distributor on '99 camry?

No distributor.

Each "funny box" is a coil feeding 2 cylinders -- both get spark at the same time, one has compressed air/fuel to ignite, the other is at the end of the exhaust stroke, so that spark is wasted.

All computer controlled (of course)

If you use your e-mail address in a newsgroup you are just asking for tons of spam.

Thanks!

Any seals to wear out...? Are they tied to the camshaft?

Yes, I know. I made the mistake once of posting with my real email (groups.google makes this mistake really easy to make), instead of my spam collector, then just decided to give up maintaining two email systems.

Google mail does a good job of segregating junk mail, though.

Michael

Yes, that generation uses the waste spark system. That's why the Bosch Platinums with the thin center electrodes should not be used on the waste spark system. The deposits from the ground electrodes stick to the center electrodes and foul up the plugs, even though the plugs work well and reach self cleaning temperatures fast in traditional systems.

The current passes one plug from the center to the ground electrode and then through the cylinder head to the other plug in the loop; it then goes from the ground electrode to the center electrode on that plug; finally the current makes its way back to the coil thus completing the circuit. The spark plugs fire at twice the ignition rate, halving their useful life.

The waste spark system stinks. So Toyota changed back to the traditional system. It helps not to have plugs with half the service life of your competitors' plugs.

snipped-for-privacy@gmail.com wrote:

So using Bosch plugs would do what - short-circuit the electrodes, and fail to ignite, resulting in loss of power...?

I've been using Bosch dual-platinum plugs in my wife's '99 camry, no problems so far - been about 5k miles so far. I'm open to changing the spark plugs (myself) more often, if necessary - no problem. I think I paid about $2.50/plug (Bosch). Just, $13/spark plug (NGK) is a bit much, I think. Even if I have to change out the spark plugs 4x as often as the NGKs, I'd still come out ahead financially.

Assuming no engine damage due to the cheaper plugs, of course.

Thanks,

Michael

The nickel from the ground electrode gets transferred to the center platinum electrode with each spark (the platinum gets a nickel plating). This reduces spark efficiency. But if yours work then I guess no problem, the Bosch x2 with thicker center electrode is better than the single ground electrode one. Bosch plugs reportedly work great in their Motronic engine control systems, the first series-produced digitial engine control system in the world.

I don't use the NGK $13 double ground spark plug. No way $$$. And definitely no Denso spark plugs. I use the NGK Iridium from the local NAPA store for $7.99. I change them at 30K miles. You get NGK's thicker "Laser Iridium" with platinum ground electrode $9.99 for 60K mile service in waste spark systems (120K mile in traditional systems). I don't believe in the 60K or 120K mile spark plug interval. It's my personal preference to change them at 30K miles.

That was only what I heard about waste spark systems. Haven't tried anything else since I started on NGK Iridiums. But you're right, if Bosch x2 works for you, at $2.50, go for them.

Oh ok. As long as no major engine damage would result... ;-)

I was tempted to try the Bosch 4-electrode plug... that one looks really pretty.

Ooh, $8/plug! Much better than $13/plug. (At first, when I bought the $13 plugs, I thought that was for a set of 4. Imagine my surprise when the total bill with tax came to about $60. When I came home, the wife chewed me out, and I returned the plugs a couple days later. ;-)

You'd think that with a computer-controlled ignition system, Toyota could figure out how to make one spark plug fire at a time... sigh.

Thanks for the info

Michael

Well I guess the Bosch platinums work OK in waste spark systems, at least better than the early years.

The Bosch site does list these plugs (Platinum x1, x2, x4) for the application so it's OK. The Iridiums electrodes are simialr to the Bosch thin platinums (therefore both should be able to fire lean mixtures and reach self cleaning temperatures fast), except the Iridium electrode is not wrapped by the insulator tip like Bosch's. The Bosch x2 and x4's flame fronts spread flat out toward the ground electrodes and face the entire combustion chamber unobstructed. Multi side-electrode plugs are better in this regard.

4303 PLATINUM 2 Do not gap. Gap is not adjustable. 4201 PLATINUM GAP=0.044" 7556 SUPER GAP=0.044"; Original equipment is platinum or other precious metal. 4417 PLATINUM+4 Do not gap. Gap is not adjustable.

Yeah, I know, but the Iridiums are fine plugs, and before that I almost used the NGK G-Power platinums. But I guess I'll try the Bosch platinums x2 or x4 next time both have thicker electrodes than the x1. Thanks.