How To Test The Fuel Injectors (1998-2000 2.4L Caravan And Voyager)

The fuel injectors on the 2.4L Caravan (Voyager) are located under the intake manifold plenum and may look tough to test. But you'll be surprised at how simple it actually is to test them.

In this tutorial, I'll guide you step-by-step. Even though the injectors are tucked beneath the intake manifold plenum, I'll show you an easy method to check their internal resistance and determine if they have a short-circuit or open-circuit problem.

You can find this tutorial in Spanish here: Cómo Probar Los Inyectores (1998-2000 2.4L Caravan y Voyager) (at: autotecnico-online.com).

APPLIES TO: This tutorial applies to the following vehicles:

• 2.4L Chrysler Voyager: 2000.
• 2.4L Dodge Caravan: 1998, 1999, 2000.
• 2.4L Plymouth Voyager: 1998, 1999, 2000.

You can find the fuel injector resistance test for the 1998-2000 2.4L Caravan and Voyager here:

• How To Test The Fuel Injectors (1996-1997 2.4L Caravan, Grand Caravan, Voyager, Grand Voyager)

Symptoms Of A Bad Fuel Injector

Fuel injectors typically fail in one of two ways: they either get clogged or have an electrical issue with their internal winding. Regardless of the cause, the symptoms are usually similar.

The most common symptoms you'll encounter are:

• Rough idle: When you roll to a stop, the engine idles rough (shakes) due to one or more injectors not spraying fuel evenly.
• Lack of power: A faulty fuel injector will cause changes to the air/fuel mixture and it'll feel like you're not getting the power you should when you step on the gas pedal.
• Engine hesitation under load: The engine struggles or hesitates when stepping on the gas pedal when one or more fuel injectors don't supply enough fuel.
• Cylinder misfire trouble codes: One or more of the following trouble codes will be stored in the fuel injection computer's memory:
  • P0300: Random Cylinder Misfire.
  • P0301: Misfire In Cylinder #1.
  • P0302: Misfire In Cylinder #2.
  • P0303: Misfire In Cylinder #3.
  • P0304: Misfire In Cylinder #4.
• Poor Fuel Economy: Even just one faulty fuel injector means the engine has to work harder, using more fuel.

While this tutorial mainly focuses on checking the internal winding of the fuel injectors, I also have a testing strategy to help you identify any clogged fuel injectors. You can find it here: How To Find The Bad Or Clogged Fuel Injector.

Checking The Resistance Of The Fuel Injectors

To check to see if the fuel injector has suffered some sort of internal electrical problem, we'll check the resistance of each one with a multimeter.

We're not going to test the fuel injectors directly (since this would require removing the intake manifold plenum to have access to them).

Instead, we'll test them from the fuel injector harness connector. The fuel injector harness connector is the one shown in photo 1, 2, and 3 in the image viewer above.

NOTE: All of the resistance tests are done on the fuel injector harness connector with male spade terminals.

Here are the test steps:

1. 1

   Place your multimeter in Ohms mode.

2. 2

   Disconnect the fuel injector harness from the engine wiring harness connector.
   
   NOTE: All tests are done on the fuel injector harness connector which has male spade terminals.

3. 3

   Probe terminals 1 and 10 with the multimeter test leads to test injector #1.
   
   Your multimeter should register approximately 12 Ohms.

4. 4

   Probe terminals 2 and 10 with the multimeter test leads to test injector #2.
   
   Your multimeter should register approximately 12 Ohms.

5. 5

   Probe terminals 3 and 10 with the multimeter test leads to test injector #3.
   
   Your multimeter should register approximately 12 Ohms.

6. 6

   Probe terminals 4 and 10 with the multimeter test leads to test injector #4.
   
   Your multimeter should register approximately 12 Ohms.

Let's examine your test results:

CASE 1: All fuel injector resistances are within the specified value. This is the expected and correct test result, and it tells you that none have an internal short-circuit or open-circuit problem.

If you suspect a clogged fuel injector (that the resistance test can't detect), proceed to the next section: How To Find The Faulty Or Clogged Fuel Injector.

CASE 2: One of the fuel injectors recorded a resistance value that's not within specification. This indicates that the fuel injector is faulty. Replace the fuel injector.

How To Find The Bad Or Clogged Fuel Injector

As I mentioned earlier, fuel injectors can fail in two main ways. Checking for internal electrical issues is pretty straightforward, as you've seen in the test steps above.

Where it gets challenging is diagnosing a clogged injector. In this section, I'll share the testing strategy I always use to identify a clogged injector.

Also, if you're stumped on where to begin diagnosing a cylinder misfire problem, this section will help you get started and find out its root cause.

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 minivan'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 Ignition Coil (2.4L Caravan, Grand Caravan, Voyager, Grand Voyager) (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:
     • Testing Engine Compression (1996-2007 2.4L Caravan, Grand Caravan, Voyager, Grand Voyager).
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.

The key thing to understand is that the tests listed above are all about process of elimination. You test one component, and if it's good, you move on to the next. Keep going until you find the one that tests bad —that's the part you'll need to replace to solve the problem. It's the same approach the technician at the shop would take, and now you can do it yourself.