I have seen 3 p219a codes come in on 1gr motors in the past month. p219a-bank 1 air fuel ratio imbalance. I have repaired 1 so far, I am having a hard time diagnosing this other one. I want to hear other guys experience with this code and what ended up being the issue... any help would being greatly appreciated

 

My thinking since I have zero experience with this model, is to try cheapest things first. I'm assuming this is a V6 so you can swap all injectors and ignition components from side to side to see if it moves. Now I'm guess but does this have two cats? If so swap them side to side along with O2 sensors. Keep in mind it might be a marginal condition with no one part being the whole answer. watch your Pids to see if fuel trims change.

 

I use a techstream and I can monitor both cats, both 02 sensors and, both a/f sensors. These are not the issue. There is a speed variation on cylinder 1, 3, and 5, which are all bank 1 cylinders. Also just replaced oil control valves on bank 1 for vvti. it seemed to get better, then the code came back. I am thinking vvti malfunction. this vehicles repair history had oil starvation due to a mistake made in the past. I am going to do compression and leak down again to see if i missed something... I will keep you posted

 

Speed variation plus oil starvation says the pistons may be wiped and are dragging on the walls, or a broken upper piston ring that stuck for a split second. You are right about VVTi Do you have a bore scope that can go into the cylinder from the spark plug hole? Have you tried putting an upper cylinder lubricant into the oil and perhaps spray some into just those three holes?