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WTF? 91 5.0 misfire still?????

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    #1

    WTF? 91 5.0 misfire still?????

    I have a 91 merc with an anoying misfire when the car gets warm...its high mileage and not sure what this could be...seems to change with engine temp and the weather....anyone got any ideas?

    car had a complete tune up in october past and the module on the distribute replaced last weekend.(module was a huge improvement but still has a bit of a mis at times)
    Last edited by Sign of the Cat; 04-13-2007, 10:47 PM.
    Tags: None
    #2
    How long has it been since the ignition system was overhauled?

    2001 Ford Crown Victoria P71 - "The Fire Engine"
    1985 Lincoln Town Car Signature Series
    But God demonstrates his own love for us in this: While we were still sinners, Christ died for us. Romans 5:8

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      #3
      Coil and associated wiring? Also check the big connectors on the intake that are for the engine harness.... Those cause all kinds of issues.

      Maybe you have my old car. i got fed up with it and traded it in... Poor milage and a mysterious miss...
      Builder/Owner of Badass Panther Wagons

      Busy maintaining a fleet of Fords

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        #4
        which ones are they cause i pulled a huge mouse nest out of under the plenum. bought this car from a friend who never had any problems till he parked it for a few months....was thinking about the coil myself too

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          #5
          the mouses might have chewed into some wiring.....this is common

          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!

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            #6
            Originally posted by lincolnmania View Post
            the mouses might have chewed into some wiring.....this is common

            Bingo! A buddy of mine's Mustang had a mouse nest underneath the intake, and it ate some of the injector wiring. It also then started with a funky miss............... Then it melted a valve on Nitrous.

            Found the eaten wiring AFTERWARDS.................
            1989 Town Car Cartier: 3G Alt. Upgrade, Mark VIII Electric Fan, Police Interceptor Suspension, 40-series Flows, loaded. HO+ Conversion: E7 heads, Cobra 1.7RR's, Explorer intake, 65mm TB, FMS "E" Camshaft, 4-hole 19lb/hr injectors, A9P ECM, 76mm C&L MAF, BBK CAI. 338,000Km, stock bottom-end.

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              #7
              Probably won't help, but have you pulled the codes by any chance?
              1990 Country Squire - under restoration
              1988 Crown Vic LTD Wagon - daily beater

              GMN Box Panther History
              Box Panther Horsepower and Torque Ratings
              Box Panther Production Numbers

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                #8
                Originally posted by lincolnmania View Post
                the mouses might have chewed into some wiring.....this is common
                mouses?
                Nick
                88 Colony Park LS
                G-pa's old car, but he's cruisin around heaven in his 69 wagon now
                Future plans:Semi HO conversion, or Explorer motor swap, shift kit, PI springs and sway bars, KYB-GR2 shocks

                Comment

                  #9
                  Could be a bad injector if the wiring is ok.
                  You could use your timing light and go form cylinder to cylinder to see if it is spark related. If that is OK, then you could pull 1 plug wire at a time until you see wich cylinder is missing.

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                    #10
                    problem is intermitting.....???? ran like a dream today but yesterday was a bag of shit
                    also seems to act worst between 50 and 70 kms/hr

                    Comment

                      #11
                      I wonder if maybe the temperature sensor isn't going funny. If the coolant temp sensor is bad, it messes up the fuel mix calculations and the EGR operation. Just a thought. Codes might tell you something useful, or you might need to meter it out to verify its in range. The chart matching temperature to resistance can be found here:

                      http://fordfuelinjection.com/index.php?p=28
                      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

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                        #12
                        The BIG connectors... The biggest ones on the car...Back of the intake Behind the EGR spacer.
                        Builder/Owner of Badass Panther Wagons

                        Busy maintaining a fleet of Fords

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