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    #1

    Weird engine behavior?

    I've noticed this happening these past 2 days. Sometimes, while the car is idling, the revs drop by about 100 then rev up to 1,000 on their own. In this split second, the check engine light flashes on then off. The light doesn't even fully light up, it goes away by the time it appears (if that makes sense). The weird thing is, something like this happens while I'm rev matching. Sometimes, when going from 4 to 3, or from 3 to 2, the revs don't "register." All I hear from the exhaust is a little pop. While this is happening, the check engine light flashes in the same manner it did before. The light doesn't stay on for long enough for me to even get a fault code to diagnose the problem. The first time I noticed this, I was also cruising in 4th and the RPM dropped to like 1,000 then back up to 2,000, causing a little "kick." Any thoughts on what it could be?

    EDIT: 4 days ago, my car had a fuel leak at the 2 hoses connecting to the fuel filter. I went to get new hoses for them, but sadly, the shop didn't carry exact hoses for each car, so they had to cut me a new hose which didn't have all the bends the OEM one had so I had to kind of bend them myself. Could the reason this is happening is because not enough fuel is getting to my car at certain points?
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    #2
    I doubt if it would be the hoses. unless you have a distinct kink in one of them. (are you still leaking - this would affect the pressure obviously..

    Check that the arrrows on the fuel filter are correct - is the fuel flowing through the filter in the proper direction? (Im sure they are)

    Next - I would check for vacuum leaks - Vacuum leaks will create a pulse or erratic idle. Hook a vacuum gauge up to the intake plenum (use the nipple right above the valve cover)

    A smoke test will tell you if and where a leak is - however you might not have a smoke machine and or know where to find a smoke machine - so I recommend a vacuum gauge. With a vacuum gauge you can tell that you have leaks - you just cant tell where..

    Vacuum gauge should read steady at idle and read around 17-20 in - depending on your altitude (probably 18-20 in CA)

    Good website for understanding this tool..

    http://www.secondchancegarage.com/public/186.cfm


    next - I would work through fuel pressure - I can send you info from Bentley if needed on how to do this..

    Comment

      #3
      Originally posted by 95BMWIC View Post
      I doubt if it would be the hoses. unless you have a distinct kink in one of them. (are you still leaking - this would affect the pressure obviously..

      Check that the arrrows on the fuel filter are correct - is the fuel flowing through the filter in the proper direction? (Im sure they are)

      Next - I would check for vacuum leaks - Vacuum leaks will create a pulse or erratic idle. Hook a vacuum gauge up to the intake plenum (use the nipple right above the valve cover)

      A smoke test will tell you if and where a leak is - however you might not have a smoke machine and or know where to find a smoke machine - so I recommend a vacuum gauge. With a vacuum gauge you can tell that you have leaks - you just cant tell where..

      Vacuum gauge should read steady at idle and read around 17-20 in - depending on your altitude (probably 18-20 in CA)

      Good website for understanding this tool..

      http://www.secondchancegarage.com/public/186.cfm


      next - I would work through fuel pressure - I can send you info from Bentley if needed on how to do this..
      It's not a vacuum leak. I've had a vacuum leak before and it was nothing like this, plus the check engine light didn't come on before.

      Comment

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