Can a car misfire while idling?
Lily Fisher
Updated on May 12, 2026
A misfire will cause the engine to momentarily stumble, or lose rpms, and then regain its normal engine speed. The misfire will usually reappear, either under specific operating conditions or randomly. A misfire may occur when your engine is idling, causing a rough or uneven idle.
What causes misfire at idle only?
A dirty or damaged spark plug fails to create a spark. Likewise, bad wiring and cracked distributor caps can prevent spark plugs from operating correctly. Engine misfires may also stem from an incorrect air-to-fuel ratio. If the mixture contains too much air and too little fuel, it may fail to combust.What does a misfire feel like at idle?
Technically, a misfire is the result of incomplete combustion (or zero combustion) inside one or more of an engine's cylinders. But to you, the driver, the problem will usually feel like hesitation or shaking when the car is running. On modern vehicles, the check engine light will also pop on when there's a misfire.Why is my car sputtering when idling?
The most common reason your car engine is sputtering is because of an issue with the fuel system. This can be caused by a bad fuel filter, fuel pump, or fuel injector. It can also be caused by spark issues from bad spark plugs or ignition coils. While these are not all the possible causes, it's a good start.What are 3 common possible causes of a misfire?
The most common causes of misfires are worn, improperly installed, and mishandled spark plugs, malfunctioning ignition coils, carbon tracking, faulty spark plug wires and vacuum leaks.Symptoms Of A Car Misfiring While Driving
Do misfires go away?
Regardless of the specific cause, mechanical misfires are the most serious in regards to how they need to be addressed because they aren't merely going to go away in due time. Instead, they will likely fester and only worsen, leading to other engine damage if left untreated.Can a bad o2 sensor cause a misfire?
If an oxygen sensor or mass airflow sensor is failing, it could give incorrect data to your engine's computer, causing the misfire. When a vacuum line is broken, it can cause a fuel-injected motor to misfire.Why does my car shake when parked?
Motor mounts keep the engine attached to the car. If the vehicle shakes or the engine shudders a lot when stopped at a stoplight, or when parked with the engine idling, it might indicate the motor mounts or transmission mounts are damaged or broken. To see if this is really the problem, shift the car into neutral.Why does my car shake when stopped?
The most common reason your car is shaking when stopped or at idle is due to worn spark plugs or vacuum leaks. It can also be caused by loose or damaged engine mounts, a worn serpentine belt, a bad fuel pump, or any other fuel-related issues.Will a misfire always throw a code?
When there are no codes, but there is a misfire that would typically trigger a code, use your vehicle information database to determine what the enabling criteria for setting a code is. In the case of a misfire a P0300 (random or multiple cylinder misfire), or specific cylinder P0301-P0306 should have triggered.How can I tell if my engine is misfiring?
These are the signs of a misfiring engine that you need to look out for:
- The engine loses power.
- It is difficult to start the engine.
- Fuel consumption rises.
- Emissions increase.
- The engine makes popping sounds.
- The intake or exhaust manifold backfires.
- The engine jerks, vibrates or stalls.