gap twin electrode spark plugs ?

[ycl1688]

I bought a used 2001 four runner, found out the previous owner
has dealer installed spark plugs, when I took out spark plugs and
check the gap it was way too low for manual instruction for .043 inch
gap, is it necessary to replace those twin electrode spark plugs and
gap with manual instructions ? the dealer installed in dec 2002.

[ToyotaTech1]

You should replace the plugs every 30k miles, they come pre gapped when purchased from toyota if you look under your hood it says do not gap plugs. I would suggest putting a new set on there maybe they dropped one and it closed in.

[ycl1688]

It was NGK spark plugs installed by dealer.
Now I bought from autozone also same
NGK exact same spark plugs, gap is way too
low from manual recommendation ?
what give ?

[Brian R.]

If the plugs you bought are the same part number as those recommended for your truck on the sticker under your hood, then gap both the electrodes to the recommended gap.

A possible reason for the discrepancy is that the plugs recommended for your truck are also used in a different engine, or different application with the same engine, and the gap you see is recommended for the alternative application.

[ycl1688]

i just got a message from ngk technician, they
said not to gap, it comes with pre set from
factory. When I check the new plug I bought
it is way too low. I check the gap between
the electrod and the center piece.

[ycl1688]

The dual ground style spark plugs are preset at the factory. The gap your checking I assume is between the center electrode and the ground electrodes. This is an intermittent discharge style and the gap is preset between the bottom of the ground electrode and the insulator.

The above is reply from NGK, does it make sense ?

[Brian R.]

No. There is no reason I can think of to set a gap between and electrode and an insulator. The reply came from someone who didn't think about it at all.

Maybe, just install the plugs without bothering to gap them, and if your engine runs well, don't worry about it.

BTW, the recommendation I gave above about regapping the plugs if the part numbers were the same came from my local Toyota dealer...

[ycl1688]

anyway ngk web site says not recommending
setting gap for double grounded spark plugs

[Brian R.]

Yet there is a specification for gap. Why bother if you aren't supposed to check it?

[Brian R.]

Why don't you see what Denso says. They also make a plug specific for your engine...