What is the most likely cause if the BAR 97 dynamometer will not pass calibration?

• A. Dirty filters.
• B. Worn tires.
• C. Low coolant.
• D. Faulty fuel pump.

Answer: (A)

Calibrating the BAR 97 dynamometer relies on the engine drawing a consistent, known amount of air and producing predictable exhaust signals that the test equipment can compare to references. If the air path is restricted, such as by dirty air filters, the engine won’t breathe as designed. That changes the air/fuel balance and the exhaust characteristics during the calibration run, leading the dynamometer’s readings to drift from the expected values and causing the calibration to fail. Cleaning or replacing the dirty filters restores proper airflow and allows the system to reach the correct operating conditions needed for a pass.

Worn tires could affect traction and how the load is applied, but the calibration process can usually account for normal tire wear. Low coolant or a faulty fuel pump would tend to cause overheating or fuel delivery problems that show up as drivability issues rather than a direct, common cause of calibration failure in this setup.