Failed Spark Plug is the title of my thread.

Just about the time I figured out that the Tundra computer didn't adjust to things like Pulstar's, like my Dakota did, and I got around to re-setting the computer, the plug failed and my mileage test ended.

I didn't notice much....until I traded back to the stock plugs and felt the dramatic difference in performance.
However, there was no MPG improvement and I attribute that to the computer monitering exhaust gas and thinking the better combustion meant a too-lean mixture and added fuel. Had the computer been re-set, I guess the result may have been different.

Bosch+4 plugs in the Dakota made no measurable difference in MPG
BUT
I never had to change them again, because with all those grounds they take forever to wear out.

Actually, I think that is what they base their claims of increased mileage on, the fact that if you're a dumbass and don't check your plugs for 100,000 miles, then theirs will be giving you better mileage than the ones that half eroded away 50,000 ago.

:D

Hrm. The Bosch+4 didn't exist (I don't think?) when I bought the +2's. Then again, I bought the +2's from Walmart :thumbdown:

With my car being so "old", would my car's ECU adapt to the plugs for an improvement in mileage? Right now I have a HAI setup, and have notice no mpg gain... just a hotter-running engine, but no ill-effects, so I haven't taken it off.

lol.

Well, I've also got a Tundra, an '05 4.7L. What plugs did you end up using...just OEM? (NGK/Denso)

I'm curious about the Halo's.....and also about doing that drilling and indexing mod...

Put the factory installed plugs back in.

Over the years, and in a number of vehicles, I've tried a number of type plugs. I used Splitfire plugs before I was told that they were invented by a marketing guy, then I looked at the mileage records I've always kept. DUH! Spent a lot of money for no measurable MPG.
I have not used the fancy-schmancy plugs with holes in them, surface-gap and such, mainly because I have Dr Jacobson's manual, and if he won't use them in racing engines, it seems to me they aren't worth the expense.

But, since I drive 150 to 300 miles a day, I am certainly open to anything that will give me better mileage. Gas savings will pay for a reasonable outlay.

Hey everyone.....just wanted to show you my little experiment. I just used an old Autolite spark plug as a test subject. I picked up 2 cobalt 1/16" drill bits at ACE the other day. 1 has a 118 degree point, and the other has a 135 degree point. I used the 135 on this and it didn't walk one bit.

I held the plug down using a quick grip clamp against my picnic table top, and I just used a cordless drill. Crude I know........but it worked out fairly decent. The bit drilled through it really easy. I didn't get it exactly centered, but it's not too far off.

Is this what the mod is like? I didn't cup out the center electrode...but would there be any gains if I didn't......and only drilled the hole?

I still have to debur it. I plan on doing this to my existing Iridium plugs in my Tundra.
https://img38.imagefra.me/img/img38/2...sm_c373e64.jpg

Well you do have about twice the amount of negative electrode edge for it to fire off now. I'd be worried about it burning through on the one side there, where there's not much meat left. Then it would probably come loose and drop the rest off in your motor... Jigging it up so you could drill dead center probably wouldn't be a whole lot of help, so you could use going down to a 3/64 or 1/32 bit or finding a plug with a wider electrode.

Just figured something, lots of folks test this with old plugs... the ones that have rounded off the nose and the negative... might actually help the spark to fire through the middle only vs doing it with new plugs.

Keep very accurate MPG records and report back.

One method I figured I'd try, since I don't have a drill press, is to take my dremel, and carve an indentation right where I want my drill bit to start. That way I don't have to guess while I'm holding the drill gun. The moment I begin turning the bit, it makes a little scar because of how hard the cobalt is.....so I need to get it right the first time.