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HELP! 04 4.0 Rough idle/ Misfire?

Discussion in 'Stock 2002 - 2005 Explorers' started by NE2004elpXLT, September 20, 2011.

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    1. NE2004elpXLT

      NE2004elpXLT Guest


      I have a 2004 Explorer XLT Sport with a 4.0 V6. I recently did a bunch of work on it including:

      replaced front differential fluid w/ Mobil 1
      replaced transfer case fluid w/ Mobil 1
      replaced rear differential fluid w/ Mobil !
      new Motorcraft air filter
      ATTEMPTED to replace fuel filter without success
      flushed and filled coolant
      new Motorcraft Plugs and Wires

      It was running like new for the first 100 miles or so, now it idles rough, stutters when accelerating from idle, and the "service engine soon" light came on.

      I scanned the OBD II computer and it came back with:

      P0171 Bank 1 system too lean
      P0174 Bank 2 system too lean
      P0300 Random multiple misfire detected
      P0316 Misfire on start up

      Anyone have any ideas? I don't know where to start. Thanks!
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    3. matt0248

      matt0248 Active Member

      July 12, 2010
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      02 XLT V8
      does it get better after it warms up? sure sounds like leaking intake manifold gaskets to me.

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