What Is An ECU?
An Electronic Control Unit (ECU) is also known as an Electronic Control Module (ECM) and there can be several different types of ECU’s fitted to a vehicle but the main four are:
- ABS ECU – Will control the Advanced Braking System of a vehicle.
- Gearbox ECU – Will control the functions of the Automatic Gearbox of a vehicle.
- Airbag ECU – Will control the Airbag system of a vehicle.
- Engine ECU – Will control the Engine parameters of a vehicle.
The key unit often referred to as the ECU of a car is the Engine ECU, also known as Engine Control Unit (ECU) or Engine Control Module (ECM) but also now known as Powertrain Control Module (PCM).
The ECU contains software and maps with set parameters to control how the engine will respond and how the vehicle will perform depending on the signal received back from the various sensors on the vehicle such as: Exhaust Emission Sensor, Exhaust Temperature Sensor, Intake Air Temperature Sensor, Mass Air Flow Sensor, Throttle Position Sensor, Fuel Rail Pressure Sensor, Coolant Temperature Sensor and so on.
With the signals back from all sensors, the ECU will process all information received to determine outputs such as: Amount of Fuel Injected, Injection Timing, Ignition Timing (Petrol), Timing Advance, EGR Position and so on.
Some ECU’s on later vehicles are Coded. A coded ECU will be locked the vehicle it is connected to and cannot be fitted to another vehicle without having it Re-Coded. Dealer-Level diagnostic equipment is required to recode an ECU but it is not always possible. Some ECU units can only be programmed once, so once coded to your vehicle it will be paired and locked to your vehicle for life.
Tuners / Remapping Specialists can utilize the maps of an Engine ECU (PCM) to increase the performance of a vehicle and in diesel vehicles increase the economy to make the vehicle more fuel efficient.
On older vehicles (pre-2000) tuners would have to “chip” the ECU by removing the factory fitted chip and installing an upgraded chip which would accept modified performance maps to increase the power output of the engine. This was known as chipping or chiptuning.
Newer vehicles (2000 onwards) are all fitted with an OBDII (On-Board Diagnostics) port. This OBD allows us to Remap (tune) an ECU without having to remove it or change any chips. This makes remapping much more safe & affordable and has opened up the market dramatically.
Some modern ECU’s have been manufactured with an Anti-Tuning chip (Tricore) to try and put a stop to the tuning market but leaders in the industry have been successful in bypassing the tuning software and successfully remapped Tricore ECU’s to increase Power, Performance & Fuel Economy.