92 Civic VX Spark Plug Fouling?

[cmlamb2vx]

I've attached two photos of my spark plugs. They are placed in the order of engine placement, right to left, timing belt cover is right and left is battery side. Is this an example of carbon fouling? What would cause only two to do this? Civic doesn't smoke. This plug condition has occurred within about 1K miles or so. No engine codes but my FE seems to be lacking. Any thoughts on the problem or where I go from here to diagnose?

[jadziasman]

From what I just read about spark plug appearance, it is likely that you have either a cracked distributor cap or faulty plug wires for cylinders 2 & 3.

[101mpg]

I agree - check your cap & rotor first, plug wires (dielectric grease on the connections can help - VERY cheap fix sometimes) next.

How many miles on the vehicle?

Oxygen sensor can be fouled as well. Could be a faulty plug or two also.

CHEAP fix is swap out the plugs first - if it continues to repeat, then you know t's not the plugs.

Make sure all your connections are tight - most people ignore dielectric grease on the plug/wire/cap connection.

If you open up the cap and see fouling inside - sometimes just scraping the contacts (and edge of rotor) will help, although I would replace the cap & rotor if you see fouling of either. Always replace cap & rotor together.

Could be a faulty coil as well. I've seen this problem before, in fact had to walk a couple miles home with my gf at the time nine years ago on my birthday due to her CRX having a coil go bad at about 70K miles. It was sluggish prior to meltdown, and the plugs had to be replaced. Coil can be checked with a multimeter, if you don't know how, most auto parts stores know how to check this, and they should have instructions on how to do it properly at their store.

Check these items and get back to us with the results. 95% chance one of these items is bad.

Wouldn't hurt to put some fuel additive in with new plugs and help clean the oxygen sensor either.

[cmlamb2vx]

OK...appreciate the quick replies. Just turned over 175K today. Was going to replace the plugs and wires as I have been reading some on the site about the importance of the having the correct plug type and good wires. I'm sure that the last set of wires I put on about 10 years ago were most likely cheapies. Will go with some genuine Honda wires this time. I've recently replaced the distributor (entire set) due to the bearing going out and had the timing belt, water pump, accessory belts replaced, too, all by a certified Honda tech. Will work on your suggestions and keep you posted. Thanks.

[101mpg]

I wouldn't get Honda wires - get some better aftermarket wires (that could be its own flamewar) for the same price or cheaper, DEFINITELY see how long it's been on that oxygen sensor.

I opt for other plugs besides NGK standards, (Bosch +4 are my favorite), I would at least get a U/V groove type plug (splitfire, your other favorite, etc.) rather than the NGK. If you do use that sort of plug, dial them in (shims) for best FE.

[cmlamb2vx]

I thought this was interesting. I measured the resistance of my spark plugs with my trusty DVM and the ones that looked normal were around 3560 ohm while the fouled looking plugs were both at 3960 ohms (not sure of the units). What do you suppose this means? I would think that they should all read fairly close like the two normal looking ones. I'll be sure to check all four replacements that I pick up.

I also took a look at my plug wires. For reference they were Bosch Ultra-Premium 7mm Opti-Layer Mag Core wires. Check the resistance in the wire for the fouled looking plug read 1250 ohms and for the wire in the normal looking plug read 1376 ohms. Does this mean they're still ok?

[101mpg]

Are the wires the same length? The longer the wire the more the resistance. People don't take this into account. (I don't know the exact #s - been a while since I fiddled with plug wires, now you're making me start a new project.)

Go to the auto parts store and tell them exactly what you're doing. They should let you measure the resistance in one (or ideally more) set(s) of wires. Get what you think.

It's good to see you're being so thorough. I would not like to have higher resistance in my plugs but I would again check vs. baseline (other new plugs, as many as they will let you test). 400 ohms seems fairly high to me for variance on the plugs.

Whatever you do - USE DIELECTRIC GREASE on both ends of the wires. (Lots of emphasis added here.) That will help regardless.

I don't know if you have tried cleaning the fouled plugs - I would clean them well, then check the resistance again. If it goes down, the extra resistance was due to the plugs being fouled.

Make sure to check the coil too. IIRC there are a couple of tests that need to be done to it.

Remember on the plug wires - check all of them vs. your baseline. Usually on a 4 cyl there are 5 wires - one from the coil, four for the cylinders and they are all of differing lengths. Unfortunately no one has ever come out with a distributor that has all wires exactly the same length. The only improvement over this setup is the one coil per plug computer controlled method, which leaves little for us to tinker with.

[cmlamb2vx]

You're right on about the lengths of the wires. The slightly longer (no. 1 plug) had the slightly higher resistance compared to the slightly shorter no. 2 plug wire. I have cleaned the plugs several times before and they end up looking the same. Used dielectric grease last time I did this (1st time I used it), but will make it a routine from now on. Appreciate the help and will continue to post updates.

[101mpg]

Sounds like plug wires may be okay then - but I would check them against baseline new wires. Any parts shop worth its salt will let you check new wires like that, as they would like your business. If the wires are okay you shouldn't have to replace them, as they can be pricey, especially for good wires.

[cmlamb2vx]

Well, got some new plugs. Checked the resistance and I couldn't measure any (open circuit). I also checked when I put those old ones in and it was back in '01 and they have about 58k miles on them. I think there were just shot. We'll see how the new ones do. I also put in some new wires. Will start checking components next. I did check my o2 sensor. The voltage at operating temp was ranging between 2.3 and 3.0 volts which seemed kind of high. I need to check it when cold and see how it looks as it warms up. One thing I have found is that there is supposed to be engine voltage on the heated wire for it and it was only giving me 6.6 volts. Need to check my ECM and my main relay circuit according to Chiltons.