My car was smoking from the back of the engine, and leaking oil all over underneath. and then i took the keys out of the ignition and it wouldnt shut off!

Their must be some oil stored somewhere and it is dripping on your exhaust manifold,but never pressure wash your engine, could cause worse problems,in time the smell will go away,just be patient.It will burn off in time.

and oil level on engine is full?
was that smoke oil smoke or steam,?
no matter, id do a compression test on it,
if the engine (unstated type) is interference engine
id do a leak down test by hand, so as to limit further damage.

for sure engine leak oil (what about 1/2 on the road)
and for sure if said leak , travels by wind or gravity, lands on the
exhaust PARTS, it will smoke and burn.
fix leak, stop burn.

It can easily burn that much in a 100 miles without seeing any smoke.
If you check the spark plugs you may find evidence.
It can also leak while the engine is running and not when it is off. Most Northstar engines leak to some degree.

There are two main causes for this, especially given your limo's age:
- a leak, and you would notice little puddles of oil underneath the car
- worn piston rings - this will cause blue smoke from the exhaust, especially after idling for a few minutes
Have someone watch at the back, when the engine is hot, and after idling steadily for a few minutes, rev up suddenly to 2000-3000 RPM.
If you get a big cloud of blue smoke, the engine is worn.

For the smoke to occur in the engine compartment it has to be something that occurred external to the engine or an external leak from the engine. White smoke would have been steam and suggest a blown gasket that allowed water to exit the engine. Assuming it was not something that burned it would point to a leakage of oil or perhaps a belt. Two things I would check are the belts and the engine compression. An external oil leak on a hot engine could have made the black smoke and may not show up when the engine is cool. If it is an oil leak you may be able to find out where by putting some paper under the engine and turning the engine over enough to create a drip on the paper.

Also try to remember if you smelled anything when the problem occurred.

This will take your question of the help page so if this doesn't lead to to anything make sure you repost.

Get a Trouble code free at Autozone or similar store. It may be the catalytic converter thats bad.

There could be several reasons, here's a list of the most common things it could be.

1. check the timing
2. idle speed is to high
3. incorrect spark plug heat range
4. intake air vacuum leak
5. valves sticking
6. leaky fuel injectors

are u getting any white smoke from the exhaust? it could be a water jacket leaking which means it wouldnt neccessarily show up in the oil.

Plugs wont be able to *ignite* the oil, however the heat of the engine will. You need to find where the oil is leaking from and fix that problem.