The most common causes of engine misfires are: worn spark plugs, weak fuel injector, vacuum leak, worn valve seals, carbon tracking, and no voltage at the coil. Misfiring engines should be looked at as soon as possible, as the problem can worsen over time and damage internal components of the vehicle.
Engine Misfire Symptoms
There are several different symptoms that you can feel when it comes to engine misfiring;
1. Rough Acceleration
When a misfire occurs, you can feel it like a light or massive jerk coming from the engine. These misfires do often come under load from the engine, and you have the most load on the engine when you are accelerating on higher RPMs and higher gears. Rough acceleration is a typical sign of that your engine is misfiring.
2. Rough Idle
Sometimes the engine will misfire on Idle also, and your engine sensors will get faulty values, and the air-fuel mixture will get messed up. This can cause a very uneven idle which can jump up and down and the engine may also shut off on idle.
A car engine is very balanced from the factory and often with balance axles and different tricks to get as few vibrations from it as possible. When one cylinder is not firing correctly, the engine will get unbalanced, and this can cause heavy vibrations inside your cabin on acceleration or at idle.
4. Slow acceleration
As we discussed before, misfires can cause the O2 sensors to get faulty information and generate a too rich or too lean mixture. Too lean or too rich mixtures can cause lowered acceleration and even put your car into limp mode, which will cause the vehicle to not rev past 3500 rpm’s, and it will shut off the boost pressure from the turbocharger.
5. Engine sound changed
If you are a bit into cars, you have probably noticed that there is a difference in sound from different engines. V8 engines have a very different tone than a four-cylinder engine. If your 4-cylinder engine is misfiring on one cylinder, it may sound like a three-cylinder engine. If your cars sound is extraordinary strange, it’s most likely misfires that you could hear.
6. Low fuel pressure
Low fuel pressure could be caused by a faulty fuel pressure regulator, a defective fuel pump or a clogged fuel filter. Low fuel pressure will cause lean mixture in your engine which will result in misfires on all cylinders. If you have trouble codes for misfires on all cylinders, you do want to check your fuel pressure.