Fuel injectors do exactly what their name suggests, they deliver fuel into an engine's combustion chambers to be burned. Fuel injectors can cause a whole host of problems that can lead to major engine damage, if not diagnosed and replaced or repaired as soon as possible. A dirty or faulty fuel injector can cause engine problems such as misfiring, hard starting, stalling and hesitation.
Note: Factory Audi S3 fuel injectors, supplies additional fuel for modified FSI engines to make more power. Specific Unitronic software will be needed to make them perform properly.