Iridium spark plugs or platinum?

WOW. ... SERIOUSLY?!? ... LOL.

 

yeah seriously...unless you live under a rock counterfeit auto parts are a big money making thing.

 

With the long recommended interval for changing them at 120k miles, saving a couple of bucks a plug buying them online seems crazy if a Toyota dealer is nearby, which is common.

 

It turns out I spread some misinformation earlier about the misfire margin. It is a number the ECM is constantly recomputing while the engine is running, and its normal range tops out at 100. Whenever the engine is not running, this PID sits pegged at 127 (which is normally not a valid value for it). So it's no use to just go ask "what's my misfire margin?" and get a single number, which'll just be 127 if you're asking when the engine is stopped. It doesn't somehow summarize the whole drive you just made.

It is more useful to datalog and graph the misfire margin, over a short drive that takes in various driving conditions. If you're using Techstream, you can graph several things at once, like coolant temperature, RPM, engine load, EGR %, and misfire margin, and look for where the margin gets lowest, and what the other engine conditions were at that time.

For what it's worth, misfire margin wasn't new for Gen 3; I checked in the Gen 2 repair manual and it's in the Gen 2 data list also.