How would a ECU help your car?

Answer 1

The ECU is the Engine Control Unit this is the electronic box in the car that tells the engine, transmission, brakes, airbags, multiple sensors and many more moving pieces of the car what to do, when to do it, and for how long. Think of it as the brain, it tells the coils to fire the spark plugs that ignite the gas that moves the pistons that cranks the torque converter that turns the transmission that rotates the driveshaft that turns the axles that makes the wheels go round. Long story short, it makes the car go. If no ECU no go.