Hi there. I have a 92 Civic DX, and had it fail a smog check in CA because readings showed it was running fuel rich. With the help of my cousin who's a mechanic, I checked the cylinders to see if they were fully firing, and it turns out the #3 (facing front of the hood) cylinder wasn't fully firing. It's been 2 years since I replaced the spark plugs, etc., so I replaced the plugs (just the #3 plug initially, for testing), wires, cap, and rotor, and while the engine sounds like it's running smoother, I still get an occasional misfire on the #3. I believe it's still firing though, as when I pull out the wire for the cylinder, the engine runs slightly more rough than before. Any thoughts? Thanks!

Jon

 

How do you know that you still have a misfire in cyl 3? Have you tried to pass emissions since replacing the plugs, wires, cap, and rotor?

 

Sorry for the latent response. I've yet to take it in but will be doing so tomorrow. I still strongly suspect some sort of a misfire, since whenever I pull the wire to the spark plug from the 3rd cylinder, the engine runs slightly more roughly, but not much compared to doing the same for the other cylinders which almost kills the engine. If the 3rd cylinder is not causing much of a difference with the wire in, already, wouldn't that mean there's some sort of misfire, or something's blocking the fuel?

 

The cylinder closest to the distributor is #4. The one at the other end is #1. You should swap the fuel injectors around and also run a compression test.

 

My mistake, I'm thinking #2 then.

Would you know if somebody's posted how to switch out the injectors?

 

Also, not sure if this counts, but when I switched out the spark plugs, the #2 plug didn't seem to look that different from the others--basically just had a hard, white covering (carbon?), for all of them. Hadn't replaced it in 2 years, so maybe that makes sense. If the injector was leaking and/or running rich, wouldn't it be more black? Just a random thought. I still should try the pressure test and injector swap.

 

Well, switched fuel injectors, didn't do anything. I'm guessing now it has to be something funky in cylinder #2. Could get a compression test--but what does that have to do with the engine running too rich? In any case, I've yet to take it in for a retest, but will do so tomorrow, see what happens.

 

If a cylinder misfires, unburned gas will go into the exhaust stream, which is similar to what happens when running rich.

 

So what I'm wondering now is what would cause the misfire, if nothing's wrong with the injectors and plugs/wires have been replaced?