Vacuum Question (Pic inside)

Discussion in 'Fox 5.0 Mustang Tech' started by asecretfile, Aug 2, 2008.


  1. asecretfile

    asecretfile New Member

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    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

    thanks
  2. Johnny P

    Johnny P New Member

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    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. asecretfile

    asecretfile New Member

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    well Im getting crankcase vacuum even with the manifold vacuum to pcv removed

    :shrug:
  4. Johnny P

    Johnny P New Member

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    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.

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