ECU remap is a process of enhancing the electronic engine management system of a car by updating the software installed by the manufacturer. The ECU (electronic control unit) is updated with a different set of commands that help the engine produce more power and run more efficiently.
Car manufacturers mass produce engines for use in countries all over the world and this means they have to be designed to handle a range of different operating conditions, as well as different grades of fuel and various climates, but there are other pressures including the need to reduce harmful exhaust emissions. Manufacturers will often program the engine control unit so that the engine is able to passing the stringent emissions tests with a low emissions value, meaning the car will fit into a lower road tax and company car tax band, but this is not necessarily the best setting for that engine to run at its best in the real world.
This gives an engine tuner the chance to improve the efficiency of the engine by reprogramming the electronic control unit to make the most part of 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 better throttle response, generate even more power and torque,and even use less fuel.
Approximately any car that has an electronic engine management system can be given an ECU remap, and that applies to both petrol and diesel engines. Results can be different but an ECU remap will always produce the finest 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 fuelling adjustments.
Sometimes it’s possible to achieve significant power gains in naturally aspirated engines. Some manufacturers offer the same engine in various models with varying levels of power, and this is done by de-tuning the engine with a different ECU map. This makes it possible to remap the ECU to release the same level of power as the higher tuned version. An example of this is the 2.0-liter petrol engine set up in the Volkswagen Golf, which is a de-tuned version of the similar engine found in the Golf GTI.
Doing and installing an ECU remap is a comparatively simple task. Mainly new cars have a diagnostic port somewhere in the engine bay or dashboard that allows mechanics to download error codes from the ECU when the car is in for service, and this similar port can be used to upload the new ECU remap using a laptop or special tuning devices. Some older cars will need the original chip on the ECU to be replaced, which requires more technical expertise and can make the upgrade more expensive.
The real power gain from an ECU remap varies between models. Several engines may gain as little as 5% while some may gain as much as 40%, but typical increases in the power of the engine would be around 15-20%. The additional torque means fuel economy can improve but this varies even more, mainly depending on driving style and how much of that new power you feel like using.
An ECU remap is generally cost-effective ways of getting more power from your car, and on some mainstream models can cost only a few hundred dollars.