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    #1

    Odd . . bogging?

    Ok, I suspect I have to change my thermostat, and I have yet to replace the vacuum lines (John, I know, I know . . I tend to procrastinate) . . . but I've run into some odd behavior that I don't think would be caused by either of those.

    Sometimes, if the car's not completely warm and has been only running a short time, I get a sort of rough, bogging-like feeling, which I'd expect from a poorly tuned carburetor. Totally caught me off guard happening in a SEFI vehicle.

    It's slight, but noticeable. My girlfriend in the passenger seat noticed it one evening.
    It ONLY happens under very light throttle.
    It goes away either:
    - after a few seconds, or
    - immediately if I give it more gas (and going back to the same light throttle as before does NOT cause it to return)
    It has only happened 3 times in the past month - and I drive the car almost every day.

    I hate the intermittent sort of problems.....

    Anyway, anything I should look at first? In the past several months, the plugs, wires, cap, rotor, pvc valve, grommet, and screen, air filter, and fuel filter have all been changed.
    1987 Ford LTD Crown Victoria 2-door Coupe - perpetually "sort of" for sale...
    Black with Red cloth (velour?) interior.
    Purchased on 10/10/2008, with only 70,386 original miles, and only ONE previous owner.
    Reader's Ride post, First pic with "new" rims, Other pics with "new" rims
    Tags: None
    #2
    Clean your EGR. Its probably clogged.
    “Cars are the only thing on earth that will beat you, break you, make you bleed, make you cry, spend all your money, spend all your time, not work and not care that you will love more, the more they abuse you.” -Anonymous

    Comment

      #3
      egr acting up or a dead spot in the TPS could cause this. I had problems with my Mark VII when the TPS had died. It gave me a code, which I thought was awfully decent of it.
      86 Lincoln Town Car (Galactica).
      5.0 HO, CompCams XE258,Scorpion 1.72 roller rockers, 3.55 K code rear, tow package, BHPerformance ported E7 heads, Tmoss Explorer intake, 65mm throttle body, Hedman 1 5/8" headers, 2.5" dual exhaust, ASP underdrive pulley

      91 Lincoln Mark VII LSC grandpa spec white and cranberry

      1984 Lincoln Continental TurboDiesel - rolls coal

      Originally posted by phayzer5
      I drive a Lincoln. I can't be bothered to shift like the peasants and rabble rousers

      Comment

        #4
        dead dead TPS will code. TPS with dead spot will not. back probe the TPS signal line (typically green wire) with an analog meter to check for smooth operation. if the needle jumps while you're opening the throttle, change the TPS (make sure you've got good connection first with the meter).

        +1 EGR

        also IAC/throttle body may need cleaning.

        Only two things are infinite, the universe and human stupidity, and I'm not sure about the former. -- Albert Einstein
        rides: 93 Crown Vic LX (The Red Velvet Cake), 2000 Crown Vic base model (Sandy), 2003 Expedition (the vacation beast)

        Originally posted by gadget73
        ... and it should all work like magic and unicorns and stuff.

        Originally posted by dmccaig
        Overhead, some poor bastards are flying in airplanes.

        Comment

          #5
          Will def look into the TPS.

          Would EGR and/or IAC cause that sort of roughness, though, almost like a bumpy/rumbly feeling in the engine? I was almost wondering if I had some kind of odd misfiring thing happening - except that I figure actual misfiring would be a LOT more noticeable.
          1987 Ford LTD Crown Victoria 2-door Coupe - perpetually "sort of" for sale...
          Black with Red cloth (velour?) interior.
          Purchased on 10/10/2008, with only 70,386 original miles, and only ONE previous owner.
          Reader's Ride post, First pic with "new" rims, Other pics with "new" rims

          Comment

            #6
            the TB/IAC being built up with carbon will reduce the idle and if it gets low enough, the car will run, but the idle will not be smooth.

            Only two things are infinite, the universe and human stupidity, and I'm not sure about the former. -- Albert Einstein
            rides: 93 Crown Vic LX (The Red Velvet Cake), 2000 Crown Vic base model (Sandy), 2003 Expedition (the vacation beast)

            Originally posted by gadget73
            ... and it should all work like magic and unicorns and stuff.

            Originally posted by dmccaig
            Overhead, some poor bastards are flying in airplanes.

            Comment

              #7
              It's never happened, thus far, at idle... only under very light/gentle acceleration.
              1987 Ford LTD Crown Victoria 2-door Coupe - perpetually "sort of" for sale...
              Black with Red cloth (velour?) interior.
              Purchased on 10/10/2008, with only 70,386 original miles, and only ONE previous owner.
              Reader's Ride post, First pic with "new" rims, Other pics with "new" rims

              Comment

                #8
                if the idle hasn't gotten low enough to be rough, but is low, it'll do this... a dead spot in the TPS will also do it.

                easy check, engine off, take intake off throttle body. open throttle. If you only see black behind it, clean it out. that's the carbon buildup.

                Only two things are infinite, the universe and human stupidity, and I'm not sure about the former. -- Albert Einstein
                rides: 93 Crown Vic LX (The Red Velvet Cake), 2000 Crown Vic base model (Sandy), 2003 Expedition (the vacation beast)

                Originally posted by gadget73
                ... and it should all work like magic and unicorns and stuff.

                Originally posted by dmccaig
                Overhead, some poor bastards are flying in airplanes.

                Comment

                  #9
                  Will do if time this weekend allows.

                  Clearly I should've kept my mouth shut.. because today, the idle got a little funny.... a bit off, but only a bit.

                  Pulled away from a light, and it did the slightly-rough-at-light-throttle thing. Gave it a bit more gas, which always clears it up, and . . it didn't. Stayed rough. Pushed it a bit harder, no improvement.

                  Let up, still rough. Basically rough no matter what I did, it didn't change.

                  At least, that was the case for about 10 seconds or so. Then it suddenly got butter smooth, and was that way the rest of the way to work.

                  Ah well, I think getting the EGR, IAC, and throttle body cleaned up will be my first course of action.
                  1987 Ford LTD Crown Victoria 2-door Coupe - perpetually "sort of" for sale...
                  Black with Red cloth (velour?) interior.
                  Purchased on 10/10/2008, with only 70,386 original miles, and only ONE previous owner.
                  Reader's Ride post, First pic with "new" rims, Other pics with "new" rims

                  Comment

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