Common Engine Misfire Causes
So, now when you might suspect that your engine is misfiring, where should you start looking for the problem? Well, from my over ten years of experience in cars, here are the most common causes of engine misfires: Ranked from the most common to the least common.
1. Bad ignition coil/distributor if you have an old car
The entirely most common problem when it comes to misfires is the ignition coil. Some vehicles have a separate ignition coil on each spark plug, while some cars have one coil with a spark cable to each spark plug. Older cars do have a distributor and in some cases also an ignition coil. If you have separated spark plugs, unplug each coil to see if you can find out if any cylinders are not responding. Replace if you find one faulty or have a trouble code stored for one ignition coil.
2. Bad Spark plug
The second most common cause of a misfire is bad spark plugs. The spark plugs are firing up your cylinders, and they can get worn over time. Spark plugs are often very cheap and in most cases easy to replace. If you can’t remember the last time you replaced your spark plugs, it’s probably time to replace them. If you want to learn a bit more about spark plugs check this out: Spark Plugs symptoms.
3. Intake Manifold gasket leaks
Intake leaks near the cylinder heads are also very common when it comes to spark plugs. This problem was a lot more common in older cars without steel gaskets for the intake. So, if you have an older engine, you might want to check this. If you have a newer car, check for any other signs of leaks around the intake manifold gasket or the intake. Check for broken vacuum hoses.
4. 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.
5. Injector problem
Another problem which was more common five years ago was the injector problems. A faulty fuel injector will cause your engine to misfire, and these can be pretty difficult to diagnose without flow testing them. Injector problems are not very common on newer cars, and because of this, you want to check out the other possible causes first.
6. Low compression/damage inside the engine
If you have checked everything else, it’s most likely that you have low compression or other damages inside of your engine. A faulty timing belt could also cause low compression and you want to make sure this one is correct first. If you’re going to learn a bit more about how to check this, scroll down in the article, and you will find more information about it.