Why it matters: O2 sensors feed critical data to your ECU, helping maintain the ideal air-fuel ratio for performance, efficiency, and emissions control. Reading the signals: Healthy upstream sensors ...

Fuel trim data is one of the most powerful yet underused tools in automotive diagnostics. By learning to interpret short-term and long-term fuel trim readings, technicians and DIYers can spot vacuum ...

There's an old saying in engine tuning that when adjusting the mixture of your engine you can be too rich a bunch of times, but only too lean once. With that in mind, determining the air-fuel ratio ...

It used to be that tuning a hot street engine or race motor was one of those black arts that only those carburetor and ignition wizards seem to understand. When (and why) an engine needed more or less ...