What makes testing the fuel injectors on the 4.6L Ford V8 engine easy, is the fact that they're very easy to get to (on other fuel injected V8 engines you have to do quite a bit of a tear down to get to them).
In this tutorial, I'm going to explain how to test each one with a simple multimeter resistance test. This test will tell us if the fuel injectors internal coil winding has shorted or not.
Contents of this tutorial:
NOTE: The following tutorials may be of help to test the fuel injectors on the Crown Victorias (Mercury Grand Marquis) not covered by this tutorial:
- How To Test The Fuel Injectors (1998 4.6L Crown Victoria).
- How To Test The Fuel Injectors (1999-2000 4.6L Crown Victoria).
Symptoms Of A Bad Fuel Injector
The most obvious symptom that a failed or clogged fuel injector will cause is a misfire condition, but it's not the only symptom you'll see. Here are the most common symptoms you'll see when a one fails:
- Rough idle.
- Lack of power.
- Hesitation when you accelerate your car down the road.
- If your 4.6L Ford Crown Victoria is equipped with the OBD II system, you'll see one of the following fuel injector trouble codes:
- P0201: Cylinder #1 Fuel Injector Control Circuit.
- P0202: Cylinder #2 Fuel Injector Control Circuit.
- P0203: Cylinder #3 Fuel Injector Control Circuit.
- P0204: Cylinder #4 Fuel Injector Control Circuit.
- P0205: Cylinder #5 Fuel Injector Control Circuit.
- P0206: Cylinder #6 Fuel Injector Control Circuit.
- P0207: Cylinder #7 Fuel Injector Control Circuit.
- P0208: Cylinder #8 Fuel Injector Control Circuit.
- If your 4.6L Ford Crown Victoria is equipped with the OBD II system, you'll see one of the following misfire trouble codes:
- P0300: Random Cylinder Misfire.
- P0301: Cylinder #1 Misfire.
- P0302: Cylinder #2 Misfire.
- P0303: Cylinder #3 Misfire.
- P0304: Cylinder #4 Misfire.
- P0305: Cylinder #5 Misfire.
- P0306: Cylinder #6 Misfire.
- P0307: Cylinder #7 Misfire.
- P0308: Cylinder #8 Misfire.
The test I'm gonna' show you, in the following section, deals primarily with shorted fuel injector coil windings. But, I'll also offer you a specific diagnostic strategy to find a clogged fuel injector (in the next page, heading: How To Find The Bad Or Clogged Fuel Injector)
Checking The Injector's Internal Resistance
You're going to need a multimeter to test the resistance of each fuel injector. Now, you don't need a really fancy multimeter. Even an analog multimeter will do. If you don't have one and need to buy one and don't want to spend an arm and a leg on it, check out my recommendation here: Buying A Digital Multimeter For Automotive Diagnostic Testing.
NOTE: The resistance specification for the fuel injectors on your 4.6L V8 are with a cold engine. So if the engine in your Crown Victoria (Grand Marquis) has been running for any length of time, let it cool down completely. The warmer/hotter the fuel injector is, the more the resistance value will differ from the one given in the specification.
These are the test steps:
Disconnect the fuel injectors from their engine wiring harness connectors.
NOTE: To identify which cylinder the fuel injector belongs to, see the above illustration with the cylinder # id for the 4.6L Ford Crown Victoria (Mercury Grand Marquis).
Set your multimeter to Ohms (Ω) mode and:
Measure the resistance of the fuel injector across its two male spade terminals with the multimeter test leads (see the illustration above).
Write down the resistance value that your multimeter records for the specific fuel injector you're testing. The illustration above will help you identify the cylinder # the fuel injector belongs to.
Repeat steps 1 through 3 on the remaining fuel injectors.
NOTE: The fuel injector resistance specification is: 11 to 18 Ohms.
Let's find out what your specific multimeter test results mean:
CASE 1: One or more of the fuel injectors show a different resistance value than the one given in the specification (11 to 18 Ohms). This test result tells you that those fuel injectors, that don't have the indicated resistance value, have an internal problem with their coil winding. You will need to replace them.
CASE 2: All the fuel injector resistances are within the value given in the specification. This test result tells you that the fuel injectors don't have a problem with their internal coil winding. In other words, they're not shorted or have an open. There's still a good chance that the fuel injectors might be clogged. My suggestion to you is to go on to the next subheading: How To Find The Bad Or Clogged Fuel Injector.