Misfiring Spark Plugs

Diagnosing a misfiring spark plugs can be a very difficult task to complete. It depends entirely on the underlying cause. It also is easier to spot in a smaller engine like a 4 cylinder than a larger engine like an 8 cylinder. Losing 25% of your engine performance is more straightforward than 12.5%. Knowing what symptoms to spot helps lead to a root cause, which then helps to diagnose the problem. That turns into a solution. Sounds easy right? Not entirely.

First, you need to look at what symptoms your car is demonstrating. Is your car vibrating or shaking while idling or are you having troubles starting your car? Is your engine hesitating or do you have signs of poor acceleration? These are all signals of bad or misfiring spark plugs. Misfires cause the performance of your car to suffer as well as its fuel economy, emissions, and idle quality. If you have an emissions test run while showing these signs, you will fail because of the high amount of hydrocarbons (HC) in your exhaust. It is best to notice as soon as possible when you might have a problem.

Once you’ve recognized that you have a problem and have narrowed it down to a spark plug issue, you need to think about the underlying cause. There are 3 main origins for misfiring spark plugs. A loss of spark is anything that prevents the coil voltage from jumping the gap at the end of the spark plug. This is caused by worn or damaged spark plugs, bad plug wires, or a cracked distributor cap. If you have a weak coil, then all of your cylinders will be affected. Another cause is when the air-fuel mix is too far out of balance to ignite. A “lean misfire” is when there is not enough gas to burn. Here you have a dirty or clogged fuel injector, air leaks, low fuel pressure, a restricted filter, or a leaky pressure regulator. A “rich misfire” occurs when there is too much gas to burn. This can be caused by a plugged air filter, a leaking fuel pressure regulator, leaking injections, or too high of fuel pressure. Lastly, you could have a loss of compression. This arises when your cylinder loses most of its air/fuel mix before it can ignite. When loss of compression happens, you probably have a leaky or burned out exhaust valve or a blown head gasket.

Keep in mind that misfiring spark plugs can happen in 1 or more cylinders at the same time. They can also be symptoms for another issue like an ignition system, fuel system, emission symptom, or some other engine condition. Don’t worry about trying to figure out exactly which thing is causing your problems all by yourself! Go see ABQ Transmission & Auto Repair or call them yourself 505-296-8645 . They will diagnose what is causing your spark plugs to misfire and fix it right the first time.