I have an old 1994 EX without much mileage in recent years. The Honda maintenance schedule says to replace spark plugs every 24k miles or 2 years, whatever comes first. I'm curious if the experts on this site stick to that rule or if you go more by mileage than time in the case of a sparsely driven car. I ask because the spark plugs on this car were last replaced in 2005, however, I've only put 13k miles on the car since then. (There are 167k total miles.) Also, I've read in a few places that new plugs are advertised to last much more than 24k miles or 2 years, so perhaps it is not unexpected that I have plugs from 2005?

In terms of performance, I have no starting or stalling issues, and my CEL is not on. My mpg are ~24 normally and almost 30 on a recent long trip. I haven't seen any mpg dip since I started keeping track. The car passed a CA smog check in September. The numbers came in a bit lean and imperfect, but another mechanic suggested they could have been the result of a lazy test. In general, the car runs fine but maybe vibrates more than other cars, especially at idle. But, I'm told that can also be due to worn motor mounts.

I suppose I don't have much to lose by having the mechanic check the plugs, etc., except the cost of an hour of labor, and I have to take the car in for an oil change soon in any case. But, I hope I can hear the opinions of some disinterested experts with a lot more experience in these matters. Thanks!

 

Here's one way of thinking about the sparkplug schedule...
Cars that hit the time limit before they hit the mile limit, are usually driven on short trips. Short trips are harder on spark plugs, there's more engine-starting for every 1000 miles. Long highway trips sorta allow the plugs to stay cleaner & last longer.

So if you drive the car LONG trips, then park it for awhile, you can probably get away with the spark plugs.

But if you actually drive the car short trips, get some plugs. They're pretty easy to change yourself, and I think the stock plugs for a 94 aren't horrible expensive either.

 

Thanks. I drove the car across the country and went on a long trip once or twice. But, definitely more than half of my 13k miles since 2005 come from trips 10 miles or less one way.

I don't have enough tools and time to learn how to change spark plugs right now, but I'll have a mechanic change them out (unless I hear a vastly different opinion here). Thanks for your input.

 

It's one of the easier jobs on a car.

You can probably go somewhere like an AutoZone-type store when they're not busy; they migh show you how when you buy the plugs and the wrench. Don't actually do it in the parking lot unless you want to wait for the engine to cool off.

 

OK, I'll look at the service manual I found online to see if I can do it. But, when you change spark plugs aren't you also supposed to check other things like wires, caps and the fuel filter? How hard is it to tell if those other components need replacement, and are those components more expensive or difficult to work with? Thanks.

 

Changing out the plugs, wire, cap/rotor are simple. To pull the plugs all you need is a T-handle plug wrench. There is a rubber grommet inside that holds the plug, loosen the plug (lefty loosey/righty tighty). Once the plug is out, place the new plug in the socket/grommet and install.

When you change the cap/distributor/wires:

On mine (2000 EX4) there are three screw's/bolts. Either use a screw driver or a socket (I believe it's a 7mm) Once the cap is off, install each new wire from the old cap into the new cap and follow each wire to the plug. Now all of the wires are installed on the plugs and wires on the cap are in the correct orientation.

The next thing to do is remove the rotor. There is a screw, remove it, pull off the rotor and install the new one. Now install the cap with the three new screws and you are done.

The last time I replaced the plugs was 50K miles ago. I used the Bosch +4's. I've heard that you should only install Denso Iridium plugs and that Bosch plugs ruin your ignition. I personally haven't had any problems, but I'm considering using the Bosch Iridium the next time I change them.

 

Great. Thanks for the instructions.

50K is double the spec in my 94EX manual! Is the spec higher for spark plugs now, or is the manual just overly cautious? How long has it taken you to put on 50K miles?

 

At some point Honda started calling for platinum plugs that cost 3x as much but last 2x or 3x longer. I had a 2003 Accord that called for plugs every 105k miles. Different years have different stuff.

Make sure you remember (draw a picture?) which wire goes to which plug, and which post on the distributor. If you get em scrambled the engine won't start.

Honda factory plug wires are pretty good, they seem to last forever. You can check the plug wires like this...
- Cold engine & complete darkness, like 4am or something like that.
- Open the hood & turn off all the lights.
- Start the engine & look under the hood for arcing - dull blue glow around the wires.
- Anyplace that's arcing or glowing - that means the insulation is deteriorated & you need a new wire or cap or whatever.

 

You're describing a car that's not broken, so why fix it? 13K miles on plugs is fine

Put the "hire the job done" money in a cookie jar for when the car has an issue. $.02

 

Like, Jim said they are scheduled to be changed every 105K miles. I've always changed them around 50K. Also, be sure when you remove the cap to put the new cap at the same orientation as the one that was removed and remove the wire/s 1 by 1. The firing order is 1, 3, 4, 2. If you look at the cap and the #1 plug, and follow to the next wire on the cap, (going clockwise) it should be #3, #4, #2. The wire's are also different links, #1, (closest to the belts/longest) #4 (closest to the distributor/shortest).

With 16K on the clock, like Uhoh said, you truly don't need to do anything at this point. I just changed out my cap/rotor at 152K and it still was fine. I changed the wires at 100K with Bosch Premium wire.

You can keep this information for future use.

Good luck!