Engine tune up: Engine Control Unit (ECU) remapping

Back in the era of carburettors it was fairly easy to attack the engine bay with a spanner to extract more performance out of the engine. Times have moved on and due to technological advancements all cars today come with an Engine Control Unit (ECU) also known as a Power-train Control Module (PCM). It is an onboard computer that times and calculates fuel delivery, spark plug ignition, valve timing and a host of other functions depending on what the engine is equipped with. As a result, there is no use in trying to toggle the engine bay with a spanner to extract more performance out of a car, no good will come out of it. 

If you want to tune your car for fuel efficiency or enhanced performance you have to reprogram the ECU. There are two ways in which this can be done. One, by taking your car to a company that does ECU remapping for cars. They have different types of ECU remaps for different cars. They can tune it up according to the level you want it to, for performance or fuel efficiency. The second type of ECU upgrade can be done by a person at home. You have to buy the ECU remapping kit from a company that does ECU remapping. The remap unit can be connected to a computer and the ECU settings of a particular car have to be downloaded onto your computer hard drive and stored in the remap unit. The remap unit then has to be connected to the car and the ECU settings from the car will be downloaded onto the hard drive, which has to be emailed to the same ECU remapping company. The company will then e-mail you the ideal ECU remap setting for your car according to your needs. This setting can then be installed onto the computer of your car by connecting the remap unit to your car.

The second option is suitable for marginal ECU remapping which the car is capable of handling in terms of performance upgrade or fuel efficiency. Manufacturers program the ECU with a big margin for error in different conditions so that their cars do not turn out to be unreliable in adverse temperatures, bad conditions, etc. It is within this limit that the ECU can be remapped to take advantage of the system and make the vehicle perform better in certain conditions. 

The first option of taking your car to an ECU remapping company is ideal when a serious upgrade for performance is desired. A mere ECU remap is not enough or recommended for a major jump in performance. When an engine is tuned for a lot more power many engine components like valves, pistons, camshafts, etc go through added stress and strain which will wear these parts out faster. For a major performance upgrade various engine components have to be changed and performance parts have to be installed before a ECU remap is installed in the car’s onboard computer. 

ECU remapping companies know best about how much of a performance upgrade a stock engine can take and what mechanical components need to be upgraded for a particular engine remap or performance upgrade. With a performance ECU remap service intervals for the car will shorten depending on the level of an upgrade. 

The ECU on some cars are not easily reprogrammable. Manufacturers can lock their map onto the firmware, they can be made non-reprogrammable. A device called a Piggy back ECU comes to the rescue in these cases. Piggy back ECUs can fool the standard ECU into forcing a more aggressive timing by changing sensor settings and crank position. Some piggy back ECUs perform their own calculations and take control of some aspects of engine management like turbo wastegate control and ignition timing. Other types of piggy back ECUs will take the standard ECU’s timings and modify them and guess the next output a split second before it takes place. 

Piggy back ECUs are not recommended unless you have a deep understanding of ECUs and engine mechanics as these ECUs do not have knock protection. The trick is to set your timing conservatively and use high octane fuel. 

Benefits of Engine Control Unit (ECU) remap:

An engine remap is considered to produce greater power and torque. It also helps to flatten out initial hesitation in acceleration by increasing engine response in low revs, giving a more responsive and enjoyable drive. An engine control unit can also be remapped to return higher fuel economy.

The effects of ECU remap on different kinds of engines:

Naturally aspirated petrol engines

When a non-turbo charged petrol engine is remapped you can expect a 10 – 15 % increase in brake horse power (BHP) output depending on the remap. The engine will also produce up to 20% more torque through the rev range resulting in increased initial acceleration and lighter throttle responses at high speeds.

Turbo charged petrol engines

Depending on the engine remap a turbo petrol engine will develop 20 – 30% more brake horse power. The power will be spread thorughout the entire power band with power coming in quicker down the rev range negating lag and increasing engine responsiveness. Down shifting will become less needed in most situations. 

Turbo charged diesel engines

This is the high zone for engine remapping as a remapped turbo diesel can have a jump in brake horsepower output by as much as 50% and about 50 – 75% increase in torque depending on the engine specification. Engine responsiveness in all gears throughout the power band increases significantly.