Rough Idle Diagnosis: Separate Air, Fuel, Ignition, and Mechanical Causes
Use scan data and controlled condition changes to separate an all-cylinder idle problem from a cylinder-specific fault before cleaning or replacing parts.
Tag misfire
Reading Spark Plugs: Compare Cylinders, Then Confirm the Cause
Use spark-plug appearance as cylinder-specific evidence, preserve plug position, and confirm fouling, overheating, or deposits with scan and mechanical tests.