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Troubleshooting Ignition coils on 2002 Honda Civic

So my Honda Civic has been flashing my check engine light, which is telling my my cylinders are misfiring. I checked the ignition coils by removing them while the car was running and cylinder 2 and 3 I can remove and it doesnt change how the car runs. I put a new ignition coil In and that doesnt help so it isnt the ignition coils, Any Ideas on what it could be?

Fuel injectors?

But here’s a word of advice. Don’t unplug and plug things back in like ignition coils while the engine is running. Computers don’t like that.

Instead, swap components from one cylinder to another and then run the engine to see if the miss moves with the components.


Have you gotten the codes read. If your not in Ca, you can get it done at a parts store. Get it read and tell us the code.

Besides swapping coils and fuel injectors a compression test is in order.
Has the valve lash ever been checked?

My vote is with circuitsmith about the valve lash and a compression check.

IF an exhaust valve has tightened up then adjusting it to the proper spec can make the engine run well again.
However, how long it does run well can vary based upon how much damage the valve face and valve seat received because of the tight lash.

If it doesn’t matter whether cylinder’s 2 & 3 ignition coils are connected or not, the engine runs the same, well, 2 and 3 must not be doing anything. So there’s your problem. Usually the way a shop would go about this is to first determine the diagnostic codes, and if they also said 2 and 3 were misfiring, they’d switch the coils on 2 and 3 with 1 and 4 (if that’s possible to do), and see if the misfire moves to the other two cylinders or not. That way they can determine if 2 of the 4 coils are faulty. The same could be done for the fuel injectors, but usually those are hard to swap, so they’d test the compression before swapping fuel injectors. Best of luck.

Power to the coils should be checked also.

Every time I have checked my 1999 Honda Civic’s valve clearances ( whenever spark plug replacement is recommended), there have been several that were out of spec

One other time there was a CEL. One injector was not clicking like the others. I rapped it on its side with a screwdriver handle and it started working again. Added some Techron fuel system cleaner to the tank. All OK now at 169,000 miles.

The computer should be telling you precisely which cylinders you need to pay attention to here. Its either the coil or the plugs… When coils fail to function the computer knows about it pretty much always. Ive seen plugs fail and the computer was not flagging that cylinder as a misfire…so Im fairly certain the computer diagnostics are accomplished in differing manners between vehicles.

Shouldn’t be too difficult to suss out… Just go slow and use correct troubleshooting methods… Like @Tester mentioned…computers do not like things being unplugged “live”. You have 4 suspects…The coils, the Plugs, The Injectors and Cylinder compression. Start out with the easy and more common items first and then progress to more complex or expensive things afterward… I believe I listed them in ascending order of failure probability… If not Im close…