2007 Sienna was said to be fine at the dealer but when we started it she missed and shuddered and the CEL came on. Minutes later she ran fine and did so for the next day or so. Then it seemed that every other day or so the CEL would come on and sometimes misfire badly. I thought it was a bad coil and replaced one to have it run fine for a couple of days but then the problem came back. I couldn't get the problem to consistently go away by moving the new coil. Random P0300x codes no matter where I put the new coil but never any of the back cylinders until. During a deluge all of a sudden she ran poorly and I found all of these codes:
0300 Random misfire. Ignition parts, O2 sensor, EGR valve, camshaft sensor, vac leak, plugged exhaust
0301 Cyl 1 same as above
0302 Cyl 2 same as above
0303 Cyl 3 same as above
0304 Cyl 4 same as above
0352 Cyl 2 coil
0503 Vehicle Speed Sensor On top of trans
0603 Internal Control Keep Alive Memory
5203 Not found
5400 Not Found
5XXX Manufacturer specific
There was a couple a vac hoses that had cracked but I really don't know what they went to and fixing them didn't fix the problem either. She has Denso FK20HR-11 Iridium Long Life Spark Plugs
but the one I pulled looked pretty good compared to a new one. Slightly larger gap by eye but still looks almost the same as the new ones. Until the very heavy rain storm I can't remember any code specific to the back cylinders. Always the front there.
Most of the time she runs REAL good, then just on 5 cylinders but she's unpredictable! Is this enough info for a sharp experienced mechanic to diagnose a fix? I'm reasonably handy but loosing touch with these new vehicles! Happier with a '57 Chev!
What's wrong with out 2007 Sienna?