In recent weeks I've noticed that after highway driving, my 1993 civic would idle roughly, almost to the point of stalling. I drove 8 hours to my mother's house for the holidays and now it is idling and running terribly. I checked the plugs and found that they were bady fouled. I changed them immediately but there was little, if any, effect. I then changed the wires but again, no effect. I'm thinking it's possibly the coil or the fuel injectors but I don't know if it could be something else as well. I have a 1993 Honda Civic EX w/1.5L D15B7 SOHC 16-valve engine. Yes it really is an EX with the 1.5L because that's what they have in Canada. The check engine light does not come on as a result of this problem so I'm assuming it's not the O2 sensor. Any advice would be greatly appreciated! :D

Replacing the Ignition Control Module (ICM) and coil should solve the problem:

https://www.askmehelpdesk.com/cars-trucks/faq-how-troubleshoot-repair-maintain-hondas-selected-other-vehicles-46563-4.html#post265896

Replacing the Ignition Control Module (ICM) and coil should solve the problem:

https://www.askmehelpdesk.com/cars-trucks/faq-how-troubleshoot-repair-maintain-hondas-selected-other-vehicles-46563-4.html#post265896

Well I've managed to determine that it's cylinder #2 (second from left) that isn't firing. I've changed the spark plug (for the second time) and even tried changing wires. It still refuses to fire and I don't know why. That eliminates both the coil and the ICM. The plug I removed smelled of gasoline so my injector is working and I got shocked by the wire so I know the wire is defective. There is a good amount of compression in the cylinder and even though I tried wires that worked on cylinders 1 and 3, it still won't fire. This is quite a mystery and it's driving me nuts... lol

I don't agree with your diagnosis.

That may be but if it was the coil or ICM, wouldn't it affect all cylinders equally? When I disconnect cylinder 1, it acts like it's about to stall, same with cylinders 3 and 4. When I disconnect cylinder #2, it has no effect which tells me that it's not using that cylinder to begin with.

Not necessarily. The microchip inside the ICM may be in the process of totally failing. At this time, it will not "fire" cylinder #2 when directed by the ECM--soon it may not fire at all. I would be surprised if replacing the ICM didn't solve the problem. They are problematic components, along with coils, that really should be replaced every 120,000 miles or 10 years, whichever comes first. Heat and electron migration eventually destroys these components, especially ICMs.

Disconnecting the spark plug wires, while the engine is running, over-stresses the coil and can ruin them very fast.

The only other possibility is that the internal sensors (CKP, TDC, and/or CYL) are bad. Since they are not serviceable, the solution is to replace the distributor housing (genuine Honda only) and then install the new aftermarket ICM and coil. Always begin by replacing the ICM and coil first.

I do have to agree with you however that this doesn't explain it recent behaviour unless it was the increased heat causing too much resistance in the wires. I had to go back because the wireset I bought was defective (game me a couple of good jolts). I've yet to put the new set on because I'm sure there's more to it than just that.

Well I'm going to follow your advice because you obviously seem to know your stuff. I'm having the ICM tested and I'll see what's what. Strange thing is, the wire is sending current (that's how I'm getting the jolts), it's just not seeming to send a spark into the cylinder.

Bench testing these components is virtually worthlesss. If they test bad, they are bad. If they test OK, they may or may not be good. The same thing goes for coils.

Well I found out the problem. Burnt exhaust valve, can't get sufficient compression. Getting a new engine tomorrow for $750 installed. :D

That will do it. With your new engine, only use full-synthetic 5W-30 engine oil. Change oil and filter every 6,000 miles or 6 months, whichever comes first. If you do this, your engine should last 250,000+ miles.