My Car Won't Run
 

I need some help guys. I own a 96 Mercury Cougar with a 4.6L V8. The car is running very rough, i have changed the spark plugs and the wires and it's running even worse now. I noticed when I cahnged the plugs on the right side of the engine they were black. What could this mean? Any suggestions are welcomed.

Re: My Car Won't Run
 

Black and dry or black and wet?

Check engine light on?
Any cracks in vacuum tubing?
This engine have a dist or dist-less ignition?

Re: My Car Won't Run
 

It has coils and the plugs were black and dry.

Re: My Car Won't Run
 

My first guess would be carbon fouling (usually caused by an over-rich air-fuel mixture).

Tell us a little more about the engine. Does the intake manifold use a common plenum, or does each bank get it's own? One fuel rail per bank? TBI?
I'm taking stabs here, but you never know when you might stumble into the right answer...

Re: My Car Won't Run
 

I'm not quite sure what your asking. I work on the outside of cars not under the hood.

Re: My Car Won't Run
 

Fair 'nuff. TBH, I'm not all that well-versed with the finer points of modern engines ;)

Where'd I lose you?

Re: My Car Won't Run
 

I know what the problem is...its a Ford :p

To be honest I'm not that much of a car person so I'll just sit here with a notepad and take notes from the wisers. :)

EDIT: If you love cars that don't run right then I see why you love Fords :lol:.

Re: My Car Won't Run
 

You lost me at the fuel plenum and rails. BTW I love my Ford

Re: My Car Won't Run
 

Old Ford Syndrome is a very real affliction ;) Trust me; I've got a '77 Ranger with a 460.

Ok then: how does air enter the engine? On most vehicles, there's a single air intake somewhere that feeds into a chamber (the plenum) atop the engine. Typically, this part of the intake is more or less a common area to all cylinders, but not necessarily always. Since I don't know offhand how 4.6L Ford was designed, I thought I should make sure.
Fuel rails exist on port-injected engines. They're basically hollow pieces of metal that the injectors tap into, and all they do is feed fuel to the injectors. They look just like a metal tube running the length of each cylinder bank. Every port-injected system I know of is considered to be "dry", where fuel is added to the intake charge only as it enters the cylinder.
Throttle body injection (TBI) moves the injector(s) to the throttle body itself. This is considered a "wet" system, as the fuel is added to the engine as soon as air enters the engine (carbureted engines are also wet).

If you've got four clean plugs on one bank and four dirty plugs due to carbon deposits on the other (which sounds like that you describe), then the side with fouled plugs is receiving too much fuel. That's why I'm wondering how air and fuel induction is being handled with your engine.

Re: My Car Won't Run
 

Ok i think I understand now. There is only one intake and i don't believe there is any fuel rails.