It's rare for a Honda Civic fuel injector to go bad, but that doesn't mean it doesn't happen. The cool thing is that a fried fuel injector can be easily tested with a simple multimeter resistance test, and this article will show you how.
Contents of this tutorial:
WIRING DIAGRAMS:
- Fuel Injector Circuit Wiring Diagram (1995 1.6L Honda Civic).
- Fuel Injector Circuit Wiring Diagram (1996-1998 1.6L Honda Civic).
- Fuel Injector Circuit Wiring Diagram (1999-2000 1.6L Honda Civic).
- PGM-FI Main Relay Circuit Diagram (1996-1998 1.6L Honda Civic).
This ‘Honda Civic fuel injector resistance’ test guide covers all of the different models of the 1.6L Honda Civic and Civic del Sol 1996, 1997, 1998, 1999, and 2000.
Tools You'll Need:
- Multimeter
- Pen and Paper
You can find this tutorial in Spanish here: Cómo Probar Los Inyectores (1.6L Honda Civic) (at: autotecnico-online.com).
Symptoms Of A Bad Fuel Injector
As you're probably already aware, each of your Honda engine's 4 cylinders need 3 things to produce power: fuel, spark, and air (compression).
So, when a fuel injector stops injecting fuel, whichever cylinder that fuel injector belongs to will go ‘dead‘. A ‘dead’ cylinder will cause a misfire and you'll see one or more of the following:
- Rough idle condition.
- Misfire (hesitation) under load (which means: when you step on the accelerator pedal).
- Lack of power when accelerating your Honda.
- Bad gas mileage.
- Misfire codes (P0300, P0301, P0302, P0303, P0304) lighting up the check engine light (CEL).
So, what causes a fuel injector to go bad? It's usually just old age, although not always. Here are the most common types of fuel injector failures:
- Fuel injector has fried internally and has stopped injecting fuel.
- Fuel injector is clogged.
- Fuel injector stuck On all of the time (as soon as the key is turned On). This is usually due to a bad fuel injection computer.
- Fuel injector is not receiving power or its activation signal.
With the help of this in-depth tutorial, you should be able to diagnose a bad fuel injector.
START HERE: Troubleshooting A Bad Fuel Injector
There are three separate tests in this tutorial and I've designed them with the DIY'er (Do It Yourself'er) in mind.
This means that you'll be able to troubleshoot the problem without the use of expensive diagnostic equipment.
Here's a brief intro of all 3 tests:
- Identify the ‘dead’ cylinder first.
- This involves doing a manual cylinder balance test and which is explained in a step-by-step manner.
- TEST 1: Find the Dead Cylinder First.
- Resistance test the fuel injectors.
- After finding the ‘dead’ cylinder, the next step is to measure the resistance of the fuel injectors with a multimeter and then interpreting the test results.
- TEST 2: Measuring The Fuel Injector's Resistance.
- Swap the fuel injector with another on the fuel rail (if applicable).
- Depending on the test result you get in TEST 2, you'll swap out the fuel injector, of the dead cylinder, with its neighbor on the fuel injector rail.
- TEST 3: Swapping The Fuel Injector.
NOTE: You modify the above tests to suit your particular diagnostic needs. If you don't have much troubleshooting experience, then I recommend starting from TEST 1.
TEST 1: Find The Dead Cylinder First
There are quite a few things that can fail on your 1.6L Honda Civic and cause a misfire or a rough idle condition, among those possibilities is a bad fuel injector.
The absolute best way to find out if the misfire or rough idle is being caused by a fuel injector is to first identify the cylinder that's misfiring.
The fastest and easiest way to find the ‘dead’ cylinder is by doing a manual cylinder balance test and in this test section I'm gonna' show you how to do one.
Once you have identified the cylinder that's ‘dead’ (misfiring), it's gonna' be a hundred times easier to confirm if the misfire is really being caused by a bad or clogged fuel injector.
OK, this is what you need to do:
- 1
Remove all the metal retainer clips from all 4 fuel injector connectors (if applicable)
Depending on how old your 1.6L Honda Civic is, it may or may not have metal retainer clips on the fuel injector connectors. If your specific Civic doesn't have them, don't worry. Go on to the next step.
NOTE: Once you've removed the metal clips, make sure all of the connectors are connected to their fuel injectors before you start the next test. - 2
Start the engine and let it idle,
Let the engine run for about a minute or two just to let the idle stabilize (even if the engine idle is rough). - 3
Unplug the connector from fuel injector #1, while you observe the engine's idle.
What you're looking for, is to see if unplugging the connector (from the injector) makes the engine idle worse.
If the engine's idle DOES NOT get worse, when you unplug the injector's connector, then you've found a ‘dead’ cylinder. If the idle does get worse, the cylinder is active (not ‘dead’). - 4
Repeat step 3 on the remaining 3 fuel injectors.
Let's take a look at what your test results mean:
CASE 1: You found a ‘dead’ (misfiring) cylinder. The next step is now to find out if the cylinder is misfiring due to a fried fuel injector.
This means checking the internal resistance of the injector, that belongs to the dead cylinder, with your multimeter. Go to: TEST 2: Measuring The Fuel Injector's Resistance.
CASE 2: You DID NOT find a ‘dead’ (misfiring) cylinder. Repeat the test one more time.
If you still don't find a ‘dead’ cylinder with the manual cylinder balance test, then the rough idle condition that your Honda is experiencing is due a malfunction that's affecting all cylinders equally.
