Guys,

First off, alright, alright!...it's a FORD, a 04 Ranger 3.0. My 16 year old neighbour across the road owns it. It's in very nice shape. He's young fellow without a dad that really wants to be a mechanic, and is very eager. Just needs a little help and maybe a bit of mentoring. Perfect for a old retired guy mechanic wannabe. I enjoy helping him. It's amazing how many little things and tricks we acquire and store in the back of our minds over the years that are nice to pass along.

Anyway, the truck Just recently it started running rough on a trip and the check engine came on. Still drove fine, just rough. But no mechanical noises. No ticks, rattles, super quiet even with the miss.

Had it scanned at the dealership he co-op's at, got a check engine and a misfire detected in Cylinder #4, and Misfire detected at startup.

Pulled the plugs last week and all the but #4 were absolutely perfect.

#4 was really bad. Not good. Very worrisome that it was missing the center electrode!! Is this mechanical damage? Changed all the plugs.

Still running poor. Played with the wires, no change.

Pulled #4 plug for a compression check today. Dry test, no compression showing, zilch!

#3 cylinder adjacent...120.

What do you guys think? Bad intake lobe? Exhaust valve regressed and open? Valve stuck in the open position? Compression rings gone?

The fact the needle on compression gauge needle barely moves I feel eliminates a ring issue. Even with bad rings you'd still get a minor pump up... right? It's like there is no air in there, like the intake valve is not moving. I don't think it's a mechanical failure such as a broken piston, but who knows.

I have a scope and will have a peek in #4. Maybe see the valves as they move, the bore wall condition?

Any ideas to help the kid along?