4stringking

Hello all,

I have a 98 Civic DX 5-spd sedan. Last week, my wife noticed the idle was rough. This lasted for a couple days before the CEL came on. Once, she started it, and the CEL came on and began flashing, while the car ran rough at all rpm's. I was out of town and was unable to check it until the following day.

The codes thrown were all misfire related (0300, 0301, etc). I decided to start with the spark plugs. It looked like they needed to be changed anyway. I also pulled the fuel injectors and rail off, cleaned them thoroughly, and checked to see if they were all clicking with the engine running. None of this worked, so I went on to the distributor cap and rotor. It seemed like this marginally helped, but all cylinders continued to randomly misfire.

I was able to drive it across town to another location. En route, I filled up the tank and added an octane booster to see if that changed anything. I pulled the valve cover off, changed the gasket (needed to be done anyway) and took a look at the timing belt (everything looks in good shape and in time). The color of the oil looked normal, and all my fluid levels are normal. No color to the exhaust, and by all accounts everything looked fine. I decided to put some di-electric grease on all of the electrical connections from the distributor to the spark plugs, just to see if there were any issues with bad connections or something.

Lo and behold, the car fired up normally, without sputtering or misfiring. No CEL, no nothing. Took it out on the highway and got it up to 70 without a problem. Ran great for the rest of the night, so I took it home and it sat for a day.

After a day of nothing, I tried to start it up, and it took about 4 seconds of cranking the engine for it to start. Immediately, the CEL came on, flashing, and the car is misfiring as badly as before. I can smell the unburnt fuel fairly strongly, especially at idle. This makes me think that fuel pressure or injection isn't the issue. I still haven't changed the plug wires, since they are in great condition and I didn't notice any excessive corrosion on the contacts. No codes are being thrown as far as any bad sensors, only misfire related ones. I'm just trying to figure out if this is electrical or air intake related. Does anyone have any ideas for continued troubleshooting? I'm also working with a limited budget, so I'm trying to take care of the inexpensive things before dropping serious cash.

Thanks!

dascivic96

my car was doing something similar, really slight misfire from time to time at idle, and seemed like alot more hesitation when accelerating, i swapped out my plugs and fuel filter and it stopped. you might wanna try swapping the filter out, easy and cheap and good to replace anyway if you havent in a while. just a thought!

hope you can figure it out, good luck!

Former User

There's diagram in the FAQs sticky for testing the coil.

AutoZone will test the ICM for you.