How to Test the Fuel Injectors
(Dodge, Jeep 4.7L V8)

How to Test the Fuel Injectors (Chrysler, Jeep, Dodge 4.7L)

In this this tutorial, I'll show you one of the ways to test for a BAD fuel injector by doing a fuel injector resistance test.

Since the 4.7L V8 engine is equipped with 8 fuel injectors, I'll also show you a specific diagnostic strategy you can use to find the or BAD fuel injectors.

Here are the contents of this article at a quick glance:

  1. Symptoms of a BAD Fuel Injector.
  2. What Tools do I Need to Test the Fuel Injectors?
  3. The Fuel Injector Test.
  4. Interpreting the Results of the Fuel Injector Test.
  5. Should I Test all of the Fuel Injectors?
  6. My Personal Testing Suggestions
  7. Where to Buy the Fuel Injector and Save

Symptoms of a BAD Fuel Injector

The three most common ways that a fuel injector fails are:

  1. The fuel injector fries internally and won't spray any fuel.
  2. The fuel injector gets clogged with deposits and won't spray enough fuel or in the proper spray pattern.
  3. The fuel injector doesn't activate (spray) because it's missing power or it's switching signal and won't inject fuel at all.

No matter what the root cause, a BAD fuel injector will cause the engine to idle rough and miss when you accelerate it down the road.

What throws a ‘wrench into the works’... is that the PCM won't always set a specific fuel injector trouble code. But if it does, you'll see one of the following:

  1. P0201: Injector #1 Control Circuit.    P0205: Injector #5 Control Circuit.
  2. P0202: Injector #2 Control Circuit.    P0206: Injector #6 Control Circuit.
  3. P0203: Injector #3 Control Circuit.    P0207: Injector #7 Control Circuit.
  4. P0204: Injector #4 Control Circuit.    P0208: Injector #8 Control Circuit.

From personal experience... I can tell you that around 90% of the time, when you do have a BAD fuel injector, you'll see a misfire trouble code:

  1. P0301: Cylinder #1 Misfire.   P0305: Cylinder #5 Misfire.
  2. P0302: Cylinder #2 Misfire.   P0306: Cylinder #6 Misfire.
  3. P0303: Cylinder #3 Misfire.   P0307: Cylinder #7 Misfire.
  4. P0304: Cylinder #4 Misfire.   P0308: Cylinder #8 Misfire.

And well... the other symptoms your vehicle may experience are:

  1. Lack of power.
  2. BAD gas mileage.
  3. Check engine light (CEL) is on.

What Tools do I Need to Test the Fuel Injectors?

To do a fuel injector resistance test, you don't need a whole lot of stuff, since the most important tool you'll need is a multimeter (which can either be an analog multimeter or a digital multimeter).

Here's a basic list of tools you'll need:

  1. A Multimeter.
    1. You'll only be using the multimeter to check resistance (Ohms).
    2. If you need to upgrade or buy a multimeter, check out my recommendation: Buying a Digital Multimeter for Automotive Diagnostic Testing (found at: easyautodiagnostics.com).
  2. Scan Tool.
    1. To actually test the fuel injectors, you don't need a scan tool (since a scan tool can't dynamically test the fuel injectors). But, having one makes the whole process easier... since you're able to retrieve any diagnostic trouble codes (DTCs) stored in the PCM memory.
    2. Don't have one?... check out my recommendation: Abe's Scan Tool Recommendation.
  3. Pen and Paper to write down your fuel injector resistance test results.

The Fuel Injector Test

There's a good chance that you already have one (or several) specific fuel injector you want to test or you don't know where to start...

If you want to test just one fuel injector or several, this will be your starting point. If you don't know where to start, I suggest you do a cylinder balance test to find out which cylinder is the one that's ‘dead’ and could possibly have a BAD fuel injector.

If possible, do the fuel injector resistance test with a slightly warmed up. If your Dodge or Jeep SUV or pickup has been running for a while and it's hot, let it cool down for about an hour. If it's completely cold... crank up the engine and let it warm up for about 20 minutes.

Although having the engine warmed up helps to get a more accurate snapshot of the condition of the fuel injectors, it's not that critical...

...So, if you have already removed the fuel injector or fuel injectors, or the vehicle Cranks but Does Not Start, etc., you don't have to install the fuel injectors and start the engine to warm her up. You can test them cold (and off of the vehicle).

Alright, here are the steps:

  1. 1

    Unplug the fuel injector from its electrical connector.

    1. Disconnect the one that you suspect is BAD and at least 2 others.
    2. You can test all of the fuel injectors if you want or need.
  2. 2

    Place your multimeter Ohms mode.

    1. You'll be measuring the internal resistance of the fuel injectors in a few moments.

Continued in the next page.



Chrysler Vehicles:

  • Aspen 4.7L
    • 2007

Dodge Vehicles:

  • Dakota 4.7L
    • 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007
  • Durango 4.7L
    • 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007

Dodge Vehicles:

  • 1500 Ram Pickup 4.7L
    • 2002, 2003, 2004, 2005, 2006, 2007

Jeep Vehicles:

  • Commander 4.7L
    • 2006, 2007
  • Grand Cherokee 4.7L
    • 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007

Mitsubishi Vehicles:

  • Raider 4.7L
    • 2006, 2007

“I never made a mistake in my life. I thought I did once, but I was wrong.”
Charles M. Schulz

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