V8 Headache
 

I have a 1994 Cobra Mustang with the 5.0L v8 that has sat in a garage for the last 8 or 9 years. I have changed the gas; dropped and cleaned the gas tank; changed the oil, oil filter, air filter, gas filter, and spark plugs. I have also run the 2 part injector cleaner through it (the kind that only mechanics get). Here is the catch 22 on the car, it has trouble starting. If and when it does start it has a popping sound when I rev the engine and a black sooty substance comes out of the exhaust pipes. What is this stuff and how do I fix the engine so it starts smoothly and stops shooting the black stuff outta the exhaust. And what is this doing to my catalytic converter?

Re: V8 Headache
 

Sounds like maybe the rings are bad.

Re: V8 Headache
 

sounds like carbon build up combined with oil working past the valve seals, when an engine sits for a long period of time oil in the heads tends to leake past the valve seals and loosen the carbon build up on the top of pistons and in the combustion chamber. It is most likely getting the plug dirty, which is why the hard start and the pop (late firing of the plug). just run it at idle and check that the timing is still set and it should take care of itself

Re: V8 Headache
 

I'd go for the rings as well. If the car hasn't been started in 8 or 9 years, most likely the cylinder walls were pretty rusted and the rings probably fused to the wall. The first time you started it, I'd imagine the cylinder walls were pretty dry and the rings scored the walls. The black soot is probably fouling from fuel/oil mixture in the cylinders. If it doesn't get any better after the car has been run for a few minutes, its time to see a mechanic.

Re: V8 Headache
 

Ditto....best thing to do is pull the plugs and take a look. Then, depending on how they look, you'll probably need to pull the engine and freshen it up a bit, Valve Seals, Rings, bearings, the whole nine yards. While your in there, it would be a good time to update the pistons to some forged units, maybe a cam too. Man, I think I just spend about $1500 of your money right there! :D

Hope all is well.