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05 OHV P0316 P0301 replaced coil etc

Posted: Thu Feb 16, 2017 3:36 pm
by bspurloc
I'll start this off by noting, I truly dislike this Car and its Engine.
I do all my own auto work and this car is my greatest dislike.
So anyway point is, I have quite a lot of experience working on engines and all things to do with cars.

This is a relatives car. a year or 2 ago it was doing the multiple misfires, followed by the LEAN Banks which eventually come from misfiring. So the car having 90,000 miles, I replaced the Plugs, wires and air filter. They all looked fine. It was still misfiring, but got through emissions before throwing another code.
Cylinder 1 is fine, that tends to change, P0301 is just what its complaining about this time as P0300 is lit also. Multiple Misfires.
The car does not have drive ability issues. I can hear its running rough at idle where others wouldnt notice it. Gas Mileage is on par.

So I looked at it again, I replaced the coil without checking how far each cylinder could jump a gap. I replaced the PVC valve left side. Cleared the codes. It was still running rough. a few months later light back on due to LEAN Banks from Misfires.
Now I pulled the PVC valve off cleaned it and the o-ring, pulled off the Tube going from it to the intake cleaned that all up. I checked the COIL I had on and the lower 3 didn't seem to be jumping as far, so I warrantied it with another which seems all 6 are good. I sprayed carb cleaner all over the vacuum lines, all over the intake, all over the egr and pvc area, all over the intake and absolutely no change in engine rpm. as in I did not detect any air leaks at all. I cleaned the MAF which wasn't dirty.
The spark plug wires are all isolated from touching anything metal and show no signs of arcing. you hear nothing arcing, in darkness u see nothing arcing.

After cleaning everything up, and doing numerous leak checks and finding, nothing I cleared the codes again. I can hear it idling rough. Took it for an aggressive ride, check the PCM. I show pending codes Multiple Misfires and Multiple misfires on startup. Grrrr.
I am totally at a loss as to what to look at next.
Like I said, the car has no drive ability issues. so I am not apt to think its a faulty Cam Position sensor or Crankshaft Position Sensor. any way to test this? so hard to get to them. annoying.
If it were a leak at the intake manifold, where does that usually happen? it is kinda hard to spray carb cleaner at the back area, but I think I got it done.
The car has been garaged all its life so there is no corrosion issues.
Is it possible this needs that PCM Update I have read about to resolve this problem? is there a Bulletin for that update?