How to diagnose an engine misfire

How to diagnose an engine misfire. Welcome to Mercie J Auto Care , where compassion and craftsmanship come together, I'm Rick Smith. So first of all, when we go to diagnose a misfire it can be helpful sometimes to just pull the codes because a P030_ like a P0301, P0302, P0303 etc. can help us know which cylinder is misfiring. We need three basic things for a cylinder to fire. We need good, healthy compression. So one of the things that you can do is if you listen carefully and you crank the engine over with either the fuel or the ignition disabled, it should crank smoothly and sound like, "Ni ni ni ni ni ni ni" but if you hear it go "Ni ni ni ni NI ni ni ni NI" then you probably have low compression on one of the cylinders. So if our compression is even and healthy, the next thing we have to have is we need to have healthy Spark. So you're going to have to find a way to check that, that varies from car to car. Then the third thing we need is fuel. So first of all, we have to have fuel pressure and the right amount of it. Then secondly, we have to have our injector squirting the right amount. Little trick on an injector, if you have a long screwdriver and the injectors accessible, with the car running you can put the screwdriver on it and you should hear the injector clicking. Fuel pressure, you have to look at some other ways of how you might need to check that. Then lastly if the misfires only at idle as opposed to while you're cruising you might want to look for a vacuum leak. I know this hasn't been real specific but I hope the information has been helpful to you and until next time, safe travels and blessings to you.