When to replace spark plugs and with what?

"Wait until it misfires"


Later tonight found posting in "My Tacoma gets shitty gas mileage and it can't climb hills"

 

If I got 200K out of set plugs, I would be highly inclined to you the same make and model.

 

I assume you meant to say that^ ?

I would be highly inclined to stay as far away from that vehicle because the owner has neglected it.

 

NGK

Will others work, sure.
The NGK plug has THE best track record. I started using them almost 30 years ago. I've strayed a few times, sometimes seeking economy and sometimes seeking performance, but I always came back to NGK. There's not muck to a spark plug; a little ceramic, a little steel, maybe some type of plating? It's job is pretty simple. It ignites a compressed fuel/air mixture, even a cheap spark plug will do that. The difference really comes down to how long the electrode will survive before it is eroded to the point that it fails. For a relatively cheap, but critical part that I'd rather not have to deal with very often; I seek durability. There may be others that work as well but I know NGK's work!

 

That may be true but the NGK side was worn .004 more than the Denso's that I replaced them with from the dealership. Factory Denso's were gapped to .043 (still barely within factory spec) and the NGK were gapped to .047 after 30910 miles. That leads me to believe the factory Denso's are better plugs. When I went to the dealership the NGK weren't even an option as the factory plug replacements are Denso's.

Picture once again. You can "almost" see a difference between them. The "ground side electrode" on the Denso is thicker by far


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One thing that nobody has seemed to mention about keeping a set of plugs in for 200K miles is probability of them becoming seized into the heads. That is one risk I would not take. You can replace a set of plugs for the cost of a good lunch!

 

It was mentioned in another thread but yes, good point none-the-less!



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At what intervals should you change your underwear???

 

Same as spark plugs, when the gap becomes too great.

 

OK, I'll buy that. Denso appears to be a good plug. They also seem to have a slightly larger "hex" area for the socket to engage. I'll put Denso on my personal list of acceptable spark plugs. By the way, both of those look pretty good for 30K miles.

 

That is one thing that bugs me about the 100k interval for the Iridium plugs in the 2.7.

 

soo about 90-100k for the 2.7

 

Well, I looked at some plug manufacturers website and they were saying because of the zinc coating or something they put on their threads it acts as a permanent lube to prevent seizing to aluminum heads. Which was a problem long ago. Remember the days of helicoils and all that? And the days of carburetors fouling plugs? Plugs last a loooooonnng time in these modern engines.

IMO replacing plugs is money better spent elsewhere (six pairs of boxers, a good lunch ). As I said above, if I see a dip in MPG or I plug my OBDII in and it registers misfires, then I'll replace them. Or at 100k miles, that seems like a good point to do it whether or not there's any decrease in performance. I won't pull plugs just to inspect them, the OBDII can tell you all you need to know and it takes about 3 minutes.