Vehicle: 2013 Ford Fusion. Having a hard time diagnosing a Ford with a misfire? In this Diagnostic Quick Tip, National Field Trainer Jason Gabrenas shows a faster way to check Ford ignition coils using a lab scope to perform a Coil Current RFI Test.
Diagnosing ignition problems and misfires is a lot easier when you're using a lab scope.
In the scope there is a specific test just for Fords and testing their coils. It's called a Coil Current RFI Test. Let's walk through it right now.
We're in the Guided Component Tests right now and we're under the Fuel Injection System. It's an ignition test, so we'll go into Ignition Tests and. It is a secondary test and there it is, the Coil Current RFI Test.
The test is going to give us a little description about how we're doing. It says to set the amp probe up at the 20 amp setting.
Go down a little bit further, hook it around the coil on the battery, positive side, pull the coil out, flip it over, make sure it's not sparking on anything, and then hit view meter and the meter will come up. I'll go start the car and see what we get for a pattern.
Zoom out [on the screen] a little bit. Let's see if we can find the pattern there. So here's an example of a pretty good-looking pattern.
This is a fairly new car, so it doesn't have a lot of miles on it, and we would suspect it would be good.
We can scroll up in the background and take a look at what a good pattern is. That's a good wave form there, there's no weird RF spikes.
If we go down a little further there's an example of a bad pattern, and this the second little spike here, that's an RFI spike and we see some bad noise in there.
Really there aren't any noise artefacts in this pattern so this would be a good coil. A typically this is going to cause like a PL300 code, which is fairly common on a lot of these.
It's a good test to do. Nice and quick and easy, you don't really have to do much to tear it apart to get to it. So hopefully that'll help you out in your diagnostics.