You likely have noticed that a significant number of vehicles that have come into your shop lately have six-digit odometer readings. What this could mean is that a mechanical integrity issue may be the cause of a misfire code or a misfire symptom.
A variety of noise and vibration levels exist in the normal operation of any vehicle. When noises and/or vibrations are perceived by the customer, the vehicle ends up in your shop, and it’s up to you to determine the cause and repair.
For an engine to run most efficiently and supply the catalytic converter with the proper gasses, it can convert to non-harmful emissions, the engine’s air-fuel ratio must run as close to the proper stoichiometric ratio as possible.