How To Find The BAD Or Clogged Fuel Injector

What makes diagnosing a defective fuel injector a challenge, on the 2.7L V6 engine, is the fact that to access them you need to remove the intake manifold plenum.

The cool thing is that there's a logical step-by-step way of finding out if a fuel injector is really causing a misfire.

So, what I've always done, is to first eliminate the ignition system as the cause of the problem. Then I've tested engine compression.

Here's the diagnostic strategy that I used:

  1. Find the ‘dead’ cylinder first.
    1. This is accomplished by checking for misfire trouble codes (P0301, P0302, P0303, P0304, P0305, P0306) with a scan tool or code reader.
    2. If no misfire trouble codes are found, and the engine is misfiring, then you need to do a cylinder balance test.
  2. Once the ‘dead’ cylinder has been identified, the next step is to make sure it's getting spark.
    1. This test simple involves checking that the dead cylinder's ignition coil is firing off spark. It's important to perform this test with a dedicated spark tester.
    2. It's important that you check that the spark plug boot and spark plug wire are not damaged, cut, or burned.
    3. You should also remove the spark plug and check it for cracks or carbon tracks (this is SO important).
      1. 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 that cylinder has good compression.
    1. This is one of the most overlooked tests when diagnosing a misfire or rough idle condition. You can find the test here:
      1. How To Test Engine Compression (2.7L V6 Chrysler).
  4. Check the ‘dead’ cylinder's fuel injector's internal resistance.
    1. This now involves removing the upper intake manifold plenum to access all of the fuel injectors.
  5. Swap the fuel injector 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... I now know that fuel injector is clogged (or bad) and needs to be cleaned or replaced.

The most important thing to remember is to first identify the misfiring cylinder. Once you've identified it, keep in mind that either air, spark or fuel is missing and keeping that cylinder from producing power.

Here's a real life case study on how to find the defective fuel injector that may help: How To Find a BAD Fuel Injector (Case Study) (at: troubleshootmyvehicle.com). Although all of the steps won't apply to the 2.7L V6 engine in your Dodge Stratus (or Chrysler Sebring), it'll help you see the diagnostic strategy that I used to find the bad fuel injector.

Precautions To Take When Removing The Intake Manifold Plenum

Precautions To Take When Removing The Intake Manifold Plenum. How To Test The Fuel Injectors (2001-2003 2.7L Dodge Stratus And Chrysler Sebring)

The only thing that complicates testing the fuel injectors on the 2.7L V6 engine is that the intake manifold plenum has to be removed to access them.

Removing the upper intake manifold plenum is a pretty straight-forward process. As you're removing it, keep in mind the following precautions:

  1. Buy or borrow a repair manual (preferably a Haynes Repair Manual -Chilton manuals suck) so that you can have the intake manifold removal process explained in detail.
    1. The manual will also give you the torque specifications for the bolts.
  2. Be careful that no foreign object, like a bolt, a nut, or any metal piece/part, falls into the open manifold port runners.
  3. Once the plenum has been removed, place a clean shop towels on the open intake runners. This will keep things from falling into them.
  4. As you're removing bolts, nuts and stuff from the intake plenum to remove it, place them in a container and away from the engine compartment.

I can tell you from personal experience that if anything falls into the open intake manifold runners and you start the engine, it's gonna' sound like someone is beating the engine with a sledge hammer.

The only way to remove what fell in, and to see the damage to the piston and cylinder head valves, is to remove the cylinder head. So be alert and be careful.

When your testing is done and you're installing the plenum, don't use any type of gasket sealer on the gaskets (like RTV Silicone). Install the gaskets dry (without any adhesive). This will help you avoid vacuum leaks down the road.

Removing the plenum is not an out of this world thing that no one can do, it's done around the country in many shops without complications or unhappy endings by simply following some precautions.

Where To Buy The Fuel Injector And Save

The following links will help you comparison shop for the fuel injector on your 3.0L V6 Chrysler (Dodge or Plymouth):

Not sure if the above fuel injectors fit your particular 2.7L V6 equipped Stratus or Sebring? Don't worry, once you arrive at the site, they'll make sure it fits! If it doesn't, they'll find you the right one.

More 2.7L Dodge Tutorials

If this tutorial was helpful, you can find a complete list of 2.7L Dodge tutorials in this index:

  1. Chrysler 2.7L Index of Articles.

Here's a small sample of the tutorials you'll find in the index:

  1. How To Test The Blower Motor (2001-2006 Dodge Stratus).
  2. How To Test The Throttle Position Sensor (2.7L V6 Chrysler).
  3. How To Test The MAP Sensor (2000-2004 2.7L Chrysler).
  4. How To Test Engine Compression (2.7L V6 Chrysler).
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