Why Does My Car Jerk When I’m Stopped at a Red Light?

Engine Misfire

An engine misfire is one of the most frequent causes of a car jerking when it is idling. This happens when the fuel-air combination is not ignited at the proper moment in one or more of the engine's cylinders. Misfires may result from problems like:

• Faulty Spark Plugs: The engine may misfire and jerk as a result of worn-out or damaged spark plugs failing to provide the spark required to ignite the fuel.
• Ignition Coil Problems:The ignition coil sends the electrical signal to the spark plugs. If it’s faulty, it can cause inconsistent firing, leading to jerking.
• Dirty Fuel Injectors:If the fuel injectors are clogged or dirty, they may not deliver the right amount of fuel to the engine, causing a misfire.

Typical Repair Processes

The repair process for wheel well rust can vary depending on the extent of the damage:

• Rust Removal and Repainting:For minor surface rust, the area can be sanded down, treated with a rust converter, and repainted to match the rest of the vehicle. This is the simplest and least expensive option.
• Body Filler and Repainting: If the rust is more severe but has not fully penetrated the metal, a body filler may be used to repair the damaged area. After filling and sanding, the area is repainted.
• Panel Replacement: In cases of severe rust where the metal is compromised, the best solution may be to replace the affected panel entirely. This involves cutting out the rusted section and welding in a new piece, followed by painting and sealing.

Transmission Issues

Transmission problems can also cause your car to jerk when stopped. In automatic vehicles, the transmission should smoothly shift to a neutral-like state when idling. However, issues such as:

• Low Transmission Fluid:Insufficient transmission fluid can cause rough idling and jerking as the transmission struggles to operate smoothly.
• Transmission Control Module Problems: The transmission control module regulates the shifting of gears. If it’s malfunctioning, it may cause improper gear engagement while idling.

Vacuum Leaks

A system of vacuum hoses controls many engine operations, including idle speed, in your car. When the engine runs unevenly due to a vacuum leak, it may jerk when stopped. Typical reasons for vacuum leaks include:

• Cracked or Disconnected Hoses: Over time, vacuum hoses can become brittle and crack, or they might come loose, leading to a leak.
• Faulty PCV Valve: The Positive Crankcase Ventilation (PCV) valve is part of the engine’s emissions system and can cause vacuum leaks if it’s not functioning properly.

Dirty or Faulty Idle Air Control Valve

The idle air control (IAC) valve regulates the amount of air that enters the engine while idling, ensuring the engine runs smoothly at a stop. If the IAC valve is dirty or malfunctioning, it may not allow the correct amount of air to enter, causing the engine to jerk or stall.

Fuel System Issues

Problems with the fuel system, such as a failing fuel pump or a clogged fuel filter, can lead to an inadequate fuel supply to the engine. This can cause the engine to struggle at idle, leading to jerking or rough running.

Engine Mount Problems

The engine mounts hold the engine in place and absorb vibrations. If an engine mount is worn out or broken, it may not effectively dampen the engine’s vibrations, causing the car to jerk or shake when idling.

Conclusion

To stop the problem from getting worse, it's crucial to have your automobile examined by a professional if it jerks while you're stopped at a red light. Our skilled technicians at MyMechanic Malaysia can identify and fix the underlying reason of your car's jerking, guaranteeing safe and smooth driving. We can assist you with any issue, be it a misfiring engine, a gearbox problem, or something else entirely. Get in touch with MyMechanic Malaysia right now to arrange an inspection and maintain the best possible state for your car.