What can cause an Engine Misfire?

What can cause an Engine Misfire? Welcome to Mercie J auto care where compassion and craftsmanship come together. I’m Rick Smith, master certified technician.

Now in order for a cylinder to fire, we need three things. We need a compression, which is engine mechanical issues. We need some fuel and then we need ignition or spark. So misfires can be caused on the spark side by ignition coils or spark plugs or wiring problems. On the fuel side, we just had an E 350 Ford van in and one of the fuel injectors was not spraying properly and so that caused a misfire because we didn’t have enough fuel there.

We could also have a vacuum leak that causes a misfire. We’ve had two European vehicles in here recently, an Audi and a Volkswagen and both had some mechanical problems with the valve train that was causing the valves to not function properly, and those caused misfires.

So misfires can be caused by some sort of a compression issue which is engine mechanical. It could be caused by a fuel issue, which could be a vacuum leak or an injector or some sort of fuel pressure issue. Thirdly, it can be caused by an ignition problem, which typically would be a spark plug or coil. Hope this informational to you until next time. Safe travels and blessings to you.