I noticed the camry manual says to use twin-ground, platinum-tipped
spark plugs.

Is there a significant difference in performance between using, say,
Bosch (Pep Boys brand) vs. the original NGKs?

And is there a real difference in performance between twin-ground vs.
regular plugs? (For that matter, Bosch has a plug with 4 grounds... is
this better?)

Paid $13 per spark plug for NGKs, now I'm wondering if Bosch
twin-ground platinum plugs at $3 each would have been just as good.

Yes it's different. The reason is for the waste spark ignition system
used on the Camry. This is an old GM design that allows for the savings
of 50% of the coil-on-plug's. But the disadvantage is the spark plugs
fire at twice the rate of non-waste-spark systems and the plugs live
half as long.

went back to the old non-waste-spark system.

electrode(s); on the other plug the spark jumps from the side
electrode(s) to the center electrode.

Therefore, you should not use the Bosch plugs on any waste spark system
cars. This is because when a spark jumps from the nickle plated side
electrode(s) to the thin platinum center, it carries material with it
and covers/fouls up the thin Bosch center electrode.

The Bosch plugs, however, work fine otherwise because it spreads the
flame sideways across the center insulator towards the ground
electrodes on the side. A nice clean big unobstructed spark.

In general, these engines work best on NGK or the cheaper Denso (if you
think the NGKs are pricey). Something about matching the heat range or
such. I dunno. So go to Autozone and buy Densos at about 1/2 the NGK
price if you like. But NGKs are better, longer lasting plugs that don't
look like crap at the same miles. But I'd still replace any plug at
30,000 miles.

Both NGK and Denso list Iridium as acceptable replacements even with
just one electrode! Excellent plugs, clean burning. Wanna try them next
time?


onehappymadman@yahoo.com wrote:

I thought only the '98 had the waste spark system. '99 camry has it
too?

johngd@hotmail.com wrote:
"So go to Autozone and buy Densos at about 1/2 the NGK
price if you like. But NGKs are better, longer lasting plugs that don't

look like crap at the same miles. But I'd still replace any plug at
30,000 miles."
When I replaced the ND platinum at 60,000 miles they still looked fine
and the gap was exactly where it's supposed to be, so I'm not sure why
you're replacing them at 30k. Iridium can go 90.

Daniel wrote:

I guess I could get the $3 Pep Boys plugs, and change them every 20,000
miles: that would be the equivalent of spending $9 per plug at 60,000
miles. (Ignoring my free labor to change the plugs.)

Still cheaper than buying a $13 NGK plug and changing at 60k miles.

Sounds like a plan? :)

That's why I say Densos will look like crap but NGKs are better. 90K
iridiums use a platinum padded ground electrode with a heavier center
iridium electrode. Doesn't cost $2-3 more each. But don't drive the
regular iridiums to 90K!

I'd change them at 30K because I notice slight low-end performance
degradations. NGKs should be good for 60K. But that's pushing the
limit. In my experience, the 90K or more intervals were a result of
marketing than engineering. The plug tips and gaps may look fine, but
they don't work as well.

I would not go with Bosch on that engine for the reason I mentioned
about the waste-spark system.

But if you are willing to change at a more frequent interval, which is
fine for a 4-cyl engine, piece of cake. Then go with NGK G-Power
BKR6EGP with the thinner platinum center electrode. Toss them every 15K
miles for $2.85 a piece (froogle.com price).

The BKR6EGP plug, by the way, is an approved application by NGK catalog
for the engine.