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    #1

    Voltage/ Idle drop when put in gear

    My 92 has done this since I bought it but its much more noticeable with the heater and or lights on. I cant tell if its idle speed drop causing the voltage drop or the other way around.
    At idle in park its 14.5-14.8v Mostly 14.8. As soon as its put in gear the idle drops, lights dim, heater slows, etc. Voltage drops to 12.5v instantly.
    Is there something other than charging system I should be checking?

    edit: No codes set either.
    Tags: None
    #2
    have the alternator tested, might be on it's way out

    1986 lincoln towncar signature series. 5.0 HO with thumper performance ported e7 heads, 1.7 roller rockers, warm air intake, 65mm throttle body, 1/2" intake spacer, ported intakes, 3.73 rear with trac lock, 98-02 front brake conversion, 92-97 rear disc conversion, 1" rear swaybar, 1 3/16" front swaybar, 16" wheels and tires, loud ass stereo system, badass cb, best time to date 15.94 at 87 mph. lots of mods in the works 221.8 rwhp 278 rwt
    2006 Lincoln Town Car Signature. Stock for now
    1989 Ford F-250 4x4 much much more to come, sefi converted so far.
    1986 Toyota pickup with LSC wheels and 225/60/16 tires.
    2008 Hyundai Elantra future Revcon toad
    1987 TriBurner and 1986 Alaska stokers keeping me warm. (and some pesky oil heat)

    please be patient, rebuilding an empire!

    Comment

      #3
      Originally posted by Lincolnmania View Post
      have the alternator tested, might be on it's way out
      You mean not putting out enough amperage at idle?
      Even when it drops the volts are still 12.5. It should be enough to run it fine, unless amperage is an issue.
      I was also wondering about the IAC. Is there a way to test it or just replace it?

      Comment

        #4
        12.5 is the battery alone. it should be at least 13V at any time if the alternator is working right. Check that the charge cable is tight as well as the rest of the connections. If that doesn't help, get it tested. There's lots of stuff that can fail internally, though it's usually just the regulator that can be replaced pretty easily on the back of it.

        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
          Had the alternator tested yesterday and it was putting out almost 15v and 110 amps. Tested as good.
          It only drops when put into gear along with the idle speed dropping to a near stall. So far it never actually stalls.
          It will run with no battery in it aswell although it stalled once putting it in gear while tha batt was out and heater was on high.

          Comment

            #6
            in that case, you probably just need to clean the throttle body (carb/throttle body cleaner works great - follow the directions on the can). Since you have the old aluminum intake, there's no worries about the cleaner eating the intake. You probably just have excessive carbon buildup in there. You may also need to clean out the idle air control motor passages. Sounds like the alternator is doing the low rpm drop on you.

            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
              One thing i was wondering is if the alternator is just weak at lower rpms and when they tested it they were spinning it fast enough not to see it. Otherwise it runs good and a very smooth idle in park. Smooth in gear if i keep the rpm up just a bit, basically to where it should be.

              Comment

                #8
                that's what I'm thinking... and you probably just have a low idle issue... hence my troubleshooting the low idle issue.

                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

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