mkgarrison5

hey guys i am new on the site and just wanted to say that this board is great! tons of info. now to my question

i too am on the market for some new plugs for the 2002 taco 4x4 3.4ltre. the factory calls for the regular denso plug and i am curious about this iridium plug.. does anyone have any complaints on the iridium and would it be worth my while and $ to change from regular to iridium?? i drive tons of miles a year. my taco has 79k miles and i bought it with 52k miles and that was less than a year ago. tons of highway miles!! so i have 20k sometihng miles in less than a year..

MTL_4runner

I would just go with the stock plugs unless you're going to move towards a supercharger. I change mine about every 50-60k miles to make sure they are always in good condition and I get the best gas mileage possible. You shouldn't see any issues running either plug type.

Speedy

I've got NGK Iridiums in my 2002 4Runner 4x4 SR5 with no issues. Run 87. No pinging and I've tried to make it ping and can't.

Speedy

I ran the stock plugs to 60K in my 2002 4Runner 3.4. I shopped around and found that O'Reileys has the NGK Iridiums for $6 a plug. A VERY good deal. The same plug was $13 at Advance Auto and Autozone.

I will say my truck runs much better, but can't say if that's just because the plugs are new, or because they're iridium.

Sdkfz251/7

I put some Bosch Platinums +4 in my Taco 2 months ago and I am replacing them tomorrow with NGK's. Lots of pinging. My 3.4 runs like crap. Gas mileage seems worse. Stick with OEM.

Ryan

Siciliano

Thanks MTL!!!-

I spent the day taking out, cleaning and re-gapping the plugs, inspecting the coils, and wires a re-installing it all only to have the same problem. I went ahead and ordered 3 new ingnition coils. I will in fact take MTL's advise, and get the factory spark plugs. At the dealer only (?) or at my local advance or napa auto? To tell you all the truth, I bought this truck in 98, put 100,000 miles on it and have only had to change a starter,( wires and plugs too), and an OXY sesor. I have changed the oil every 2000 miles with regular oil until I put synth in and change that every 4000. So it' about due for some of the original components to go. I have gotten away with murder I think. Thats why I just went ahead an ordered the coils. That will surely eliminate that as a question. Other than that the truck is in beautiful condition. I will post a picture when I learn how to.
I really am greatful for all of your ( all of you!) knowledge and willingness to teach an old dog new tricks. Ciao!

Speedy

You can get the stock plugs at Advance Auto, Autozone, O'Reiley's, etc.

I would have just checked the coils with a DMM. That tells you if they're good or not. If you don't know how the dealer should do it for free. Takes 5 minutes.

MTL_4runner

Chances are most (if not all) of your coils are probably still good. The way to test is to put in new plugs (so that isn't an issue), then swap the coil positions (ie take the one from #2 and swap it with the #4 or #6 position and then see if that makes the misfire move too....if it does, then you have a bad coil). You can also check the coil's resistance, but that isn't always definitive either. These trucks are very well built so even though you might feel like high mileage warrants new parts, that isn't always the case. If you're dying to spend money on new parts, I'd suggest getting a new front O2 sensor (leave the rear one until it throws a code).

mkgarrison5

quick question-- how tight do you guys tighten your spark plug? i just tighten mine to a decent snug. is there a better way by chance or should i say more technical way? lol

Phat Ham

On engines with a lot of miles you can get carbon or sludge buildup inside the combustion chamber. This effectively increases the compression ratio, which can cause knocking.

Phat Ham

use a torque wrench

mkgarrison5

what do i torque them to? whats wrong with just a good "hand" tightening??

Phat Ham

Don't know what the torque spec is off the top of my head. I think it's 18 ft-lbs, but don't quote me on that. The problem with tightening by hand is it's really easy to over torque them, and with the soft aluminum head you can strip the threads.

gpcollen1

Nothing wrong with 'hand tightening' if you have a good idea as to the torque and experience. Without that, you are really just guessing.

Speedy

I couldn't find the torque specs and don't have a repair manual. Spark plugs have a collar on them that crushes as it's tightened. When installing them you'll feel it crush if you just take it slow. Once it's crushed turn about another 1/4 turn and you're done. If you find the torque specs, obviously use them.

MTL_4runner

I don't think I have ever torqued a spark plug with a torque wrench and as an ex-mechanic I've changed alot of them. I use the number of fingers on the ratchet to limit the power/torque I can apply. For spark plugs I tighten them as much as I can with 2 fingers on a standard 3/8" ratchet. You'll feel the washer on the plugs crush down and you shouldn't be going any beyond 1/4 turn after you feel the washer stop compressing.

surf4runner

i have found that the +4 offer no performance improvements over the +2 in any FI engine. more of a marketing gimmick, the coil voltage does not increase so why would the spark.

one of these days ill switch back to the NGK i have

mkgarrison5

so what is the verdict here?

go with factory denso or ngk

or

go with denso, ngk iridiums?? with iridiums i have noticed from what i have read and heard that running a higher grade gas is better.the 87 octane with iridium plugs were sluggish..... anyone else heard of this??

Speedy

My vote is for the NGK Iridiums. I put those in my 4Runner and it ran much better. The original plugs had 60K on them so that could be some of the noticeable difference. I run only 87 octane fuel.

mkgarrison5

is your truck all factory or do you have mods? i can understand ifyou have mods maybe switch to iridiums..