What Causes the Automatic Transmission Vehicle to Jerk and Shake During Start-Up?

[GarrettFitz]

Here are the specific reasons why an automatic transmission vehicle jerks and shakes during start-up: 1. Faulty Spark Plugs: Failed spark plugs can cause one or more cylinders to misfire, resulting in uneven power output and severe vehicle shaking. 2. Poor Coordination Between Throttle and Clutch: If the clutch is released too quickly, the vehicle may exhibit jerking movements. 3. Fuel Pump Malfunction: When the fuel pump fails, fuel injection becomes uneven. Fluctuating fuel injection amounts lead to inconsistent power output. 4. Cold Start: Insufficient fuel combustion reduces the vehicle's power. During a cold start, when fuel and lubricant temperatures are low, more throttle input is required to meet power demands. Over time, the spark plug gap widens, decreasing ignition energy and causing poor fuel atomization, which results in vehicle shaking.

[KylieFitz]

I think your automatic transmission car jerks when starting, most likely due to worn or aged clutch plates in the transmission. Having driven for many years, I've found that if the clutch is used for too long and the friction material is nearly worn out, it will slip and vibrate during starting and shifting, naturally causing the car body to shake. Another possibility is an issue with the engine ignition system, such as eroded spark plugs failing to ignite properly, leading to uneven power output and sudden jerks when accelerating. You should immediately check if the transmission oil pressure is too low or if there are impurities in the oil that haven't been filtered. I recommend first checking the dipstick—if the oil is too dark or low, it needs to be replaced. This kind of jerking is even more dangerous on highways, as it can easily cause loss of control and collisions when starting. Don't wait until an accident happens to fix it. It's best to have a professional shop inspect the entire drivetrain system.

[DiFinley]

Oh dear, an automatic transmission car shaking and jerking like this is really nerve-wracking to drive. I used to encounter this issue often—it felt like riding a rollercoaster. Most likely, it's due to a loose or rusted driveshaft joint or axle bearing, causing uneven power delivery during acceleration and making the car sway side to side. If the engine mount is worn out, the whole engine becomes unstable and shakes along with it. When driving, avoid stomping on the accelerator at startup; try pressing lightly a few times to see if the shaking is only noticeable at low RPMs—it’s worse on slippery roads. I remember once driving up a steep slope to the supermarket when the car started shaking and nearly rolled back—I quickly pulled over to check and fixed it by replacing the axle later. It’s best to schedule maintenance early, regularly lubricate the suspension system—safety first.

[Kennedy]

My old automatic transmission also had the issue of shaking during start-up, mostly due to the transmission fluid being too old and thin, failing to protect the clutch plates. I suggest you first check the fluid level; if it's low, try replacing it with new fluid—older cars often overlook this. Additionally, a dirty engine intake system, such as a clogged air filter, can cause insufficient airflow leading to unstable oil pressure. When parked, observe if the idle is smooth; if not, clean the throttle body. Regular maintenance saves big money—don't wait until it breaks to think about repairs.

[Humbert]

When the car body jerks and surges, I always check it myself first: after starting, listen for any buzzing sound from the transmission, and feel the steering wheel to determine the vibration location. If there's strong vibration underfoot, it might be a clutch failure. Issues with the engine fuel pump or uneven fuel injection can also cause this. Don't just rely on the warning light; try starting in neutral to see if it's smooth, and combine it with a slope test. If the fuel line is clogged or the ignition coil is aging, you'll need a technician to test the data with a diagnostic tool. For safety, test in an open area to avoid harming the car or people.

[MacLondon]

My neighbor's car had the same issue last year, shaking like an earthquake when starting and jerking forward, which was really scary. It might be due to tire imbalance or stuck brake discs, causing uneven power distribution. Frequent hard acceleration from a stop wears things out faster, so try driving more smoothly for a few weeks to see. If the suspension springs are fatigued and softened, the car will sway badly on bumpy roads. Replacing parts can fix it completely, but regular maintenance of the brake system and wheels will extend the car's lifespan.