Originally Posted by Jgrove998
You will get the greasy build up on the throttle body because of the PCV system. Which hose is split? The PCV valve is behind the intake manifold which is why it costs so much to replace it. The PCV valve is very simple with not a lot to go wrong. Mine even held up to boost before I removed the system completely.
The hose that goes to the valve cover carries already metered air into the top of the motor and the air rejoins in the intake manifold so if your venting already metered air that could be playing into your bad mileage.
I would recommend the plugs (which you've done) and a fuel filter change. I have never got less than ~25 mpg since I started driving my first '05 Focus back in 2007. My ST even got over 30 mpg highway with the turbo on it.
The hose I noticed can be viewed through the opening through the intake manifold on the right side, behind the manifold. It connects to a black plastic piece at a 90* angle from the hose. I believe that is the PCV valve I am looking at. The hose appears to be completely collapsed and is split open like a hot dog on the top.
Is there a way to replace just the hose without removing everything else to get down in there? I also need to find a place to order the parts I need, because there is no way I am paying almost $500 to have someone else do the job.