Love the performance of the new 351 but have been chasing a couple issues and looking for advice

At about 150 miles the check engine light came on, ran it that way for another 50 or so until I got a code reader. #8 mis-fire was the only code. I can erase the code but it returns whenever the engine is to temp and has any load beyond idle. Can't really feel a run issue but the code keeps popping up.

I also have a small leak at valve cover, right at back of head above #8. When I removed the upper intake to get at the valve cover I noticed more oil than normal in the #8 runner of the upper intake. A little in #7. Cleaned it up and tightened up the valve cover and stuck my head back in the sand.

Swapped a couple plug wires around to determine if the #8 wire was the cause of the code. Code remained at #8 so wasn't the plug wire. Pulled the plug, it looked a little oily / fuzzy on one side and clean burn on the other side of plug. Cleaned it up and swapped plugs between 7 & 8. Code keeps coming up.

Have run it this way for a another couple hundred miles continuing to monitor codes, etc. # 8 misfire was only code until today. I also got "no DTC definition detected", whatever that means.

Meanwhile, valve cover still leaking so I decided to swap to another type of gasket. When I removed the upper this time there was even more oil in the upper intake. #8, 4, and 7 all had oil but everything else bone dry. #8 had about 2 teaspoons and 4 & 7 probably about 1 teaspoon in each. #8 plug kind of dark / oily for a plug with less than 500 total miles on it (200 since having cleaned it). See the pics.

So, where the hell is all of this oil coming from ?

You know this is going around full circle to a compression test. Good thing you didn't use P heads. Oh wait, you did.

Comp and leak down tests will tell you alot.

How is the PCV setup run? My thoughts are leaning toward some excess oil coming in from a weak PCV valve. Underlying cause of that........
HTH, Joe

What did you find?

We reconfigured the PCV routing as mentioned previously to allow the excess oil to drain back.

We also added a big baffle to the underside of the upper intake. This should help reduce the amount of oil being pulled up through the PCV to begin with.

Also, yesterday Garry did some additional tuning to counter an IAC code I kept getting.

We could see a slight miss and the left bank was running lean.

Whatever adjustments he made were perfect because it runs like a champ now !

What iac code? I kept throwing p1506 iac speed codes. Every down hill it tossed a code.

I'll try it...Cheap fix (if that does it!). Thanks!