How To Test The Fuel Injectors (2001-2003 2.0L SOHC Dodge/Plymouth Neon)

When an injector fails, it'll usually stop injecting fuel because of an internal electrical problem (such as a short-circuit or open-circuit problem).

Checking if this has happened in the 2001-2003 2.0L SOHC Dodge Neon is neither complicated nor difficult since all four injectors are easily accessible. In this tutorial, I'll show you how to do it step by step, and all you need is a multimeter.

NOTE: This tutorial only applies to the 2.0L SOHC engine (Single Overhead Camshaft).

You can find this tutorial in Spanish here: Cómo Probar Los Inyectores De Combustible (2001-2003 2.0L SOHC Neon) (at: autotecnico-online.com).

APPLIES TO: This tutorial applies to the following vehicles:

• 2.0L Dodge Neon: 2001, 2002, 2003.
• 2.0L Plymouth Neon: 2001, 2002, 2003.

Symptoms Of A Bad Fuel Injector

Fuel injector failures usually come in one of two flavors. One, they can have an internal short circuit or open circuit that makes them stop injecting fuel.

Two, they can get clogged and mess up how they spray (atomize) fuel into their cylinder. Unfortunately, regardless of the type of injector issue, engine performance is gonna suffer.

These are the most common symptoms you'll see when one fails:

• Rough idle.
• Lack of power.
• The engine hesitates when you accelerate under load.
• Cylinder misfire trouble codes:
  • P0300: Random Cylinder Misfire.
  • P0301: Misfire In Cylinder #1.
  • P0302: Misfire In Cylinder #2.
  • P0303: Misfire In Cylinder #3.
  • P0304: Misfire In Cylinder #4.

Although the main focus of the test I'm going to show you is to check the injector's internal winding for short or open circuits, I'll also give you with a specific diagnostic strategy to identify clogged fuel injectors. So don't worry, this tutorial is jam-packed with useful tips on how to find a bad or clogged fuel injector (see: How To Find The Bad Or Clogged Fuel Injector).

Checking The Resistance Of The Fuel Injectors

We're going to measure the resistance of the four injectors using a multimeter set to Ohms mode (Ω). The expected and correct result of this test is to obtain a resistance of 10 to 16 ohms (Ω) for each injector.

If the resistance isn't within this specification, you can conclude that the injector has an internal an electrical problem and that it's affecting engine performance.

NOTE: It's important to note that when performing this test, your Neon should be at room temperature; that is, the engine should be cold.

Let's get started:

1. 1

   Disconnect the fuel injectors from their electrical connectors.
   
   NOTE: To identify which cylinder the fuel injector belongs to, see the illustration above with the cylinder numbers for the 2.0L Neon.

2. 2

   Set the multimeter to Ohms (Ω) mode.

3. 3

   Measure the fuel injector's resistance across its two male terminals with the multimeter probes (see the illustration above).

4. 4

   Record the resistance value that your multimeter shows for the specific fuel injector you're testing.
   
   The illustration above will help you identify the cylinder number to which the fuel injector belongs.

5. 5

   Repeat steps 1 to 3 for the remaining fuel injectors.
   
   NOTE: The resistance specification for the 2.0L Neon is: 10 to 16 Ohms.

Let's find out what your specific multimeter test results mean:

CASE 1: All fuel injector resistances are within the specified value. This is the expected and correct result of the test, indicating that none of them have an internal short-circuit or open-circuit issue.

If you suspect a clogged fuel injector that the resistance test can't detect, go to the next section: How to Find the Bad or Clogged Fuel Injector.

CASE 2: One of the fuel injectors recorded a resistance value that isn't within the specification. This tells you that the fuel injector is faulty. Replace the fuel injector.

How To Find The Bad Or Clogged Fuel Injector

Diagnosing a cylinder misfire in your Neon isn't complicated as you might think. Sure, you'll need to run a few tests, but they're not difficult to do. In this section, I'll explain how to tackle this issue using basic, budget-friendly tools.

With your test results, you'll be able to determine whether the cylinder misfire is due to a bad or clogged injector or some other issue. The best part is that you can do all these tests yourself, no need to take your Neon to an automotive repair shop.

These are the steps of my test strategy:

1. First, find the 'dead' cylinder.
   • This is the most important first step. You can do this by connecting an automotive scan tool (or code reader) and reading the fault codes stored in your Neon's fuel injection computer's memory.
2. After identifying the 'dead' cylinder, make sure it's receiving spark.
   • It's important to check for spark using a spark tester.
     • You can find this test explained step-by-step here: How To Test The DIS Ignition Coil (Chrysler 2.0L, 2.4L) (at easyautodiagnostics.com).
   • Make sure that the dead cylinder's spark plug boot and the spark plug are NOT soaked (or swimming) in engine oil.
   • You should also remove the spark plugs and check for cracks or carbon tracks (this is VERY important).
     • Here's a real-life case study on carbon tracks and how they can cause cylinder misfire: Carbon Tracks Are A Common Cause Of Ignition Misfires (at: easyautodiagnostics.com).
3. If the 'dead' cylinder is getting spark, the next step is to make sure it has good compression.
   • After ensuring the 'dead' cylinder's spark plug wire is delivering spark, you need to check for a low compression issue.
   • This is one of the most overlooked tests when diagnosing a cylinder misfire or rough idle. You can find the test here:
     • How To Test The Engine Compression (Chrysler 2.0L, 2.4L).
4. If the 'dead' cylinder has spark and good compression, the next step is to test the fuel injector's activation signal with a Noid light.
   • If every test gives you the correct and expected result, the next step is to make sure the fuel injector is receiving its activation signal.
   • The following tutorial on how to use a Noid light explains how to check for the fuel injector activation signal: (I know this isn't the most detailed article on the topic, but it should give you an idea of what's involved).
     • How To Use A Noid Light And Where To Buy It (at: easyautodiagnostics.com)
5. If the 'dead' cylinder has spark, good compression, and the fuel injector is being activated; the next step is to swap the fuel injector.
   • If I find that I have a specific 'dead' cylinder and:
     1. The ignition system isn't behind the issue.
     2. The compression value of that cylinder is fine (compared to the rest of the cylinders).
     3. The fuel injector's resistance is fine and it's being activated by the fuel injection computer...
     4. I think the fuel injector is clogged, I then swap that fuel injector with an adjacent one.
     If the cylinder failure now follows that swap, I now know that the fuel injector is clogged (or faulty) and needs to be cleaned or replaced.

This list of tests may seem like a lot (and a little overwhelming) but they are all doable with basic, affordable tools.

The core idea is simple: rule out one issue at a time. That's right, it's about testing one component and, if the test tells you it's good, you move on to the next test on the list. This is precisely the strategy that a professional automotive technician follows in the shop, and now that you know the process, you can do it yourself.