Rough Running Bad Mileage How to Diagnose Car Truck Fuel Injectors

In this video, we're gonna be talking about fuel injectors and some different techniques on how to diagnose them. So your engine is running rough, you have a misfire. You probably have a check engine light flashing, and you've already diagnosed the fact that you have spark, your plug is good, your wire is good, and your coil is good. Now let's move on to the fuel injector.

Some older vehicles had something called TBI, which is throttle body injection, it injects the fuel right into the throttle body. New vehicles have something called direct injection where it injects the fuel directly into the combustion chamber. We're gonna go over something called multiport injection, which is right in the middle. This is...the majority of the vehicles out there have this. So we have pressurized fuel in a rail and it's gonna go through each individual injector into the intake runner, which is gonna go past the intake valve into the combustion chamber.

Here we have the fuel injector. Now you're gonna have high-pressure fuel that goes in this end, it goes down to here. There's gonna be an electromagnet in there, it's controlled by the PCM, the two wires and then a power and grounded. And that's gonna control this valve, that's gonna move in and out, and that's gonna give you the spray coming out this screen, and that's gonna atomize the fuel to make it work.

Here's an injector that's working. What if we have an injector that's not working? How do we determine where that injector is? Well, one way you could use a scan tool and figure out which cylinder is misfiring if it actually tells you that, or if there's a code for the injector if there's a break in the circuit that could tell you which injector it is. But also if you don't have either of those, when this valve opens and closes, it's gonna make a tapping noise.

So we can go around to each injector and check for a tapping noise. With the engine running, you can take the stethoscope and just place it on each individual injector just like that and compare the sounds. And when you find the injector that's not making any noise that's the one that you have to look into. Or you could take a tool like this and go around to each individual injector, place it on the injector. It's gonna measure the vibrations in the injector and let you know which one is not working.

Another way to test the injectors, you could check it with a multimeter. Check the resistance and put one lead on one side and one on the other. The problem with this is it's gonna be hard to find a spec for the injectors, you might be able to find one but it's not easy. So what you could do is compare it to the other injectors and then see if you have one that's skewed. Now, if you go to check the injector and it's completely open, that's good also, because then you can determine that it's bad, but you could still have an injector that has the correct readings but internally it is stuck and that would still not really give you a good determination whether the injector is good or bad.

Now you've determined which injector is not working, now why isn't it working? Is there something wrong with the injector or is it something wrong with the signal getting to the injector? Now we disconnected the connector. Now you want to look at the terminals to make sure they're not corroded, they look pretty good. Just check the wires right around there, make sure there's no broken wires. Sometimes some rodents will chew these wires, you'll have some mice or something but check those.

And what we're gonna do is use this noid light. Now this is specially made for checking injectors. It's calibrated properly so it's not gonna mess up any electronics or anything. And you get the right one that fits into the connector and we'll start the vehicle and just take a look. It should be pulsing. Since that was flashing now we know everything up to the injector is working, that injector is bad, but what if it wasn't flashing? What's your next step? There's probably something wrong with the PCM or ECM or something wrong with the power getting to the injector whether it be a fuse or a wire or a connector.

Some other things that can go wrong with an injector but they're still working mechanically, it's still getting its signal and it's still making noise, you could have a fuel injector that's leaking and excessive fuel is getting into the cylinder where it's gonna cause a rich condition, not as easy to diagnose. If you don't have the proper tools to diagnose, you could always swap injectors with another injector and determine that way. It could always be leaking externally then you'd be able to see it.

And also the O-ring could be leaking also. And sometimes those O-rings get old and dry up and they need to be replaced, you have to pull the injectors out to do those. You may also have a partially plugged up fuel injector that could be caused by dirt and debris or even carbon buildup, which if you catch it early enough you could use some type of fuel injection cleaner to save you from having to replace the injector. So now you know how to diagnose a fuel injector. I hope you enjoyed this video. If you did, make sure you subscribe to our channel, ring that bell, turn on all notifications so you don't miss any of our videos.

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