What is an ECU remap?

Quite simply, an ECU remap is a method of gaining more power out of an engine by updating the electronic management system. The ECU (electronic control unit) is remapped with a different set of instructions that help the engine run more efficiently and generate more power. It’s a very cost effective way of boosting your car’s power and can cost just a few hundred pounds.  In terms of pure performance for your money there’s not much to beat a quick ECU remap.

Car makers build millions of engines for many different markets and so they have to be designed to handle a range of different factors, including different grades of fuel and various climates, but there are other pressures such as the need to reduce harmful exhaust emissions. Manufacturers will often set the engine control unit so that the engine is capable of passing the stringent EU emissions tests with a low emissions rating, meaning the car will fall into a lower road tax and company car tax band, but this is not necessarily the best setting for an engine to run at it’s best in the real world.

This gives an engine tuner the chance to improve an engine’s efficiency by reprogramming the electronic control unit to better match the market in which it is being used. By programming the engine to run with the specific grade of fuel and the air temperatures of the car’s home market it can gain faster throttle response, produce more power and torque, and even use less fuel.

Just about any car with an electronic engine management system can be given an ECU remap, and that applies to both petrol and diesel engines. Results can vary but an ECU remap will always produce the best results when applied to a turbocharged or supercharged engines. This is because raising the boost pressure of the turbocharger or supercharger allows much higher gains in power to be achieved, when combined with the correct ignition timing and fueling adjustments.

However, it is sometimes possible to achieve significant power gains in naturally aspirated engines. Some manufacturers offer the same engine in different models with varying levels of power, and this is done by detuning the engine with a different ECU map. This allows the tuner to remap the ECU to release the same level of power as the higher tuned version. An example of this is the 2.0-litre petrol engine found in the Volkswagen Golf, which is a detuned version of the same engine found in the Golf GTI.

Upgrading the ECU of a modern car is a relatively simple task. Most modern cars have a diagnostic port somewhere in the engine bay or dashboard to allow mechanics to download error codes from the ECU when the car is in for service, and this same port can be used to upload the new ECU remap using a computer or special tuning devices. Some older cars will require the original chip on the ECU to be removed and reprogrammed, which requires more technical expertise and can make the upgrade mor expensive.

The final amount of power gained from an ECU remap varies between models. Some cars may gain as little as 5% while some may gain as much as 40%, but expected increases in the engine’s power would be around 15-20%. The extra torque means fuel economy can improve but this varies even more, mainly depending on driving style and how much throttle is used.