How To Test The Fuel Injectors (2.4L Cobalt, HHR, Malibu, G5, G6, Solstice)

How To Find The Bad Or Clogged Fuel Injector

Trying to figure out if a fuel injector is defective or clogged can seem like a difficult thing to do.

The cool thing is that this type of problem is not that hard to troubleshoot especially if you have already tested all of the fuel injectors per the multimeter resistance test in the previous page.

If you suspect that a fuel injector is clogged (or defective) and you think it's behind a misfire problem, here are my suggestions:

1. Identify the 'dead' cylinder first.
   • You can easily accomplish this by checking for misfire trouble codes (P0301, P0302, P0303,P0304) or doing a cylinder balance test.
   • You can find the cylinder balance test explained here: How To Do A Cylinder Balance Test (2.4L Chevrolet Malibu).
2. Once the 'dead' cylinder has been identified, the next step is to make sure it's getting spark.
   • This means making sure that the ignition coil is sparking.
   • It's important that you check that the spark plug boot and spark plug are NOT soaked (or swimming) in engine oil.
   • You should also remove the spark plug and check it for cracks or carbon tracks (this is SO important).
   • Here's a real life case study on carbon tracks and how they can cause a misfire: Carbon Tracks Are A Common Cause Of Ignition Misfires.
3. If spark is present, then the next step is checking that the 'dead' cylinder has good compression.
   • The purpose of this test is to make sure that the 'dead' cylinder DOES NOT have low compression.
   • You can find the compression test explained here: How To Test Engine Compression (2.4L Chevrolet Malibu).
4. Perform a Noid light test on the fuel injector's electrical connector (of the 'dead' cylinder).
   • If every test above checks out OK, then the next step is to do a fuel injector Noid light test.
   • The Noid light test will help you make sure that the fuel injector is being activated.
   • The following Noid light article/tutorial may help you: How To Use A Noid Light And Where To Buy It (I know that this is not the most in-depth article on the subject, but it should give you an idea of what is involved).
5. Swap the fuel injector (of the 'dead' cylinder) with its neighbor on the fuel injector rail.
   1. If I've found out that I have a specific 'dead' cylinder and:
      1. The ignition system is not at fault.
      2. That cylinder's compression value is good (compared to the rest of the cylinders).
      3. The fuel injector resistance is good and...
      4. I think the fuel injector is clogged, I then swap out that fuel injector with its neighbor.
      If the misfire now follows that swap then I now know that fuel injector is clogged (or bad) and needs to be cleaned or replaced.

The above test are not hard to perform and you can find online tutorials for most of them. The above diagnostic strategy has saved my lunch quite a few times and I think it'll help you too!

More 2.4L GM Tutorials

You can find a complete list of 2.4L GM tutorials here: GM 2.4L Index Of Articles.

Here's a list of articles, you'll find there:

• How To Test The MAP Sensor (2008-2012 2.4L Chevrolet Malibu).
• How To Test For A Blown Head Gasket (2.4L Cobalt, HHR, Malibu, G5, G6, Solstice).
• How To Test Engine Compression (2.4L Cobalt, HHR, Malibu, G5, G6, Solstice).
• When Should I Replace The Spark Plugs (2.4L Cobalt, HHR, Malibu, G5, G6, Solstice).