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    #1

    Vacuum Issue or Emissions Issues?

    My mom's CV seems to have this super low idle. I sort of fixed it with a replacement IAC, but it has been slowly coming back. I gotta stick the CV int he driveway and check for codes and such; but I figured I would get some opinions beforehand. Nowadays, when at a stop, with the brakes applied, it almost stalls out. If I put the car in nuetral and let it idle, it's okay. Once I hit the brake (even in nuetral), the idle slows dramatically and the car wants to stall out. Anybody got some ideas on what that is? Perhaps the 26 year old brake booster is going? Thanks in advance for any help



    Packman
    Tags: None
    #2
    how is the vacuum line going to the booster?......could also be the check valve at the booster also.....if it is even related to that......check for a vacuum leak....everywhere....(vacuum lines....intake manifold etc.....)

    Comment

      #3
      I changed most of the vacuum lines a couple years ago when replacing the valve cover gaskets and upper intake gasket ( I had everything apart at the time). The master cylinder was replaced several years ago. The booster is untouched. Without having the time to sit and look at the car, I am just guessing; giving the symptoms. I think it's vacuum related though. I will go over the vacuum lines again and see if something died along the way. I also couldn't change the PCV screen at the time because it was jammed in the intake so tight, that even using tapping screws and vice grips didn't work. Perhaps I should start thinking about the starting fluid diagnostic to see if the lower intake manifold gasket is still good. Also, I couldn't find the adapter fitting for the MAP sensor, so I duct taped the line to the MAP sensor. The line that was on the engine leading from the underside of the upper intake was tapered. The line had a smaller input (at the intake) than the output (at the MAP sensor). I know that comes loose and I have to replace the tape every once in a while. I gotta look for that fitting, if they're available locally.


      Packman

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        #4
        does the booster hold vacuum? Mine had a bad grommet that caused it to leak. Could still be a bad IAC. The aftermarket ones are questionable. You'll get codes if its shot, I forget which but it either gives a cannot control idle high or cannot control idle too low, depending which way it failed.

        use a plastic vacuum hose reducer to get to a smaller fitting. Use a short piece of line that fits the MAP, connect that to one end of the reducer, and use the fat end to connect to the manifold side line.
        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

          #5
          Thanks Gadget73! I will go to the auto parts store next weekend and see if one of them has a reducer like that.

          I took the throttle body off of the intake manifold and thoroughly cleaned it out with gum cutter. I took the replacement IAC (Standard) and replaced it with the stock unit that I completely cleaned out a month ago. I put it all back together and it ran a little faster than normal at idle. It seemed to stay cooler longer too as I still saw steam coming out of the tailpipe after 10 minutes of idling. I drove the car around town and it idled smoothly. My mom ran errands with it all day and it was running smoothly. At the end of the day I went to put gas in it and on the way back it started getting that choppy low idle again at a stop light. When I got home I parked the car and left it running in gear with my foot on the brake and it remained smooth. So I have concluded that I have fixed a symptom of a larger problem.

          I couldn't find my Actron scanner, so I was unable to scan the CV. I will continue to look for it. I did notice however, that the new IAC had a bit of oil inside of it. It has only been on the engine for a month. The throttle body had a puddle of oil at the bottom of the throttle blade. I am wondering if the crank case breather ( the tube that runs from the oil filler neck to the throttle body) is spitting oil into the intake. Do you think it's spitting a vapor of some sort that's hindering the airflow or idle characteristics?



          Packman

          Comment

            #6
            check for a bad pcv valve.....crank case breather...and gasket issues

            Comment

              #7
              Yeah, I am contemplating a trip to the JY and getting a lower intake from one of the 5.0L engines. I will change the pcv screen with the intake off of the engine and then install it. That's the only part of the pcv system that I haven't changed yet. At this point, I should probably just change the engine.

              Comment

                #8
                lower intake doesn't really have anything to fail, but make sure the PCV valve and it's related crap is in good shape. I've had problems with mine popping out of the grommet before because the aftermarket grommets don't sit in there too snugly. I fixed it by putting some heat shrink tubing around the PCV valve itself to make it fatter, and that held everything together.
                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

                  #9
                  It could be a possibility that is happening. Though, everything looked intact when I checked. If anything, I suspect the screen would be the weak point now, since I couldn't change it out four years ago. I don't know how old the current screen is; assuming that it has been changed before.


                  Packman

                  Comment

                    #10
                    if you tried and failed to get it out 4 years ago, its probably original. Most people don't know its even back there. They also usually only get really jammed if its all clogged up.
                    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

                      #11
                      packman: Which grade of gas are you running in the car?
                      '79 Continental Town Car
                      '90 Crown Victoria LTD
                      '94 Crown Victoria

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