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  1. #11
    Old Timer jeeeep's Avatar
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    Oct 2011
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    Tx
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    4,167
    use a long screw driver or go to harbor freight and get a Mechanic's Stethoscope for $4

    have someone start it and shut it off while you have the end of either a screw driver (other end at your ear) or the stethoscope on the booster.

    you'll be able to hear it clearly if it's the booster or check other components until you narrow it down.

  2. #12
    Fresh Catch Pixel's Avatar
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    Aug 2015
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    NJ
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    35
    Last night I was able to find some time to do some testing and maintenance. Ran the BG EPR and BG 44K products through it as directed and then changed my oil and filter. I was going to do the Mopar combustion chamber cleaner as well but didn't have anyone to keep the idle up for me while I sprayed in it. Took it for a drive and it ran ok.

    Today the P0302 code came back. Just out of curiosity I pulled the plug and it was oily (Changed them in January about 4,000 miles ago when I changed the coil, plug, wires, and O2 sensors) The gap also opened up slightly as well. I put a new plug in and gapped it correctly. Still running extremely rough at idle and when trying to go above 40mph this thing rattles like hell. I had a friend around today so I figured I would try the MCCC today as well. After driving the vehicle around for a bit to get it up to temp I attempted to spray the can in while maintaining 1000-1200 rpm I couldn't even get the throttle plate open at this rpm range. At 2000 rpm the plate barely opened up enough to squeeze a quarter in. Is this normal? It is the first drive-by-wire vehicle I have owned but I know not to force it open so I didn't.

    Any ideas how far the OEM 3.8L throttle opens up at specific ranges?
    Could I possibly not be getting enough air in?
    Could this cause a misfire code?

    So many questions. I have attached a few pics of the original plugs I pulled a few months ago as well as the numbers from the cylinder compression test. I did notice the #2 plug was actually pretty dirty back then too. Didn't think much of it at the time.

    maintenance-2017-01-14-compression-test.jpg
    maintenance-2017-01-14-sparkplugs-pside-01.jpg
    maintenance-2017-01-14-sparkplugs-pside-02.jpg
    - '04 TJ (Sold)
    - '07 JKU (Driving me slowly insane)

  3. #13
    Fresh Catch Pixel's Avatar
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    Aug 2015
    Location
    NJ
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    35

    Fuel Trim

    Recorded some data of the fuel trims also.

    https://youtu.be/osejGgwTJS4

    https://youtu.be/ur-oupZLud4
    - '04 TJ (Sold)
    - '07 JKU (Driving me slowly insane)

  4. #14
    Knows a Thing or Two Judesign's Avatar
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    Mar 2015
    Location
    San antonio
    Posts
    607
    Your fuel trims don't look too bad but they are out of spec especially your bank 2. Generally when the combined numbers of long term and short term are over 10 then you have an issue. It looks like your oxygen sensors are correcting for the most part (short term fuel trim corrects to a degree). It also seems to correct more under throttle which would indicate a vacuum leak. Not sure about the throttle plate but your fuel trims show you running lean (too much air) as opposed to rich. The relative compression test looks good. Oil on the plug could be worn valve guides or seals, but hopefully not a head gasket as your compression test looks good. Hopefully someone with more knowledge here will chime in. Hope you get it figured out.


    Sent from my iPhone using WAYALIFE mobile app

  5. #15
    Fresh Catch
    Join Date
    Nov 2016
    Location
    Costa Mesa California
    Posts
    20
    Quote Originally Posted by Judesign View Post
    Your fuel trims don't look too bad but they are out of spec especially your bank 2. Generally when the combined numbers of long term and short term are over 10 then you have an issue. It looks like your oxygen sensors are correcting for the most part (short term fuel trim corrects to a degree). It also seems to correct more under throttle which would indicate a vacuum leak. Not sure about the throttle plate but your fuel trims show you running lean (too much air) as opposed to rich. The relative compression test looks good. Oil on the plug could be worn valve guides or seals, but hopefully not a head gasket as your compression test looks good. Hopefully someone with more knowledge here will chime in. Hope you get it figured out.


    Sent from my iPhone using WAYALIFE mobile app
    I have a 2007 Jeep Wrangler Rubicon we just had to have the crank sensor replaced Ours had a rough time starting sometimes and idling seems to be doing better now


    Sent from my iPhone using WAYALIFE mobile app



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