What Causes the Car to Shake When Starting?
2 Answers
There are several reasons why a car may shake after starting: 1. Unstable oil pressure: Abnormal fuel pump pressure or incorrect readings and malfunction of the intake pressure sensor can cause the car to shake. Solution: Check the oil pressure and replace parts if necessary. 2. Aging engine components: Car shaking can also be related to worn engine mounts. Engine mounts act as the shock absorption system for the engine, absorbing minor vibrations during operation. If the engine mounts are faulty, these vibrations can transfer to the steering wheel and cabin, causing shaking at idle. Solution: Replace the parts. 3. Severe engine carbon buildup: The most common cause of car shaking is excessive carbon buildup on the throttle body or fuel injectors. When there is too much carbon inside the engine, the fuel sprayed by the injectors during a cold start can be largely absorbed by the carbon deposits, leading to an overly lean air-fuel mixture and making it difficult to start. Solution: Clean the fuel system and check if the idle control valve has carbon buildup; clean if necessary.
Engine vibration during startup is a common issue I've encountered frequently during my long career in auto repair. The most prevalent cause is problems with the engine ignition system, such as worn-out spark plugs or carbon buildup preventing proper ignition, leading to uneven cylinder operation. Fuel system issues are also common culprits, like clogged fuel injectors or insufficient fuel pump pressure causing uneven fuel delivery. Worn or broken engine mounts are another frequent cause, especially in older vehicles that exhibit strong vibrations upon startup. Vacuum leaks can also contribute, with symptoms often more noticeable during cold starts. I recommend first checking the spark plugs and fuel system. If the vibration is accompanied by unusual noises, seek professional diagnosis immediately - it's better to address minor issues before they escalate into major problems. Safety should always come first.
