Different names, but they usually mean the same thing.
The term ‘chip tuning’ dates back to a time when the engine control unit had a separate memory chip containing the engine control program and its calibration maps. Back then, the chip had to be desoldered and reprogrammed with specialist equipment, or replaced with a new one.
That is no longer necessary today. On modern vehicles, new calibration maps or even the entire software can usually be loaded through the vehicle’s diagnostic port. This follows the same approach used by manufacturer workshops and allows precise, efficient optimisation of the calibration maps. In most cases, the ECU no longer needs to be removed or opened.
So how does it actually work?
To keep it simple: the engine control unit is essentially a computer running the engine control program. This program is called application software, or ASW. There is also basic software that handles drivers and communication, but we’ll leave that aside here.
The ASW reads the engine’s sensors and controls its actuators, such as the fuel injectors, ignition and much more. Using calibration maps, it decides, for example, how much torque is requested at a particular engine speed and accelerator pedal position.
The calibration maps are stored in a separate memory area in the ECU. This area is called CAL, short for calibration. Chip tuning involves modifying the maps in the CAL area to increase power and improve how smoothly the engine runs. No add-on modules, often called tuning boxes, are needed, because you are using and adapting the manufacturer’s own functions.
Some tuners say, ‘I do software.’ Technically, that is not quite accurate: in most cases, they adjust the calibration maps in CAL rather than the ASW. At vehicle manufacturers, this work is called calibration, and the people doing it are calibration engineers, also known as calibrators.
Good chip tuning involves more than just changing calibration maps, though. That is only one part of the job. Want to know how to spot a good tuner? Take a look at this article: Trust me, I’m an engineer.