I have a 2001 Civic LX, and I'm getting error codes P0300-P0304 (all cylinders are misfiring). The only symptoms as far as I can tell is that it is idling roughly and it sometimes doesn't start as easily as it used to. Spark plugs are new. There isn't oil on them. Someone suggested changing the wires. I know I have coils, unlike the older Civics, but is it possible the wires connected to the coils need to be changed, either the ones circled in red or the ones circled in blue (see picture)?

Any help is appreciated. Thanks.

 

Those wires are low voltage and don't degrade like the high voltage wires which were used on distributor systems do. They should last the life of the car.

Idling rough you should check the valve adjustment first.

 

Ok, thanks. I'll look into checking the valve clearance. After a quick google search for checking valve clearance, and of the causes for problems with this, it seems that carbon buildup would be the most likely culprit in my case (source). One guy suggested seafoaming my car, which I may do. If carbon buildup is part of the problem, maybe this will be part of the solution, as my car has 220,000 mi. on it.

 

It probably one of the coil, one bad coil can give you multiple misfire code. Try flip flop the coil and see.

 

How will that help me learn anything, since all four cylinders are misfiring?

 

btw, my last post was a sincere question, not me being an jerk (though I certainly am prone to being a jerk at times).

 

What Droopy was saying is that the cylinder numbers reported by the ECU codes aren't always accurate.

You can see if the problem is confined to one cylinder by disconnecting the fuel injectors one at a time with the engine idling. Disconnecting a good cylinder will make it idle worse. Disconnecting a bad cylinder won't have much effect.

If it is one cylinder only, then swap the coils between that one and one of the good ones and test if the problem followed the coil.

But first, take the valve cover off and do the valve adjustment. This is a periodic maintenance procedure that must be done in any case since unlike most other cars, the D series engines do NOT have valve lifters which automatically compensate for wear.

 

Ok, thanks mk. After your clarification, it makes more sense. I'll have to figure out where all of this stuff (fuel injectors, valve cover) is before I can do anything though. Can you describe to me (or show me) where the valve cover is?

 

Really if you're not familar with basic parts such as those, you should find someone who is more experienced with cars to help and teach you in person.

Or watch a bunch of youtube videos such as this one. His car is a 2000 model, which is slightly different, but the concept is the same. There should be videos specific to the 2001-2005 type of engine as well.

 

Many thanks. I appreciate it.