What Causes an Engine Misfire?

Hi we’ve had some questions lately about engine misfires like “What causes an Engine Misfire?” and “Can I drive my car with a Misfire?” or is an Engine Misfire serious?” We’re going to try to answer that for you today. Welcome to Mercie J auto care, where compassion and craftsmanship come together. I am Rick Smith, master certified technician. A misfire is basically one of the cylinders or multiple cylinders on your car that either is not producing power all the time or occasionally isn’t producing power. Now can you drive the car with a misfire? You can, but you risk damaging the catalytic converter. What causes an Engine Misfire? There’s a ton of things that can cause it, but I thought I’d give you do-it-yourselfer a little tip here. We can either have a misfire due to a fuel issue, due to an electrical or spark issue or due to an engine issue. Now the first thing we want to determine: Is it engine or is it fuel or electrical? The simplest way to do that is with a vacuum gauge, they’re pretty inexpensive. You just hook it up to main vacuum port on the intake manifold. As you can see this one is running about 15 to 16 inches of vacuum. If I shut the air conditioning off, it’ll go up to about 18. These are normal readings on a four-cylinder engine like this Ford escape. If this needle is bouncing, then we have an engine problem causing the misfire. This car is not misfiring but if it was and my needle is steady like this then it would have to be either the spark or the fuel. So I hope this has been a little informational to you thanks for watching until next time blessings to you and safe travels!