TEST 2: Measuring The Fuel Injector's Resistance
If you've reached this point, it's because you've found which cylinder is the one that's ‘dead’ (misfiring).
The next step is to check the internal resistance of the fuel injector that belongs to the ‘dead’ cylinder and then compare that resistance value to the other 3 fuel injectors.
If you don't have a multimeter and need to buy one, check out my recommendations here:
- Buying A Digital Multimeter For Automotive Diagnostic Testing (at: easyautodiagnostics.com).
NOTE: To get an accurate test result, your Honda's engine should be warm. If your 1.6L Civic doesn't start, don't worry about the warm engine part.
Alright, here are the steps:
- 1
Disconnect all four fuel injector electrical connectors from the fuel injectors.
You may only need to test just one fuel injector, but I suggest you test them all. - 2
Set the multimeter in Ohms mode.
- 3
With the multimeter test leads, probe the first fuel injector's metal male spade terminals.
Make sure that the multimeter test leads don't touch. - 4
Write down the fuel injector's resistance your multimeter registers.
You'll be using this resistance value to compare it to the other three in a few moments.
You should also write down to what engine cylinder the fuel injector belongs to. You can use the image in the photo viewer as an aid in identifying the cylinders. - 5
You should see a fuel injector resistance value between 5 to 7 Ohms.
Don't worry if these resistance values don't match the value of each of the four fuel injectors on your Honda Civic (you'll see why below).
Alright, with the resistance values of all six fuel injectors on paper, let's interpret your results. Choose from one of the following CASES:
CASE 1: All of the multimeter resistance values are nearly identical. This means that the fuel injectors on your Honda Civic are OK.
The cause of the rough idle condition or a misfire condition or misfire codes, is not due to fried fuel injectors.
Here's why: When you do find one bad fuel injector, this one will register a totally different Ohms (resistance) value. And this will confirm beyond any doubt that that fuel injector is bad. So although this article doesn't give you a specific fuel injector resistance value for your 1.6L Honda Civic the fact that you tested them all and they are all registering the same resistance value, confirms the fuel injectors are not fried internally.
Your next step is to see if maybe the fuel injector is clogged. For this test, go to: TEST 3: Swapping The Fuel Injector.
CASE 2: One of the four multimeter resistance values is drastically different. This tells you that that particular fuel injector, on your Honda, with the drastically different resistance value is bad.
I suggest that you retest that fuel injector one more time to make sure of the Ohms (resistance) value. If this value is still the same as before, the fuel injector is bad.
TEST 3: Swapping The Fuel Injector
There are cases in which the fuel injector isn't fried internally and so it passes TEST 2 with flying colors. Yet the fuel injector is the one causing the cylinder to misfire.
This usually happens when the fuel injector is clogged and its spray pattern isn't atomizing the fuel correctly.
The best way to find out if this is happening is to swap the fuel injector of the ‘dead’ cylinder with its neighbor on the fuel injector rail.
NOTE: This test works and makes sense doing only if you have identified the ‘dead’ cylinder and have done TEST 2: Measuring The Fuel Injector's Resistance.
IMPORTANT: Take all necessary safety precautions, since you'll be working around fuel in this test step. Gasoline is extremely flammable. Thinks safety all of the time. If you have never removed/replaced a fuel injector before, consult your Honda's repair manual (no, not the owner's manual in the glove box!).
CAUTION: The fuel injector O-rings need to be replaced with new ones, whether the fuel injector is reused or a new one is installed. Once the fuel injector has been removed, it's O-rings must be replaced.
This is what you'll need to do:
- 1
Remove the fuel injector , of the cylinder that you found to be ‘dead’ when you did the manual cylinder balance test in TEST 1.
IMPORTANT: Consult a service repair manual for detailed instructions on how to remove and replace a fuel injector. - 2
Swap the fuel injector, with another. This other fuel injector has to come from a cylinder that you confirmed was not ‘dead’ in TEST 1.
- 3
Re-install the fuel injector rail as per instructions in a service repair manual.
- 4
Start the engine, after confirming you have no fuel leaks and that the fuel that spilled during the fuel injector swap has completely dried.
- 5
Perform the cylinder balance test per the instructions in TEST 1.
What you're looking for is to see if the misfire has now moved to the cylinder where you installed the fuel injector you suspect is bad.
Let's take a look at your test results:
CASE 1: The misfire moved to where the fuel injector was swapped. This test result tells you that the fuel injector is bad and needs to be replaced.
CASE 2: The misfire DID NOT move to where the fuel injector was swapped. If the misfire stayed put in the same cylinder (even after swapping the fuel injector), then you now know that the fuel injector is good.
Since the cylinder is still misfiring, you now need to check that the fuel injector is getting both power and its activation signal with a Noid light. The following tutorial will show you how to do a Noid light test:
- How To Do A Fuel Injector Noid Light Test (GM 3.8L) (although this tutorial is written with GM 3.8L equipped vehicles in mind, the info applies to your Honda Civic).
NOTE: If your Noid light test confirms that the fuel injector is getting both power and the activation signal, then the next steps are to make sure that neither spark nor compression are missing in that cylinder. The following tutorials will help you:
- How To Test Engine Compression (1995-2000 1.6L Honda Civic).
- How To Test Misfire Codes (1995-2000 1.6L Honda Civic).
- How To Test The Accord, Civic and Odyssey Distributor Type Ignition System (at easyautodiagnostics.com).
Fuel Injector Troubleshooting Guide
If you think you have a bad fuel injector but aren't quite sure where to start, in this section I'm gonna' offer you my fuel injector troubleshooting procedure. The following guide will help you get to the bottom of the problem, whether it's caused by a bad fuel injector or something else.
OK, the most important thing you need to do is identify the ‘dead’ cylinder. Because if you do have a bad fuel injector on your hands, your Honda Civic will have a misfiring cylinder.
These are the steps I take:
- Check for Misfire Codes.
- Unfortunately, the PCM usually doesn't set a specific bad fuel injector code, but when a fuel injector does go bad, you WILL see a Misfire Code.
- The idea here is to find the ‘dead’ cylinder. Now, if you have no misfire codes and yet the engine in your Honda Civic is misfiring, then you need to do a manual cylinder balance test.
- A cylinder balance test involves disconnecting one fuel injector at a time, while the engine is running, to see which one (when disconnected) has NO EFFECT on the engine's idle. The one, when unplugged, that doesn't cause the engine's idle to get worse is the one that belongs to the ‘dead’ cylinder.
- The next step is to check for spark.
- It's very important to eliminate the ignition system as the root cause of the misfire or ‘dead’ cylinder.
- What I'm looking for here is that spark is actually reaching the spark plug. This is accomplished using a dedicated spark tester on the spark plug wire.
- The following tutorial will guide you step-by-step thru' the whole procedure: How To Test The Accord, Civic and Odyssey Distributor Type Ignition System (at: easyautodiagnostics.com).
- Next, I remove the spark plugs and visually inspect them.
- What I'm checking for are for cracks and/or carbon tracks and/or oil filling up the spark plug well.
- Honda 1.5L and 1.6L engines have a bad habit of leaking engine oil onto the spark plugs and spark plug wire boot and this is a common cause of an engine miss (Misfire).
- If everything above checks out OK, I then do an engine compression.
- This is a fast and easy test but is so often overlooked.
- You can find this test here: How To Test Engine Compression (1995-2000 1.6L Honda Civic).
- Check fuel injector resistance.
- I also do a fuel injector Noid light test to make sure that the fuel injector (that belongs to the ‘dead’ cylinder) is getting power and the activation signal from the fuel injection computer.
- Since the fuel injectors are pretty easy to get to, I have also swapped them out to see if the misfire condition moves to the fuel injectors new location (as checked by the manual cylinder balance test).
The purpose of all of the my tests (above) are to eliminate the ignition system and engine mechanical condition first before attempting to blame or suspect a bad fuel injector.
And I can tell you that this diagnostic strategy has saved me from replacing some good fuel injectors and being able to nail down the ones that are bad.
More 1.6L Honda Civic Tutorials
You can a complete list of 1.6L Honda Civic diagnostic tutorial in this index:
Here's a small sample of the tutorials you'll find in the index:
- How To Test Engine Compression (1995-2000 1.6L Honda Civic).
- How To Test The Throttle Position Sensor (1995-2000 Honda 1.6L).
- How To Test For A Blown Head Gasket (1995-2000 1.6L Honda Civic).
- How To Troubleshoot A No Start (1995-2000 1.6L Honda Civic).
If you need and/or want to test the distributor ignition system to see if it's the source of the misfire condition (or misfire code: P0300, P0301, P0302, P03030, P0304), go here:
- How To Test The Accord, Civic and Odyssey Distributor Type Ignition System (at easyautodiagnostics.com).
If this info saved the day, buy me a beer!
