How To Test The Fuel Injectors (2001-2004 3.0L Ford Escape)

Precautions To Take When Removing The Plastic Intake Manifold Plenum

As mentioned at the beginning of this tutorial, the only thing that complicates doing a fuel injector resistance test is having to remove the plastic intake manifold plenum.

Now, removing it is not that hard, but you do have to take certain precautions. Here are my suggestions:

1. Buy or borrow a 3.0L Ford Escape repair manual for the specific removal process and for the tightening torque specifications of the plenum.
2. Disconnect the battery negative (-) terminal from the battery. This is to prevent the accidental cranking of the engine.
3. As you're removing the intake manifold plenum, do not place bolts or nuts or washers any where near the immediate work area. Place all removed parts (like nuts, bolts, brackets, etc) on your work table. If a bolt or nut or washer or any other piece of metal falls into an open lower intake manifold port, you may have to remove the cylinder heads to remove it before you crank and start the engine.
4. Once the plastic intake manifold plenum is removed, place clean rags (shop towels) into the 6 open ports of the lower intake manifold. This will prevent any foreign material (parts, nuts, bolts, etc) from falling into them as you test the 6 fuel injectors' resistance.
5. Do not re-use the intake manifold plenum rubber gaskets, use new ones. When installing the new ones, DO NOT coat them in any type of sealant or gasket glue. There's no need to use these products on the new gaskets or you may inadvertently create a vacuum leak down the road. If you don't know where to buy them, check the link for the plenum gaskets here: Where To Buy The Fuel Injector And Save.
6. If you find any broken fuel injector connectors (a very common problem on all Fords), you must replace them. A broken fuel injector pigtail connector will cause a false connection. This false connection will leading to a misfire condition and corresponding trouble code. If you don't know where to buy them, check the link for the fuel injector pigtail connector here: Where To Buy The Fuel Injector And Save.

How To Find The Bad Or Clogged Fuel Injector

Finding the exact cause behind your 3.0L Ford Escape's misfire (rough idle) isn't hard. But, if you're not sure if a bad or clogged fuel injector is behind the problem, the following testing suggestions will help you.

The troubleshooting strategy below, has helped to accurately diagnose a failed/clogged fuel injector about 95% of the time and this has meant saving time, frustration, and more importantly: money.

OK, below are the diagnostic steps I take when trying to diagnose a bad fuel injector:

1. Find the ‘dead’ cylinder first.
   • This is the most important first step. Identifying the misfiring cylinders simply involves connecting a scan tool (or code reader) and checking for specific misfire trouble codes.
2. Once the ‘dead cylinder’ is found, the next step is to check it's ignition coil is sparking..
   1. The most common type of failure causing a misfire is a failed ignition coil.
      • You can find a step-by-step guide on how to test the ignition coils here: How To Test The Ford Escape COP Coils (Troubleshooting A Misfire) (at: easyautodiagnostics.com).
   2. It's important that you check that the ignition coil's spark plug boot and spark plug are NOT soaked (or swimming) in engine oil.
   3. You should also remove the spark plugs and check them 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 (at: easyautodiagnostics.com).
3. If the ‘dead’ cylinder's ignition coil is sparking, then the next step is to check it's compression.
   1. Low engine compression in the ‘dead’ cylinder will cause a misfire. You can find the test here:
      • How To Test Engine Compression (3.0L Ford Escape).
4. Test the fuel injector.
   1. If I've found out that I have a specific ‘dead’ cylinder and that its:
      1. Ignition coil is creating/delivering spark.
      2. Compression is within specification (compared to the rest of the cylinders).
      3. Fuel injector resistance is good.
      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.

Finding the bad/clogged fuel injector can be a challenge on your 3.0L Ford Escape but it's doable. What will help you save a lot of time, money and frustration is to first find the ‘dead’ cylinder. Following the above diagnostic strategy has saved my lunch quite a few times and I think it'll help you too!