When you press the accelerator pedal, you expect the engine to rev and the car to accelerate. If your fuel delivery system, ignition components and exhaust system are all working properly, that’s what happens. However, even just one problem in any of the systems mentioned could lead to your car hesitating and bucking under acceleration, during deceleration, or at idle.
How this system works:
When you press the accelerator pedal, the fuel pump sends gasoline through the fuel filter, up the fuel line, and to the injectors. The injectors “atomize” the gas, and spray it into the injectors (atomization just means it turns it into a very fine mist). There, the spark plugs ignite the gasoline, which combusts, moving the pistons and turning the engine.
Gasoline combustion creates fumes (exhaust), which must be vented. This is done through a relatively complex network of components. Most of the exhaust is sent through the exhaust manifold, the catalytic converter, and then out the exhaust pipe. Along the way, some of it is recirculated and burned again (using the EGR valve), and oxygen sensors monitor the exhaust process for the right levels of contaminants.
Common reasons for why missing or low pick up happens:
- Clogged Fuel Filter: Over time and through normal use, your fuel filter will become dirty and clogged. When this happens, the flow of fuel to your engine diminishes, which can cause hesitation and bucking.
- Failing Fuel Pump: If your fuel pump begins to fail, it will not send the right amount of fuel to the engine. Note that pumps can exhibit intermittent problems for a long time before they fail completely.
- Failed Oxygen Sensor: If one of the oxygen sensors in your exhaust system has failed, the computer cannot monitor the emissions, and pressure may drop, creating hesitation and bucking.
- Clogged EGR Valve: The EGR valve is a crucial component in the exhaust system. If it becomes clogged with carbon, it won’t operate correctly, and your engine may spit, sputter or hesitate.
- Worn Out Spark Plugs and Wires: In order to combust gasoline correctly, your engine needs a steady spark and stream of electricity. This is provided by the spark plugs and wires. If they’re worn out, your engine may spit and sputter.
How important is this service?
You need reliable performance from your engine. Even if the hesitation and bucking doesn’t cause internal damage, it can be extremely disconcerting to drive while these symptoms are present. It can also compromise your safety on the road. Regular maintenance is the best way to protect against hesitation and bucking. Make sure you’re having the spark plugs, wires and fuel filter replaced regularly. You should also have any Check Engine light diagnosed immediately.