Vaccumm Leak Or Something Else Going On?

Discussion in 'General Discussion' started by Extortion, Nov 17, 2010.

  1. Extortion

    Extortion Active Member

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    2001 Ford Expedition

    bought this truck about 4 months ago with a check engine light on... i was told it was a vaccumm
    leak but the truck ran good.. the obd2 code that comes up is p0171 & P0174 (Too Lean)

    last night there was heavy rain.. idk if that could have a role in it.. but today started it up fine and drove it for about 20 min then started noticing it was missing/stumbling.. even at idle but it comes and goes.. could this be the vacumm leak just now getting worse?? or fuel related

    i had low fuel as well ....added some and it is still missing
    :confused:
     
  2. Lane24

    Lane24 technical advisor

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    Last edited: Nov 18, 2010
  3. ssbroly

    ssbroly Full Access Members

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    That's a really good link. Hopefully it's an easy fix for ya. In my case, I spent 3 weeks searching for the problem, no dice. Shop had it for 5 days and finally found that the gasket between the intake and the the block had a leak on the back side of the engine.
     
  4. Extortion

    Extortion Active Member

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    how much was that to have fixed?
     
  5. ssbroly

    ssbroly Full Access Members

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    round 700. I actually spent about 45 minutes on the phone with the head mechanic going over everything I had already checked. He was stumped too. They ended up smoking the engine to find the leak. The gasket would seal itself back up once the truck warmed up. That was the reason it was so hard to find. It just had a real bad idle when warming up, would almost stall out at times.
     
  6. Extortion

    Extortion Active Member

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    mines almost doing the opposite.. runs fine but after 20 min of driving it just starts stummbling at lights and driving
     
  7. Extortion

    Extortion Active Member

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    turned out i had 2 bad coils.. so i replaced those and all the spark plugs.. running back to normal..
    also found the vacuum leak. intake gasket needs replaced
     
    Last edited: Nov 21, 2010
  8. curleywon

    curleywon Well-Known Member

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    I'm having a similar problem. While in GA, I replaced an extremely dirty air filter then drove the truck back to Baltimore. The truck ran ran fine on the way back an I even notice smoother acceleration. The next morning I start it up and the check engine light comes on and it is idling horribly. I drive the truck and it drives fine but nearly stalls at every light. I disconnect the battery and the check engine light goes out, but the problem persist. I get new plugs and wires thinking that will solve the problem. That fixes the idling problem but a new problem arises. When cruising at any speed and the engine RPM's drop below 1800, if I try to accelerate gradual, the engine stutters. Either flooring it it letting off the gas a bit corrects the problem, but gradual acceleration will produce stutter until the RPM's get above 2000. Could this be a combination of a vacuum leak and bad coils? I was thinking fuel related, filter, injectors etc.
     
    Last edited: Nov 22, 2010
  9. walnuts4x4

    walnuts4x4 Supporting Member Supporting Member

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    I'm gonna say vaccum before fuel problem... when I had a similar problem mine was the 90 deg elbow on the PCV hose.... check that first simple and cheap then look for more $$$ problems
     
  10. Extortion

    Extortion Active Member

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    This is exactly what happened in my Caprice & Roadmaster..
    Driving Fine Til about 45 mph.. letting off the gas or flooring it stopped the sputter.. it was Injectors going bad.. Hope That Helped a little
     
    Last edited: Nov 22, 2010

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