Under what condition will a vehicle fail the functional inspection if the ignition timing is adjustable?

• A. 11° BTDC.
• B. 0° BTDC.
• C. 5° ATDC.
• D. 20° BTDC.

Answer: (A)

Ignition timing that can be adjusted is not allowed to pass a functional emissions check. The test requires timing to be fixed to the manufacturer’s specification so it won’t drift and affect combustion and emissions. When the timing is adjustable and the engine is found at a specific setting that shows it can be moved (like 11° BTDC in this scenario), it demonstrates the lack of a locked, spec-defined setting, which is why the vehicle fails. The key idea is that the ability to adjust timing—rather than being fixed to a known spec—fails the functional inspection, because emissions control relies on a stable timing reference.