A tuner is a handheld device that connects to the OBD2 port in your Tacoma (located under the dash below the steering wheel or above the parking brake pedal). Depending on the type of tuner, it can either be a touchscreen device similar to a smartphone or a simple electronic gadget with a smaller LCD screen. Power tuners or flash tuners can load a custom tune, diagnose engine trouble codes, adjust the transmission shift points, and provide on-screen monitoring or data logging functions - the latter of which can be transferred to a laptop for further analysis.
Tacoma handheld tuners will come with either pre-loaded, customized, or downloadable tunes to alter the injection timing, fuel pressure, ignition timing, valve timing, throttle sensitivity, and other settings in your truck depending on what the purpose of the tune is. For example, Tacoma owners that want to squeeze more performance from their trucks will use a performance-based tune that will make the ignition, timing, and fuel cycles more aggressive than stock in order to produce more horsepower and torque.
If you are thinking about buying a tuner to enhance the performance characteristics of your Tacoma, make sure to specify the make, model, and engine size. This ensures a smooth and problem-free tuning experience. If your truck is running modified parts (such as a larger throttle body, forced-induction mods, or larger off-road wheel and tires), it is also best to contact the manufacturer so they can create a custom tune that is compatible with the mods in your truck.