Vacuum Question (Pic inside)

Discussion in 'Fox 5.0 Mustang Tech' started by asecretfile, Aug 1, 2008.

  1. ok so upper to lower gasket wouldnt do that but lower to block gasket might?

    any test I could perform to verify before tearing it down? Ive tried the carb cleaner method but its tough to get a spray on lower to head

  2. I just completed a baffle swap on the lower intake (cobra) because I was getting alot of oil in the upper (3 litres after about 300 miles) my plugs were foulled and the car ran as if on 2 cylinders, the car also ran pig rich and could not hold an idle. ford racing sent out the new baffle as well as gaskets. Now I find oil consumption is not an issue but after reading this thread I checked out my oil fill nipple and there is vacuum going into the valve cover. This may be the reason I was getting so much oil before, vacuum into valve cover, excess vacuum out the pcv, enough to carry plenty of oil with it. When I completed the swap the car felt perfect all around and idled perfect. After a few days I noticed the car now struggles/hesitates to build power up to 3K rpm and hunting idle / ocassional stalling has come back. I don't think there is a leak in the lower, not after 2 installs. is this possibly the only solution / reason?
  3. well Im getting crankcase vacuum even with the manifold vacuum to pcv removed

  4. new to this site, hope you don't mind me throwing in my 2 cents. I have the exact same problem and after trouble shooting and replacing parts/sensors I'm at a stand still. I think Joels right, you MAY have a vacuum leak on the lower intake to lifter vally side.