The speed limiter is an ECU function that caps maximum vehicle velocity. It operates by reducing torque request or implementing fuel/ignition cut when the speed threshold is reached. Most European vehicles are limited to 250 km/h.

Vue d'ensemble

The ECU monitors vehicle speed via wheel speed sensors or transmission output. When approaching the limit, torque is progressively reduced for smooth deceleration.

Controlled Signals

• Vehicle speed (CAN)
• Wheel speed sensors
• Torque request reduction
• Fuel cut (in some systems)

Maps Involved

• Speed Limiter Threshold
• Torque Reduction Ramp
• Gear-specific Speed Limits (some vehicles)

Logic Sequence

Vehicle Speed → Compare to Limit
         ↓
If approaching limit → Begin torque reduction
         ↓
If at limit → Hold torque/speed
         ↓
If over limit → Aggressive reduction

Calibration Objectives

• Smooth speed limiting without abrupt cutoff
• Match vehicle tire speed rating
• Consider cooling system capability

Calibration Strategy

• Raise or remove speed limiter for track use
• Verify tire speed rating matches new limit
• Consider aerodynamic stability at high speed

Diagnostics

• Speed sensor faults may affect limiter
• CAN communication issues

Best Practices

• Speed limiter removal is for track use only
• Ensure vehicle is capable of sustained high-speed operation
• Verify insurance implications