When a fuel injector on your 1.7L Honda Civic fails, its internal resistance changes drastically (due to the fact that its internal coil's windings have shorted together or have an open).
A fuel injector that has failed will cause the engine to misfire as it idles and as you accelerate it down the road.
Thankfully, testing the fuel injectors isn't hard and/or difficult since they can be tested by simply measuring their internal resistance (and comparing it to what the factory specification is) and I'll show you how in this tutorial.
Contents of this tutorial:
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You can find this tutorial in Spanish here: Cómo Probar Los Inyectores de Combustible (2001-2005 1.7L Honda Civic) (at: autotecnico-online.com).
APPLIES TO: This tutorial applies to the following vehicles:
- 1.7L Honda Civic (DX, EX, LX): 2001, 2002, 2003, 2004, 2005.
Symptoms Of A Bad Fuel Injector
A fuel injector, on your 1.7L Honda Civic, can fail in one of several ways. It either:
- Stops injecting fuel completely due to an internal short or open in its coil windings.
- It doesn't inject enough fuel because its clogged.
- It over injects due to electrical issues.
No matter how the fuel injector fails, the symptoms are pretty much the same ones. These symptoms are:
- Rough idle.
- Lack of power.
- Hesitation when you accelerate your Civic down the road.
- Misfire trouble codes (OBD II equipped only):
- P0300: Random Cylinder Misfire.
- P0301: Cylinder #1 Misfire.
- P0302: Cylinder #2 Misfire.
- P0303: Cylinder #3 Misfire.
- P0304: Cylinder #4 Misfire.
The focus of this tutorial is to see if the fuel injector's internal coil has failed (and thus causing the fuel injector to stop injecting fuel) but testing for a clogged injector isn't that much more complicated and I'll show you how in the next page.
Where To Buy The Fuel Injector And Save
Check out the following links and comparison shop the fuel injector on your Honda 1.7L Civic:
Disclosure: As an Amazon Associate, I earn from qualifying purchases. If my tutorials help you, using these links is an easy way to support the site at no extra cost to you. Thank you!
Not sure if the above fuel injectors fit your particular Civic? Don't worry, once you click on the links and arrive on the site, they'll make sure it fits! If it doesn't, they'll find you the right one.
Checking The Injector's Internal Resistance
To find out if the fuel injector's internal coil has a short or an open in its coil windings, the first thing we'll do is check its internal resistance.
Unfortunately, the Honda manual doesn't list a specific resistance specification for the fuel injectors (for the 1.7L Civic engine). We can still test them, but it'll require testing all 4 fuel injectors and then making sure that all 4 resistance values are similar.
Any fuel injector resistance that is radically different from the majority points to a fuel injector that has an open or a short in its internal coil winding.
It sounds complicated, but it isn't. This is a very easy test that can be accomplished with a simple multimeter. The multimeter will set to its Ohms (Ω) mode to check the injector's resistance.
NOTE: Don't have a multimeter or need to upgrade yours? Check out my recommendation: Tekpower TP8268 AC/DC Auto/Manual Range Digital Multimeter (Amazon affiliate link).
Alright, here are the steps:
- 1
Disconnect the fuel injectors from their harness connectors.
You'll need to remove the air cleaner assembly to get to the fuel injectors. - 2
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 in the image viewer). - 3
Write down the resistance value that your multimeter records for the specific fuel injector you're testing.
- 4
Repeat steps 1 through 3 on the remaining fuel injectors.
Let's find out what your specific multimeter Test results mean:
CASE 1: All fuel injectors registered the same resistance values. This confirms that the fuel injector your are testing is OK.
Here's why: If any one of the fuel injectors were bad, your multimeter would've registered a completely and totally different resistance value (for that fuel injector). Since your resistance (Ohms) Value were the same for all, this is an indication that the fuel injectors do not have an internal electrical fault.
CASE 2: One of the fuel injectors registered a completely different resistance value. This indicates that the fuel injector is bad. Replace the fuel injector.
How To Find The Bad Or Clogged Fuel Injector
Finding the bad or clogged fuel injector on your 1.7L Honda Civic may seem hard but it isn't.
In this section, I'll share with you a simple diagnostic strategy I've use for many years to find the fuel injector that's either clogged or fried (internally).
This are the fuel injector diagnostic test steps:
- Find the 'dead' cylinder first.
- This can easily be done by checking for misfire trouble codes with a scan tool (or code reader).
- You won't always have a specific bad fuel injector code, but you'll definitely have a misfire code.
- If no codes are present, then the next best thing to do is a cylinder balance test.
- A cylinder balance test is one of the most effective ways to find a dead cylinder. The following tutorial will help you do a cylinder balance test:
- Check the ignition system for spark.
- After finding the 'dead' cylinder, it's important to make sure that each ignition coil is sparking (delivering spark to the spark plug).
- The following tutorial will help you test the ignition coils:
- It's important that you check that the spark plug boot and spark plug are NOT soaked (or swimming) in engine oil.
- 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).
- Check engine compression.
- After making sure that the ignition coils and spark plugs are OK, you need to check for low engine compression.
- This is one of the most overlooked tests when diagnosing a misfire or rough idle condition. You can find the test here:
- Noid Light Test.
- If every test above checks out OK, then the next step is to do a fuel injector Noid Light test.
- The Noid light test will help you make sure that the fuel injector is being activated.
- The following Noid light article/tutorial may help you: How To Use A Noid Light And Where To Buy It (at: easyautodiagnostics.com -I know that this is not the most in-depth article on the subject, but it should give you an idea of what is involved..
- Swap the fuel injector with its neighbor on the fuel injector rail.
- I'll swap out that fuel injector with its neighbor if:
- I have confirmed the ignition system is not at fault.
- I have confirmed the cylinder's compression value is good (compared to the rest of the cylinders).
- I have confirmed the fuel injector resistance is good.
- I think the fuel injector is clogged.
- I'll swap out that fuel injector with its neighbor if:
The above testing strategy may seem like overkill or too difficult but it isn't. Most of the above tests can be done pretty fast and are not hard to do.
I can tell you from experience that the way to save yourself the frustration of replacing good parts, your vehicle doesn't need and that don't solve the problem, is testing everything. Thankfully, there's a test for just about anything on your Honda Civic!
More 1.7L Honda Civic Tutorials
You can find a complete list of 1.7L Honda Civic tutorials in this index:
Here's a small sample of the tutorials you'll find in the index:
- How To Test The Alternator (2001-2005 1.7L Honda Civic).
- How To Test The Ignition Coils (2001-2005 1.7L Honda Civic).
- How To Do A Cylinder Balance Test (2001-2005 1.7L Honda Civic).
- How To Test The TP Sensor (2001-2005 1.7L Honda Civic).
- How To Test Trouble Code P0141 (2001-2005 1.7L Honda Civic).
- How To Test Trouble Code P0135 (2001-2003 1.7L Honda Civic).
If this info saved the day, buy me a beer!
