An excessive ______ reading may indicate a fuel calibration concern.

An excessive ______ reading may indicate a fuel calibration concern.

• A. PWM
• B. MAP
• C. IAT
• D. TPS

Answer: (A)

The key idea is that fuel calibration is controlled by how long the fuel injector stays open each cycle, known as the injector PWM duty cycle. This PWM value directly determines how much fuel is delivered. If the reading from this PWM signal is excessively high for the current engine operating point, it points to a fuel calibration issue—for example, the ECU may be using an incorrect injector size, wrong fuel-pressure data, or a mis-tuned fuel map that calls for more fuel than the engine actually needs. Other sensor readings like MAP, IAT, or TPS influence fueling, but an abnormally high reading from those sensors would indicate different kinds of problems (air density, throttle input, or manifold pressure changes) rather than a direct calibration mismatch. The most direct indicator of a calibration concern is an excessively high injector PWM value, since it shows the ECU is commanding more fuel than appropriate for the air entering the engine.

The key idea is that fuel calibration is controlled by how long the fuel injector stays open each cycle, known as the injector PWM duty cycle. This PWM value directly determines how much fuel is delivered. If the reading from this PWM signal is excessively high for the current engine operating point, it points to a fuel calibration issue—for example, the ECU may be using an incorrect injector size, wrong fuel-pressure data, or a mis-tuned fuel map that calls for more fuel than the engine actually needs.

Other sensor readings like MAP, IAT, or TPS influence fueling, but an abnormally high reading from those sensors would indicate different kinds of problems (air density, throttle input, or manifold pressure changes) rather than a direct calibration mismatch. The most direct indicator of a calibration concern is an excessively high injector PWM value, since it shows the ECU is commanding more fuel than appropriate for the air entering the engine.