Why Does a Car Engine Misfire? 5 Reasons!

Misfires are a common problem in today's modern gasoline engines. Have you noticed if your car recently had a rough acceleration? Well, it may be a sign that your car misfires. It usually comes off as a sudden jerk coming from the engine. You can notice this when you are on high RPM's or in a higher gear. This is usually a common symptom of how an engine misfires. If you notice the engine is vibrating unusually, this can also be a sign.

Another common sign is having the check engine light illuminated. So, check your gauge cluster for this.

Here are some of the reasons why an engine misfires:

1. Bad Ignition Coil

Let's start off with the most common cause, a bad ignition coil. The ignition coil is a part of the vehicle's ignition system that is a component of the electronic engine management system. It functions as an induction coil. Because this component is mainly responsible for the engine to spark, the result is a noticeably decreased performance. Usually, this will give obvious symptoms that will alert the driver.

2. Intake manifold Gasket Leaks

Automobiles need oxygen too. Oxygen creates explosions inside the engine for the internals to move. The intake manifold is like the human lungs that provide oxygen to the engine. This part also transports coolant to the cylinders. Because this is usually made of rubber and plastic, it can get cracked or brittle. More importantly, this is a crucial part and any defect in it would further damage the engine. When this is damaged, the engine does not have enough air, gas, and coolant resulting in overheating.

Read our take on jump starting a car in case you face car battery dead problem. However, you can see similar type of symptoms due to the lack of transmission fluid. So, check that too.

3. Bad fuel injector

Modern cars have electronic fuel injection that sprays fuel into the engine. An engine control unit makes sure it delivers the right amount of fuel into the engine. Although they are unlikely to malfunction, they could get dirty over time and get clogged causing it to fail completely. This directly affects engine performance. When the fuel injectors go bad, the combustion process is obstructed causing a misfire to the engine. Low fuel economy and slow performance are often associated with this. It is best to fix this early on if it is diagnosed.

why does a car engine misfire

4. Low fuel pressure

It is often caused by a faulty fuel pressure regulator, clogged fuel filter or a defective fuel pump. When the car does not get enough fuel at the right time, it results in slow performance, stalling and engine sputtering at high speeds. A common symptom is an engine sputtering at high speeds because the fuel pump cannot provide a constant stream of gasoline.

5. Low compression

When air and gas are mixed together inside the engine internal combustion compression takes place. If there's low compression even in one cylinder, you will get a decreased performance and a misfire. Some causes why this happens are cracked cylinder walls, valve issues, decrepit timing belts, gasket issues and worn piston rings.

To check if there is low compression, use a compression gauge to know if it's really a low compression issue. If it is a low compression issue, check the valves, gasket, cylinders, and pistons as these are some common places that it originates. If there are cracks or damage in these areas, be ready as these are costly and lengthy to be fixed.

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