What is ECU Tuning?

Andrew Hughes27/11/19

Modern Engine Tuning is the tuning of an EFI (electronic fuel injection) engine whereby the cars fuel, air and ignition (spark) are all managed electronically using a computer known as an ECU. ECU’s can be broadly broken into two categories

  1. Factory / OEM ECU
  2. Standalone aftermarket ECU (Haltech, Motec etc)

When tuning either of these types of ECU the principals of tuning are the same. These principles apply whether you are tuning a naturally aspirated or turbocharged/supercharged car. When tuning a OEM or Factory ECU this is often called an Engine Remap or alternatively an ECU Flash Tune.

The main thing that a tuner will be doing is adjusting the two most critical elements in a combustion engine process:

  • Air to Fuel Ratio AFR (i.e how much air is mixed with the fuel)
  • Ignition Timing (at what stage in the engine cycle does the spark happen) Usually referred to in degrees of timing.

These two elements are optimised for performance or economy dependent on the needs and wants of the owner and are consistent to both naturally aspirated and turbocharged cars.

The other main element that is “tuned” in a modern ECU specifically in the case of a turbocharged car in particular is the amount of air sent into the cylinder - known as Boost Pressure. By adding more air into the cylinder and combining it with a appropriate amount of fuel delivery and then igniting this at the correct time will result in more torque delivered through the crankshaft and therefore producing more power.

Its important to note that the reason its called “tuning” is because the process isn’t simply “more is better”. Rather it involves fine tuning - employing the science behind engine durability, fuel system capacity, turbocharger size and cylinder compression (two name a few) which all play a factor in determining the optimal fuel to air ratio, ignition timing and potentially boost pressure to ensure the engine produces the amount of power it is capable of producing without creating detrimental consequences to your engine.

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