i have been looking at IS engine pics, and i don't see a distributor, like you do in supra 2jzge's. did the 2jzge motor go distributorless when toyota incorporated VVTI into it, or does the IS have a distributor that is hard to see in the pic i have.
i did notice something on the front of one of the cams, that could be a cam position sensor.
Only with the use of a mechanical distributor can you have a lesser number of coils than the number of plugs to be fired. In that particular case, only one coil is needed per distributor. But the IS300 is distributorless.
To clarify, the IS300 2JZGE has 6 coils enclosed in 3 housings. Each housing encloses a "primary" coil, which connects to a plug wire to fire a plug away from that coil body, and a "secondary" coil, which fires the plug that the coil body is already sitting on.
IS300GTE: Referring back to the service manual, I'm not so certain anymore. There are three coil bodies that are connected to two plugs per. Diagnosing a faulty coil body consists of measuring two sets of resistances, the "primary coil resistance" and the "secondary coil resistance". Originally, I took that to mean that the coil body possessed both a primary coil and a secondary coil. Now that I'm scanning both the illustration and resistance values, I see that the two resistance measurements aren't parallel. And the ignition coil connector has only two prongs. These suggest that the three-coil/waste spark scenario is likely. Now looking through the diagnostics and circuit diagram book, I can confirm that there are only three coils. A cam position sensor feeds into the ECM, which feeds into an igniter, which feeds into the three coils.
[This message has been edited by DtEW (edited December 11, 2000).]