What is tuning all about?

Tuning is the art of configuring your engines sensors, engine control unit (ecu), or carbuerator jettings to extract the full potential of your engine without sacrificing driveability and fuel economy.

The engine acts by combusting the mixture of air with fuel and producing power, by having the correct mixture, dependent on engine modification, the full potential of the engine is harnessed.


What is an Air/Fuel Mixture?

A combustion engine produces power by mixing the induced air with fuel, mixtures go from 20:1, 20 parts air to 1 part fuel, up to 9:1 AFR.  With the 20:1 AFR being on the lean side and the 9:1 AFR on the rich side. For best fuel economy, engines are tuned at a ratio of 14.7:1 or somewhere near to that.  However, this does not hold true 100% of the time.

A sample of a tuned Air/Fuel Mixture will look like:



While before tuning, Air/Fuel mixtures can look like:



What is closed-loop mode?

Closed-loop is when your ecu relies on the engines oxygen sensor (narrow band) to receive feedback of the engines air/fuel mixture.  Then ecu then corrects the mixture to target a ratio of 1 lambda or 14.7:1 for gasoline engines.  This mode works only on low load conditions on the engine and this condition depends from one engine to another.


What is open-loop mode?

Open-loop is when your ecu cuts off from receiving feedback from the oxygen sensor and relies on the mappings stored on your ecu.  This mappings is like an excel spreadsheet, with columns and rows, and different tabs.  Tabs would be considered for Low Load, Low Cam, High Cam, High Load fuel map, then an ignition map follows for each.  The maps depend again from one ecu to another.


What is tuned by garageTUNED?

garageTUNED modifies your Air/Fuel Mixture to target somewhere 12:1 AFR to 12.5:1 AFR for turbocharged/supercharged engines, while a ratio between 13:1 AFR to 13.5:1 AFR for Normally Aspirated Engines.  This ratio is then again dependent on where the engine makes most power.

For cars with engine management systems that are capable of controlling ignition timing, garageTUNED modifies this also.