Engine Smoking - Problem explained, Need Help

[1qwikspyder]

Background: About 3 weeks ago I was running a lotus elise and after the run I was noticing white smoke coming out the hood and exhaust. I pull over and get the car towed to my house. Do a compression test on it and all the cylinders are fine. We figure it's a headgasket so we take the head off get it decked, pressure tested, vac tested and they checked the valves and say that everything is fine. We also replaced the old headgasket w/ a new cometic and also put arp headstuds in it. Well we put it back together last night and it's smoking even worse now. We let it idle forever and it didn't stop so something was wrong. We turn the car off and begin taking out the spark plugs. We take out cylinder 4 spark plug and smoke begins coming out of the hole. So then we take out the rest and no smoke out of any of them. We begin thinking something is up w/ cylinder 4 so we put all the spark plugs back in and start the car back up and unplug the #4 spark plug so the car is running on all the other cylinders and it's still smoking. Thing is, the number 4 cylinder seems to have good compression because when the cars running w/ the spark plug out it's blowing good pressure out the spark plug hole.
This is where it gets weird. When the spark plug is out and the cars running no smoke comes out the spark plug hole however, when the car is turned off the smoke begins to pour out the spark plug hole.

What i've done: I've taken off the exhaust manifold and looked down the runner and the #4 cylinder's valves are cleaner than any other exhaust valves from any other cylinder. They are basically shiny. Also, they seem to be alot lower. All the other ones you can see the bottom of the valve through the exhaust runners, however on cylinder 4 the valve is further up in the head to where u can stick your finger into the cylinder.

What could this be? What should I do to get more info on what it could be?

 

[anconover]

You said compression was fine? What was the compression results then. Thatll be of more help. Does it smoke out of the oil cap if you pull it off?

Check compressor housing for oil/residue as well as the turbine housing. Make sure the pcv isnt plugged etc.

 

[bullettdsm]

Possibly injector. Quick check, switch injector and see if problem moves with it.
MB

 

[BlknBlue2G]

When does the car smoke? Under boost or at idle. What color is the smoke? Did you replace the valve seals when the head was off?

Or maybe you figured it out already.