When should a visible idle tailpipe smoke check be performed during an ASM smog check inspection?

Performing a visible idle tailpipe smoke check during an ASM (Acceleration Simulation Mode) smog check inspection is critical for assessing the overall condition of the vehicle's emissions system. The correct timing to conduct this check is after the emissions sampling has been completed. This sequence allows inspectors to obtain accurate readings of the emissions first before evaluating the visible tailpipe smoke.

After the emissions sampling, any visible smoke is then assessed, which can indicate issues such as oil burning or fuel mixture problems. Conducting the smoke check at this point helps ensure that the initial test results reflect the vehicle's standard operating conditions without interference from any transient readouts that could occur during sampling.

Other timings for the visible idle tailpipe smoke check might not provide the most accurate assessment of the vehicle's emissions status. For instance, checking before the emissions have been sampled could lead to misleading conclusions about the vehicle's performance, potentially overlooking critical faults that only reveal themselves under specific operating conditions.