What Is EFI Tuning?
Tuning (also referred to as engine tuning or Dyno Tuning) is the process used to alter the stock computer, and ultimately, how a car runs. This is typically done after adjustments to the car's stock configuration have been made. For example, if a turbo kit was installed on a car that was not equipped with one from the factory, tuning would be necessary to make it run properly and safely again.
Reasons for Tuning
Stock engine computers are tuned to specifically operate a car with the factory setup. After adjustments are made to that stock configuration, the computer operating the engine needs to have various parameters adjusted including but not limited to: fuel and ignition (or timing) maps for that specific setup.
This is perhaps the most important step of modifying a car. The tune essentially brings everything together by getting the performance parts that have been installed to safely perform at their best. This is done on a case by case basis and is exact to each setup. Performance and reliability are the two main products of a good tune. After tuning is complete, the car is finally ready to endure what it was built for. This process ensures that the car will perform without hesitation or hiccups and can withstand more spirited driving without concern for immediate consequence.
When To Have Tuning Done
Tuning should be done when making modifications that will change the amount of air or fuel passing through an engine. These adjustments can have a lasting negative effect if not quickly tuned properly. If you have recently installed or changed any of the following you should consider tuning immediately:
Larger fuel injectors
Higher compression pistons
Ported cylinder head
How To Get Started
To be able to have your car tuned, you need to equip it with a compatible Engine Management System (EMS). The four most common systems and methods are piggy-back tuning systems, a modified stock engine control unit (ECU), flashing the stock ECU, or a standalone ECU.
A piggy-back system uses the factory ecu, but monitors certain engine parameters from the factory ecu and sends a modified injector or ignition output to achieve a desired air/fuel or ignition value. Piggyback systems can often times have poor running conditions due to "tricking" the factory ecu into doing something it was not intended to do.
Examples: Emanage, Split Second, AEM F/IC.
Modified Stock ECU
A modified stock ECU is typically one that is eeprom "chip" based. Using a real time programmer in place of the eeprom chip on the ECU board, a custom tune can be performed. A modified stock ECU allows for direct control over all functions of the factory ECU, so excellent performance, fuel economy, and overall running can be achieved.
Examples: Hondata S300 and KPro.
Most newer cars are able to be "flashed" through the factory OBD-II scan port. Flash tuning an ECU allows for direct control over all functions similar to a modified stock ECU, but without the need to remove/modify the ECU. Flash tuning is often times the best choice for tuning on newer cars due to being able to retain emissions functionality and cost.
Examples: COBB AccessPORT, Hondata FlashPro and Open Source tuning software.
A standalone ECU is a direct replacement of the factory ECU. It manages all functionality that the OEM ECU did previously, but often times adds more control or features that the OEM ECU would not otherwise be able to provide. Standalone systems often provide the absolute best control over tuning for an engine, but have the highest cost associated with them.
Examples: AEM EMS, Haltech, MoTeC, PowerFC, FAST XFI.