I have a 1990 Camaro RS V8 305 and I was driving last night to my gf's house, it was very cold out and I hadn't let the car warm up entirely and I was being a bit rough on the car. As soon as I got to her house I saw smoke coming from underneath the hood of the car, I think there normally is a little bit of smoke but because it was so cold I noticed it. I opened the hood and smoke was coming from the driver's side of the engine bay, I looked closer and it looked like it was coming from the little pipe that connects from the snorkel of the air cleaner to the top of the driver's side exhaust manifold, i saw traces of oil also, I burst the little metal piping that connects the air cleaner to the exhaust manifold a long time ago and didn't see the need to fix it, I also saw traces of oil on the little pipe, the exhaust manifold, and on top of the valve cover, what could this be? the car runs fine, the oil pressure is good and the oil level is fine.

 

there should not be oil in the TBI snorkle. And that hole mearly takes the head coming off the driver side header, and transports it into the intake to heat up the motor faster, once the computer reads that the car is warmed up, a valve that is vacuumed controlled closes where that hose comes from so that "only cold" air comes in. Should it wasn't water on rust in the dark that made it look a bit dark and thick? Did you look at it in the day time?

Also have you considered a leak in your y-pipe maybe? I know my y-pipe is starting to rust there and i have an exhaust leak so everytime i fire it up i get a little plume of smoke. Usually just from the start up and it goes away.

 

I think it's very possible that it could be water perhaps, that side usually does smoke a little bit because i spilled a bit of oil on the valve cover when i changed the oil and never cleaned it off, but it was a considerable amount of smoke, it was coming out from underneath the hood with it closed, i'm sure that because it was so cold out it was very visible but it sure did seem like alot of smoke, it looked like it all was coming from that cracked little metal pipe that runs from the air snorkel. you say that the purpose of that little valve is to block the air snorkel from delivering cold air to the exhaust manifold while it warms up correct? if so is it possible that it's merely exhaust flowing out of that valve?

 

It is probably oil leaking from the valve cover onto the manifold. Did it smell like burning oil?

 

exhaust could be leaking into the intake if your headers were that rotted. Otherwise it's purpose is purly pulling hot air from around the headers to head the block faster, much like the radiator lines running thru the throttle body of the TPI or LT1 systems. Purely just to warm it up.