Fuel injectors are told by a computer to deliver more fuel for cold starting and heavy loads like hills or accelerating. On light loads, the fuel injector can be commanded to deliver less fuel or even shut completely off when coasting downhill. Fuel injected cars typically have an electric fuel pump, an inline fuel filter, and a fuel pressure regulator in the system to deliver and precisely control all the fuel that may be demanded. Maintenance can include cleaning the fuel injectors and replacing the fuel filters in the fuel line or in the fuel tank. Use GM Fuel System Treatment, part number 12345104.
Shock absorbers cushion road vibration and bumps.
Located in the suspension near each wheel, they are connected to the wheel and the car frame. A different kind of shock, called the McPherson Strut, takes up less room and improves handling by combining the springs and shocks into one unit. When shocks and struts are worn, they can leak oil. Shock and strut wear can cause the vehicle to bounce up and down for too long after you hit a bump and cause tire and suspension wear. Both are terms for transmissions that transfer the power from the engine to the axles.