What the ECU does
The ECU is a small computer that reads sensors around the engine many times a second: air flow, throttle position, engine speed, coolant and air temperature, boost pressure and more. It then adjusts fuelling, ignition timing and boost to suit.
The decisions are driven by tables of numbers called maps. A fuel map, for example, says how much fuel to inject for a given engine speed and load. Manufacturers fill those maps with cautious, one-size-fits-all values so the same engine can be sold in every climate, run on every grade of fuel and survive poor servicing.
What a remap changes
A remap, sometimes still called chip tuning, edits those maps. A specialist reads the original software from the ECU, adjusts the relevant tables within safe limits for that specific engine, and writes the new file back. No new parts are fitted for a standard (stage 1) remap.
- Fuelling and injection quantity
- Ignition timing (petrol engines)
- Turbo boost pressure
- Torque and power limiters
- Throttle response (accelerator pedal mapping)
What you can expect
Across the 2063 engines in our catalogue, a stage 1 remap adds an average of 31 bhp and 62 Nm. Diesel engines usually show the larger torque gain, while turbocharged petrol engines tend to show the larger percentage power gain. Your own result depends on the engine and the condition of the vehicle, so treat all figures as indicative.
Many drivers notice the difference most in everyday driving: stronger acceleration from low revs, easier overtaking and less need to change gear.
Who a remap suits
A remap suits drivers who want more performance or easier driving from a healthy, regularly serviced car. It is less suitable for engines that already have unresolved faults, worn turbos or injectors, or a poor service history; a good tuner will check these first.
What a remap is not
A remap is not a plug-in box and it does not involve removing emissions equipment. We do not remove or defeat DPF, EGR or catalytic converters, which is illegal on road vehicles in the UK. See our guide on DPF and EGR faults for the lawful alternatives.
Questions
Is ECU remapping the same as chip tuning?
They describe the same idea. On older cars a physical chip was replaced; on modern cars the ECU is reprogrammed through the diagnostic port, which is usually called remapping.
Does a remap need new parts?
No. A stage 1 remap is software only, applied to a standard car.
Can a remap be undone?
Yes. The original software is saved before any change, so it can be written back.