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91 Merc Grand Marquis won't start or run in park. Will start in neutral but stalls

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    91 Merc Grand Marquis won't start or run in park. Will start in neutral but stalls

    91 Grand Marquis (5.0L with AOD trans) will only start in neutral and stalls if I put in park reverse or 1. It moves in drive but not taking off in lower gear like it should. i have to drive real slow till it gets up to 35 mph then shifts and goes great, almost like there is no 1st gear, it imeediately stalls when shifted into R or P like the engine comes to an immediate break.In 20 years of working on cars I never seen anything like it. Can anyone help please.

    #2
    That's friggin' bizarre.


    I would suspect the neutral safety switch for at least part of your problem.


    In what condition is the transmission fluid? Is it a high mileage transmission that has recently been serviced/flushed, by any chance?


    What is the condition of the TV cable and its bushing at the throttle body? It's the one that isn't the throttle cable or cruise cable. Check at the transmission end, too.



    Can you check it for vacuum leaks?
    sigpic


    - 1990 Ford LTD Crown Victoria P72 - the street boat - 5.0 liter EFI - Ported HO intake/TB, 90 TC shroud/overflow, Aero airbox/zip tube, Cobra camshaft, 19lb injectors, dual exhaust w/ Magnaflows, Cat/Smog & AC delete, 3G alternator, MOOG chassis parts & KYB cop shocks, 215/70r/15s on 95-97 Merc rims

    - 2007 Ford Escape XLT - soccer mom lifted station wagon - 3.0 Duratec, auto, rear converter delete w/ Magnaflow dual exhaust

    - 2008 Mercury Grand Marquis Ultimate Edition - Daily driver - 4.6 2 valve Mod motor, 4R75E, 2.73s. Bone stock

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      #3
      +1 bizarre.

      sounds like the torque converter may be too tight (I thought they would just let go when going bad, not tighten up though) or the engine has severe vacuum leaks or is running f'n rich (re: no low end power).

      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.

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        #4
        I think you have multiple problems. Start with basics. Check codes and vacuum gauge.

        85 4 door 351 Civi Crown Victoria - Summer daily driver, sleeper in the making, and wildly inappropriate autocross machine
        160KMs 600cfm holley, shorty headers, 2.5" catted exhaust, 255/295 tires, cop shocks, cop swaybars, underdrive pulley, 2.73L gears.
        waiting for install: 3.27's, Poly bushings, boxed rear arms, 2500 stall converter, ported e7's, etc

        06 Mazda 3 hatch 2.3L 5AT (winter beater that cost more than my summer car)

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          #5
          Won't start in park? sounds like misadjusted linkage at the trans. as for stalling, dead iac or major vacuum leaks.

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