Any reason to change spark plugs if engine doing fine?

[paulri]

The manuals for both of my cars say to change the plugs at 30K. I might have had them changed the Civic with a tune up at 150K, but they would not have been changed after that point. I bought the car at 80K, don't know if they were changed before then, the previous owner had no maintenance records to show me. As far as the Sienna goes, it had a tune up at 103K, but they have not been done after that point.

My gas mileage is at or above adjusted EPA for these two vehicles. If I don't notice any misfiring or sluggish response, is there any reason for me to change them before my mechanic says they absolutely need to be done?

Is there anything else that might go wrong with the engine, if I don't change the plugs more often?

 

[JeffKeryk]

Probably depends on what's in there now. The exotic metals last longer; in some cases 100K miles. I would pull 1 and take a look. Heck, I would pull 'em all and take a look, but that's just me.

 

[Silk]

It's called preventative maintenance, the other method is called fix it when it breaks.

 

[spasm3]

I always change non precious metal plugs at 30k especially on a waste spark system.
Platinum around 50-60k or per the owners manual.
Put iridum im my truck for the first time, i'd go 75k-100k or so on those ( if i have it that long).

I look at it this way. If you push the limit on the plugs and get into a misfire situation ( especially if you are not near home) you may kill the catalytic convertors.

Thats why i change plugs a tad early and i also change upstream 02 sensors around the 75k mark.

 

[The_Jeff]

If your spark gap is too wide it stresses your coil(s) which is/are much more expensive than plugs.

And your plugs can seize in the head or come out rough if too much time passes. Especially some Ford V8s.

 

[spasm3]

Originally Posted by eljefino
If your spark gap is too wide it stresses your coil(s) which is/are much more expensive than plugs.

And your plugs can seize in the head or come out rough if too much time passes. Especially some Ford V8s.


+1

I did not mention it, but i always undergap my plugs by .005. I have never replaced a coil, even on a saturn!

 

[2strokeNorthstar]

Personal opinion or how long can you wait before thinking about it is more work than just doing it. I changed OE plugs at 150k in my Cadillac Northstar. Shocked when it did nothing. No MPG increase or idle change etc. Newer cars I usually change at 100k for piece of mind.

 

[paulri]

"Coils" as in ignition coils?

I just had to change that in my Sienna.

Originally Posted by eljefino
If your spark gap is too wide it stresses your coil(s) which is/are much more expensive than plugs.

And your plugs can seize in the head or come out rough if too much time passes. Especially some Ford V8s.

 

[Jim K]

Originally Posted by eljefino
If your spark gap is too wide it stresses your coil(s) which is/are much more expensive than plugs.

And your plugs can seize in the head or come out rough if too much time passes. Especially some Ford V8s.

This is the right answer.

 

[2strokeNorthstar]

Ford's have their own special problems. Not exactly time related. More underlying design issues.

 

[redhat]

I changed the plugs in my Accord at 50k. Pulled out OE Denso Iridiums. Plugs looked great. I put NGK Iridiums in their place. At 100k, I took the NGKs out and put those same Denso plugs back in.

I was more concerned about a potential plug getting stuck in the aluminum head.

No issues here, will prob put the NGK back in at 150k (oh wait here we are...)

 

[atikovi]

111,000 miles on these I just pulled from a Chevy Spark. Some deposits and increased gap but ran just fine.

 

[bdcardinal]

I do mine probably too soon, but they area cheap and it is easy to do. Plus it alerted me to a leaking spark plug tube seal which I was able to take care of.

 

[Snagglefoot]

Originally Posted by paulri
The manuals for both of my cars say to change the plugs at 30K. I might have had them changed the Civic with a tune up at 150K, but they would not have been changed after that point. I bought the car at 80K, don't know if they were changed before then, the previous owner had no maintenance records to show me. As far as the Sienna goes, it had a tune up at 103K, but they have not been done after that point.

My gas mileage is at or above adjusted EPA for these two vehicles. If I don't notice any misfiring or sluggish response, is there any reason for me to change them before my mechanic says they absolutely need to be done?

Is there anything else that might go wrong with the engine, if I don't change the plugs more often?


You should be able to find the equivalent Iridium sparkplug for these. For the Honda NGK 2477. For the Toyota Sienna NGK 3764. A lot has changed in the last 13 years for the Toyota and 21 years since they built your Honda. Once you have Iridium, they should be good for 100,000 miles. Get them changed and don't worry about them for years.

 

[joekingcorvette]

I have almost 79,000 miles on my Civic. I think I might change them today.

 

[69GTX]

My last car was a 2002 Lincoln 4.6L DOHC with 82K miles. I didn't change the plugs when I owned it because it ran perfect....and the plugs were designed for 100K+ miles. When I asked other owners about many said they didn't touch them until 120-135K miles. And there are downsides to changing the plugs early.....like they are a huge pita to get out, especially the rear bank along the firewall.

 

[HangFire]

A philosophical issue, I guess.

The point of maintenance is to PREVENT degraded conditions. That means replacing wear items near their end of life, not past their end of life.

Not everyone tracks mileage at every fill-up, and would notice a slight falloff in fuel economy, as the plugs slowly go. With modern spark systems there might not be much falloff, but at eljefino points out, that comes at the price of stressing (and possibly ruining) your coil packs.

And as bdcardinal points out, routine maintenance gives you a chance to catch other conditions early.

I've run plugs a little past their intended life, or replaced them a little early, as is convenient for me. However I never considered just running them until something went wrong.

 

[cheech279]

Most brands of iridium spark plugs have a recommended change interval of about 100K miles. I recently changed from NGK Iridiums to Denso Iridiums in my Ridgeline at 12 years and 87,000 miles. The old plugs looked surprisingly good.

 

[paulri]

Noted. Both plugs found at Autozone site. Thanks.

Originally Posted by Snagglefoot
Originally Posted by paulri
The manuals for both of my cars say to change the plugs at 30K. I might have had them changed the Civic with a tune up at 150K, but they would not have been changed after that point. I bought the car at 80K, don't know if they were changed before then, the previous owner had no maintenance records to show me. As far as the Sienna goes, it had a tune up at 103K, but they have not been done after that point.

My gas mileage is at or above adjusted EPA for these two vehicles. If I don't notice any misfiring or sluggish response, is there any reason for me to change them before my mechanic says they absolutely need to be done?

Is there anything else that might go wrong with the engine, if I don't change the plugs more often?


You should be able to find the equivalent Iridium sparkplug for these. For the Honda NGK 2477. For the Toyota Sienna NGK 3764. A lot has changed in the last 13 years for the Toyota and 21 years since they built your Honda. Once you have Iridium, they should be good for 100,000 miles. Get them changed and don't worry about them for years.

 

[paulri]

Folks, thanks a lot for helping me out with the info given above. Because a lot of times, people only read the OP and then reply, I have a few more questions that I decided to put in a new thread. You can find it here: https://www.bobistheoilguy.com/foru...8/three-spark-plug-questions#Post4965978

Feel free to pitch in with answers if you want to.