How To Find A Bad Fuel Injector (Case Study)

Fuel Injector Noid Light Test

The next step in my troubleshooting/diagnostic was to make sure that the fuel injector for cylinder #2 was getting both power and an activation signal from the fuel injection computer.

This test is accomplished with a fuel injector Noid light, and this is what I did:

1. I unplugged injector #2 from its connector.
2. Connected the Noid light to the injector's connector.
3. Asked my buddy crank the Accord.
4. Observed the Noid light for it to flash ON and OFF (after all, the Noid light is just a 12 Volt light bulb with fuel injector metal spade terminals to connect to the injector connector).
5. Compared the intensity and frequency of the flashed to injector #1' connector.
   • Comparing the flashes to at least one or two other fuel injector connectors is important!

This test was passed with flying colors since the flashing of the Noid light for cylinder #2 was the same for cylinder #1 (remember, cylinder #1 is a good working cylinder).

Now, I was ready to give Charles a conclusive result: The fuel injector for #2 cylinder was bad and needed to be replaced!

Swap Out The Fuel Injector

I would have done one more test and that would have been to resistance test the fuel injector and compare that value to the others but I didn't take along my multimeter!

But, because I had identified the true misfiring cylinder (with a cylinder balance test) and eliminated:

1. The ignition system (mainly the distributor cap, spark plug wires, and spark plugs).
2. Low engine compression.
3. Electrical problem preventing power or the injector's activation signal from reaching the #2 injector.

I felt 100% confident the injector was bad.

So what happened next? Well, Charles had not returned the old engine yet (the core), so he just took one of the injectors from that, swapped it with the bad one. Cranked up the Accord and problem solved!

In Conclusion

Why Charles just didn't swap out the fuel injector to begin with, I don't know. Or since he had identified the wrong cylinder, maybe he had already replaced it, but since he was replacing the wrong one, it didn't solve the problem.

Now, all of this reading might give you the impression that it took all day to figure the problem out, but it didn't. I spent about 20 minutes doing all of the tests and coming to the conclusion that the #2 injector was bad. The reason I mention this to you is so that the tests don't appear difficult and/or intimidating.

The really cool thing about these Honda's with a 2.2L or 2.3L, is that everything is in plain sight and easily accessible! I love working on these old Honda's!

Well, hope this info helped you and if you need any more tutorial resources, check these out:

1. How To Test For A Bad Fuel Injector (Honda 2.2L, 2.3L).
2. How To Test Engine Compression (Honda 2.2L, 2.3L).
3. How To Troubleshoot A No Start (Honda 2.2L, 2.3L).
4. How To Test The Igniter, Ignition Coil Accord, Civic, CRV, and Odyssey (at: easyautodiagnostics.com).