A brief history on performance chips; they became popular in the '90s with dramatic advancements in the electronic and software engine management, manufacturers installed small, read-only chip modules that contained preset values controlling spark timing, fuel injection, throttle control, and boost control (for turbocharged engines).
- Spark ignition - they tell sparks when to light up
- Fuel injection - without it, injectors would not “know” how to inject fuel at just the right moment (and how much of it)
- Throttle control - values that say just how much throttle valve will open at a certain point in time in the chip module control
- Boost control - they tell the turbocharger how much it can spool up and how much boost should it produce
With that said, it is safe to assume that back in the '90s and for some cars in the early 2000s, performance chip modules were like the brain of the engine. Now, with slight changes in the preset values, aftermarket specialists developed performance chips so that they release hidden engine potential - more power. After some parameters are changed, all the installed hardware will start to behave differently. In simplest of terms, performance chips would allow a bit richer fuel mixture, slightly change ignition timing, and slightly alter change throttle response. Resulting in about 10-20 more horsepower, maybe more for turbo-diesel engines.
Today, however, performance chips are no more. Performance chips are replaced by what can only be described as computers. Welcome, the age of the Engine Control Unit (ECU).
You might still wonder why manufacturers do not do this in the factory? Well, original software is usually perfectly programmed to provide the optimum balance between performance, power and engine wear. What Performance chip tuning (or ECU flash) does is put more stress on all the elements. Tuning the engine this way would probably void the warranty. Now, I could go into great details describing how wear and tear actually occurs, but TL;DR it means a shorter lifespan. However, if you do it right and do not go for power overkill, you can avoid major engine problems.