How can one go about troubleshooting occasional missing when no light or code is generated? This Sienna has 155k, and hasn't ever had a formal tune up, just good oil and air maintenance. The 3 rear plugs have never been out as they are a royal pain, but if the front 3 are an indication, they would be fine. Clean and just barely any normal wear. A complete set of coil packs might fix it, but I hate "shotgunning " parts ... Any thoughts?

  • Welcome to Motor Vehicle Maintenance & Repair! I take it you've never done the O2 sensors then, either? Ever look at the live data to see how things are functioning? Are you sure it's a misfire and not something else? – Pᴀᴜʟsᴛᴇʀ2 Aug 10 at 18:13
  • Thanks... I just very recently changed bank 1 sensor 2 for heater fail code ( I forget the code) . But that's it. The missing has been happening for months. I have a Zurich zr11 reader, but not really trained in how to read most of the live data. Would love to learn if anyone knows any shortcuts to that end ... Ed – Ed Yancy Aug 12 at 13:48
  • Here's another tidbit ... months ago, it did throw a misfire code for cylinder 4. Happened during a hard acceleration to pass. I swapped coil packs 4 & 6 to see if the code would move, and it's never done it again. Even driving hard trying to reproduce it... Thats also when i pulled the 3 front plugs and they all looked good. – Ed Yancy Aug 12 at 13:56

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