Hi, I'm really glad to have found this forum as I really could use some help:

We have a 1994 Honda Civic hatchback, four cylinder, standard transmission. We have trouble with something that persists only with the spark plug that's second from the left. A couple of years ago, we were told the engine was running on three cylinders after getting an oil change. We were surprised to hear this, as the car seemed to run fine, start well and had no backfiring nor anything else unusual. We got home and saw that the spark plug well (second from the left only) had oil in it and the spark plug was coated with oil. We suspected that the person who did the oil change was responsible, long story, but that does seem to be true. The well was cleaned out and the spark plug was replaced. The car seemed fine, but after our oil change the next year, we were told again about the three cylinders. We checked again, but this time there was no oil nor anything wet, but the spark plug was coated with a dark brown/brown colour. We changed the spark plug, but the issue persisted with that spark plug. We recently changed the spark plug wires and it didn't help. The air filter is fine and the distributor cap contacts are clean.

We don't drive very much and generally for short trips, which possibly is a contributing factor. We're just trying to figure out what this could be as it's only happening to that one spark plug. Any help would be appreciated.

 

Welcome in,i think you solved your own problem,the fact that you dont drive this vehicle enough is the problem i believe. The plug is fouling because self cleaning plugs need heat to burn off residue ,try taking it out and driving at least 20 minutes at a set speed to heat up the plug,if this doen't help try using a hotter plug the parts house can reccomend one for you. Good luck

 

Thanks for your reply @bucwheat . It makes sense to you that the fouling could be because we don't drive enough even though it's only on one spark plug? I'm glad to hear that if so. Hubby will have the chance to drive the car faster for at least 20 minutes tomorrow, so hopefully that will help. By a "hotter plug," you mean one that gets hotter more easily so it burns off residue at a lower temperature?

 

If the car was not being driven enough then it would foul all the spark plugs.
What it might be ... a busted head gasket, worn piston ring, valve not seated properly, crack engine block
There really is many things that could cause this.
The job now is to determine which one it could be.
Test.

Do a power balance test
Remove the spark plug wire or boot to see if the engine revs differently
Will tell you if it is that cylinder with the issue
If it is that cylinder then do compression test and/or leak down test.
That will tell you the condition of the cylinder ... valve, rings, gasket will be suspect
Of course there are other possible tests.
But, I think you get the point

Good luck

 

Thanks for that suggestion. I suppose since that one spark plug is the only darkened one, it stands to reason that when we do this test it should sound the same if (in fact) we're running on three cylinders. But it's definitely worth trying. Maybe we're not running on three cylinders, who knows?

 

Yes, if you see no difference then cylinder is suspect.
If there is a drop in engine then cylinder is contributing power
Verify if there is a big issue or small issue.