spark plug intervals

[ugabulldog]

I searched but not much info,....what is everyone changing their plugs at 120k? I will be using OEM Densos. Thanks

[MasterTecInSTL]

I did mine at 105k but honestly they didn't really look bad and the car was running just fine.

I'd recommend the OEM Densos.. why get anything different? Especially when the difference in cost is marginal...

[MD1032]

OEM all the way. 120k is exactly right. Did mine at 107k. No real difference.

[Nusdogg]

I still need to do mines. I'm going with NGK though.

[SaGa]

Did mine at 103k and found out I was really overdue. My plugs were in terrible shape, probably having a lot to do with the vacuum leaks caused by the bad OEM intake manifold gasket that came on the early cars. I know that they say the plugs are meant to last for 120k, but that's only in certain conditions. Mine probably needed to be swapped several thousand miles sooner.

[T-Guy69]

I was thinking of NGK platinum’s in my XRS. I race my other car with NGK. Best plug I have found for my application.

Truthfully I am surprised the OEM plug is Densos. When I changed plugs in my 1987 GTS Corolla, they were NGK platinum’s

[hardtopte72]

Toyota owns Denso. Denso all makes the A/C system, injectors, coil packs, almost all the motors and switches, etc.

Toyota regularly uses both. Example almost all RWD Toyota V6 Trucks) have 3 sets of plugs from factory. 1 bank will have NGK and one bank Densos.

I have replaced several (maybe 30-40) sets of these Densos. Almost all of them had tons of life left at 120K miles. It doesn't hurt to replace them early or on schedule.

[MD1032]

When I replaced the Densos in my Toyota with NGK I can honestly say there was absolutely no visual difference between them....it was as if they came off the same manufacturing line.

[stir_fry_boy]

I put NGKs (yes, they were the correct NGK number) in my XRS instead of Densos. My car didn't like them much and started missing with CEL code P0401. I changed them again to Densos and the problem went away. For some reason my original plugs failed at 66 K in cylinder #1 only.

[MasterTecInSTL]

Originally Posted by stir_fry_boy

I put NGKs (yes, they were the correct NGK number) in my XRS instead of Densos. My car didn't like them much and started missing with CEL code P0401. I changed them again to Densos and the problem went away. For some reason my original plugs failed at 66 K in cylinder #1 only.

Seems strange that your #1 plug failed.. and then you replaced it and then got a P0401 (which is a #1 misfire code).

Makes me wonder if there is something else going on... possibly a failing coil or something.

If the P0401 comes back swap the #1 and #2 coils and clear the code. Then drive it until you get a code again. If it's still a P0401 then something else is going on. If it's a P0402 after swapping the coils then the coil at #2 is bad.

Then again it could just be coincidence. #1 plug failed and then the NGK plug you put in #1 just happened to be defective. I can almost guarantee this has nothing to do with the fact that you used NGK plugs though.

[dwiz3443]

When I first bought my 04 corolla it has 90K miles. It now has 137K should I change the plugs or let them run longer

[hardtopte72]

Originally Posted by dwiz3443

When I first bought my 04 corolla it has 90K miles. It now has 137K should I change the plugs or let them run longer

Would probably be a good idea to change them. Check out this link.

Read Me: Official 9th Gen Maintenance Thread. All you ever wanted to know!!

[MD1032]

Originally Posted by dwiz3443

When I first bought my 04 corolla it has 90K miles. It now has 137K should I change the plugs or let them run longer

Definitely. Here's a fun story. Pastor of my church has an '03 Camry, 150k miles on it. He tells me his car was having severe issues on a long road trip. Misfiring, running like garbage, like, fuel or ignition, something major. He had to stop at a friend's place overnight because it was so bad. They just changed the spark plugs and the problems were gone. He was planning on changing them when he got back and had assumed they would easily last another 30k past the maintenance interval of 120k in his manual since they were iridiums.

[stir_fry_boy]

Originally Posted by MasterTecInSTL

Seems strange that your #1 plug failed.. and then you replaced it and then got a P0401 (which is a #1 misfire code).

Makes me wonder if there is something else going on... possibly a failing coil or something.

If the P0401 comes back swap the #1 and #2 coils and clear the code. Then drive it until you get a code again. If it's still a P0401 then something else is going on. If it's a P0402 after swapping the coils then the coil at #2 is bad.

Then again it could just be coincidence. #1 plug failed and then the NGK plug you put in #1 just happened to be defective. I can almost guarantee this has nothing to do with the fact that you used NGK plugs though.

Yeah. I was thinking along the same lines as you. It was weird that as soon as I put Densos in it the problem went away except for slight hesitation especially upon hitting lift, but no CEL. So I ran good injector cleaner through it with 2 tanks of gas and it ran a lot better. Still no CEL. I then swapped #1 coil with #2 and still no CEL. Not sure exactly what it was but she sure runs good now. I always run Premium 91 octane too. That was 6,000 miles ago now.

The only thing I can think of is that the NGKs had an updated part number from what was on the market to my owners manual. One of the letters was off. The owners manual called for ones that were discontinued but replaced with new ones. No one could get the exact number it called for in the manual. I don't know if that was an issue or not.