaying the spark, the ECU reduces the efficiency of the combustion process, resulting in lower engine power. This method is generally less abrupt than fuel cut-off, but it still limits the vehicle's ability to accelerate beyond the set speed.

3. Throttle Limitation

In some newer vehicles, the ECU can directly control the electronic throttle body. Instead of relying solely on the driver's input through the accelerator pedal, the ECU can limit the throttle opening angle when the vehicle approaches the speed limit. This prevents the engine from receiving the necessary airflow to produce more power, effectively limiting the top speed. This method is often combined with fuel cut-off or spark retard for a more comprehensive approach.

4. Gear Limitation

Although less common, some speed governors can be configured to limit the vehicle to a specific gear. This prevents the vehicle from accessing higher gears that would allow it to reach higher speeds. This method is more typically found in vehicles designed for commercial use, such as delivery vans or trucks.

Removing or Modifying the Speed Governor

There are several ways to remove or modify a speed governor, each with its own advantages and disadvantages. These range from simple workarounds to more complex ECU remapping.

1. ECU Remapping (Tuning)

This is the most effective and common method for removing a speed governor. It involves reprogramming the ECU to remove the speed limit parameter. This requires specialized software and hardware, such as an ECU flashing tool and a laptop computer. The process involves connecting the flashing tool to the vehicle's OBD-II port and uploading a modified ECU map (calibration file) that does not include the speed limiter. This is a complex procedure and should only be performed by experienced tuners.

Pros:

• Completely removes the speed governor.
• Can also improve engine performance and fuel efficiency.

Cons:

• Requires specialized equipment and expertise.
• Can void the vehicle's warranty.
• May require modifications to other engine components to handle the increased power.

2. Speed Limiter Removal Modules

These are aftermarket devices that intercept the signal from the vehicle speed sensor (VSS) before it reaches the ECU. The module modifies the signal to indicate a lower speed than the actual speed, effectively tricking the ECU into thinking the vehicle is not exceeding the speed limit. These modules are typically plug-and-play, making them relatively easy to install.

Pros:

• Relatively easy to install.
• Less expensive than ECU remapping.

Cons:

• Can affect other vehicle systems that rely on the VSS signal, such as the speedometer and odometer.
• May not be as reliable as ECU remapping.
• Can cause error codes or check engine lights.

3. Piggyback ECUs

A piggyback ECU is an aftermarket device that intercepts and modifies the signals between the factory ECU and the engine's sensors and actuators. While less common for simply removing speed limiters, they can be used to adjust various engine parameters, including the speed limit. They're often used for more comprehensive engine tuning.

Pros:

• Offers more control over engine parameters than speed limiter removal modules.

Cons:

• More complex to install and configure than speed limiter removal modules.
• Can void the vehicle's warranty.

Common Issues and Maintenance Concerns

Removing or modifying a speed governor can introduce several potential issues and maintenance concerns:

• Increased Stress on Engine and Drivetrain: Removing the speed limiter allows the engine to operate at higher speeds and power levels, which can put increased stress on engine components, the transmission, and the drivetrain. This can lead to premature wear and failure.
• Overheating: Operating the engine at higher speeds for extended periods can lead to overheating, especially if the cooling system is not adequately sized for the increased power output.
• Reduced Fuel Efficiency: Driving at higher speeds generally results in lower fuel efficiency.
• Tire Wear: Higher speeds and aggressive driving can accelerate tire wear.
• Brake Wear: If the vehicle is now capable of higher speeds, more demanding braking will be required, leading to accelerated brake wear and potential brake fade.
• Error Codes and Check Engine Lights: Modifying the ECU or using aftermarket devices can sometimes trigger error codes and illuminate the check engine light.

Do's and Don'ts / Best Practices

Do's:

• Research thoroughly: Understand the implications of removing the speed governor for your specific vehicle model and year.
• Consult with a professional: If you're not experienced with ECU remapping or aftermarket modifications, seek guidance from a qualified mechanic or tuner.
• Upgrade supporting components: If you plan to significantly increase the engine's power output, consider upgrading other components, such as the cooling system, brakes, and tires.
• Monitor engine parameters: Use a scan tool or aftermarket gauges to monitor engine parameters, such as coolant temperature, oil pressure, and air-fuel ratio.

Don'ts:

• Attempt ECU remapping without proper training: Incorrect ECU programming can damage the ECU and render the vehicle inoperable.
• Ignore warning signs: Pay attention to any unusual noises, vibrations, or performance issues after removing the speed governor.
• Drive recklessly: Removing the speed governor does not make you a better driver. Drive responsibly and obey traffic laws.
• Neglect maintenance: Regularly inspect and maintain the vehicle to ensure it is in good working order.

Conclusion

Removing or modifying a speed governor can provide access to the vehicle's full performance potential, but it's a decision that should be carefully considered. Understand the technical aspects involved, the potential risks, and the legal implications. If you're unsure about any aspect of the process, consult with a qualified professional. While the allure of unrestricted speed can be tempting, remember that safety and responsible driving should always be the top priorities. Given the complexity and potential risks involved, seeking professional assistance for ECU remapping or other modification methods is strongly recommended. Modifying or removing safety features like a speed governor carries significant responsibility. Always prioritize safety and legal compliance.