Car engine tuning is the process of keeping a car’s engine running as close to perfectly as possible. There are two basic types of car engine tuning. The first is stock tuning and the second is high performance tuning. Stock tuning is the kind of tuning that you will see at the dealership, with various engine parameters set to specifications that the manufacturer has decreed to be optimal. Performance tuning goes one step further and modifies the manufacturer’s specification to enhance the performance capabilities of the engine. Ignition timing, air-fuel ratios and spark plug gaps are just a few items that can be changed in performance tuning. For those wanting to really increase performance, there are modified computer chips available.
For more info, see The Engine Chip Tuning Guide