Spark Plugs Options

[phokur]

My Celica is starting to sputter every once in awhile while in 5th gear at about 3grand or so. I'm pretty sure it's plugs. Can anybody recommend any plugs?

[alltracman78]

Here's the deal.
To start, MOST newer [say 90^] factory turbo cars use platinum plugs because turbo engines wear plugs faster, and the platinum lasts longer.
Manufacturers want longer service intervals. Sells more cars [they can advertise cheaper maintenance costs].

3SGTE is platinum stock.

I have no clue why your friends say iridiums are bad in a 3SGTE.
They are wrong. Period.

Too many Celica guys run them with no problems, and have even had them solve problems, for them to be no good.....
And stock is platinum. Not copper.

If by Direct coil you mean DLS [DistributorLess ignition System], EG late Camry 5SFE, 7MGTE
Either copper or iridium. I guess depends on your taste and wallet.
As someone found out, iridiums are quite a bit more expensive than coppers. But they also last longer. Obviously NGK or Denso.
If it's turbo and you've bumped the boost up a bit, I would run a step colder than stock plugs.

If it's DIS [Direct Ignition System] with stock ECU, I would stick with what the recommended plug is. Otherwise you run the possibility of setting the CEL. Not the end of the world, but a PITA.
A colder plug shouldn't matter, but at least if it calls for twin ground, use them.

However, stock 2JZTE uses DIS, with twin ground.
I don't know what the Supra guys run, with what results.
Obviously only stock ECUed engines would matter for this.

If it's a aftermarket EMS, I guess the same as DLS. It shouldn't have the same feedback system as a stock ECU.