How To Test The Fuel Injectors (Nissan 2.4L)

Which Fuel Injector Do I Test First? Or Do I Test All Of Them?

The biggest reason you should test all of the fuel injectors on your 2.4L Nissan Altima (Frontier, or Xterra), is that you'll get a clear idea of what the average resistance value of each fuel injector should be.

This becomes especially handy (knowing the average resistance of all the fuel injectors) if you don't have a repair manual with the fuel injector resistance specification.

Why does this test work? Well, it's because all fuel injectors have a specific internal resistance that can be measured in Ohms mode on a multimeter. When a fuel injector goes bad, it'll normally have a completely different resistance value than the other ones.

Therefore, the purpose of the test is to find the bad fuel injector by reading its resistance and comparing this reading to at least two other fuel injectors. And since no specific resistance specification is given to compare against, it's important to test them all to find out the average resistance value of them.

My Nissan Doesn't Start

It's next to impossible to have all four fuel injectors go bad and cause the engine not to start (unless someone put sugar in your gas tank and they are clogged, this does happen).

In this section, I'll explore some of the things you need to check to get to the bottom of this no-start problem.

Here are a few things you need to check:

1. Do a fuel injector Noid light test.
   • In this test, you insert a Noid light into the fuel injector's connector and then have someone crank the engine for you as you watch for the Noid light to blink ON and OFF.
   • If the Noid light flashes (blinks) ON and OFF, then you now know that the fuel injector is getting both power and Ground (in other words, it's being activated by the PCM).
   • If the Noid light does NOT flash ON and OFF, then you need to make sure that you have voltage in one wire and that the PCM is Grounding the other.
   • The following Noid light article/tutorial may help you: How To Use A Noid Light And Where To Buy It (at: easyautodiagnostics.com). This is not the most in-depth article on the subject, but it should give you an idea of what is involved.
2. Check for spark and fuel injector pulses (with a Noid light).
   • Performing these two tests on ALL of the 4 engine cylinders on your Nissan is important because if you don't have spark AND fuel injector pulses (as checked with a Noid light), then the crank sensor is bad.
3. Check fuel pump pressure.
   • If the fuel pump doesn't work and you spray starting fluid into the engine, IT WILL START.
   • This may make you think the fuel injectors are bad, when it's the fuel pump causing the no-start problem.

Fuel Injector Tutorial Summary

In this section, I want to give you some personal experience input, on how to diagnose a bad fuel injector on your 2.4L Nissan Frontier (or Altima or Xterra). These are my basic troubleshooting tests and I usually follow them in this order:

1. Check for misfire codes.
   • Unfortunately, the PCM usually doesn't set a specific bad fuel injector code, but when a fuel injector does go bad, you WILL see a misfire code.
   • This is when owning a scan tool comes in handy.
2. Check for spark.
   • I do this, to make sure that the COP ignition coil or spark plug wire is not bad and the cause of the misfire problem.
3. Check the condition of the spark plug(s).
   • I do this by removing the spark plug of the dead cylinder and check it for cracks and/or carbon tracks.
4. Check engine compression.
   • This is a fast and easy test but is so often overlooked.
   • You can find this test here: How To Test Engine Compression (Nissan 2.4L).
5. Check fuel injector resistance.

So, the gist of all of the above testing, is to eliminate all of the most common problem areas that can cause a miss (after all, when a fuel injector goes bad, you'll have an engine miss).

If everything checks out, and the internal resistance of the fuel injector is not within the average resistance value of the other 3, I now have the confidence to buy a new one.

More Nissan 2.4L Test Articles

You can find all of the Nissan 2.4L test articles here: Nissan 2.4L, 2.5L Index Of Articles.

Here's a sample of the tutorials you'll find in the Nissan 2.4L Index:

1. How To Test The Starter Motor (Nissan 2.4L -Frontier, Xterra).
2. How To Test Engine Compression (Nissan 2.4L).
3. How To Troubleshoot A Blown Head Gasket (Nissan 2.4L, 2.5L).
4. How To Test The Throttle Position Sensor (1996-1997 2.4L Altima) (at: easyautodiagnostics.com).
5. How To Test The Power Transistor 2.4L Nissan Frontier, Xterra (1998-2004) (at: easyautodiagnostics.com).