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Whats Fried?!?!

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    #1

    Whats Fried?!?!

    Ok. My grandparents have their 1986 Grand Marquis. It has 39k on it. This summer it developed a rough idle. No biggie I say, just needs a tune up as the parts are all original. It didn't have a check engine light and all the sensors responded to quick testing. So I change cap/rotor, plugs/wires, fuel filter; air filter was already new. All the ignition shit was nasty/fouled. After it's changed it runs a little better but still rough idle. I figure, ok, she hardly gets drove each year and gramps nevAr beats on it so I need to blow out the cobwebs and bad gas. Well, I suck sea-foam through the beast and drive it around and beat on it. Still, a little better but a rough idle. Well by now I'm pissed. I check the timing and before I get around to turning it off to re-connect the spout connector it dies. I'm like, what-ev and go to start it. Nothing. Won't start, no spark. So I get to thinking, hrrmm, TFI modules are notorious for bullshit, and I've had to replace quite a few and always recommend a spare. So I replace TFI module AND coil for good measure as the test light did the blinky thing when I tested it. (I didn't have my multi meter so all I could test for is power). Anyways, after this shit fest it STILL won't start. Now I'm fuming as I feel fairly comfortable around the Ol' 5.0EFI. So I start checking everything, and in the back of the engine there is the wiring harness that goes to the tranny, a 6pin connector I believe. Well that fucker has rubbed through and melted at the back of the engine!!!! Now I know that it has to do with the transmission but could it have wiped out the computer?? It was a white wire that was rubbed through on the intake. Any help or info would be GREATLY appreciated.
    Chris - A 20th Century Man \m/ ^.^ \m/
    Tags: None
    #2
    white wire or white hose? if it was one of those little bastard white vac hoses...
    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

    Comment

      #3
      No, this is wire, I had to cut the damn tape off of it as it was all melted.
      Chris - A 20th Century Man \m/ ^.^ \m/

      Comment

        #4
        there are 2 harnesses back there. one is the oxygen sensor harness, the other is the neutral safety switch / start circuit wiring. I seem to recall the oxy sensor harness goes to a round plug, the NSS one is a rectangular plug. There is a white/pink wire in the NSS harness that us actually the wire that runs from the key switch down to the trans. if that grounded out, about the worst that might happen is the ignition switch might fry, or maybe you'd pop a fuse link upstream and the thing wouldn't crank over. I highly doubt the ECM would be damaged from that.

        You do have fuel pressure and spark right? Whats the wiring around the ECM and fuel pump relays look like? Front corner, next to the wash bottle. Mine were all crusty and it made the fuel pump not run at one point.
        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
          Shit. I also had no idea the transmissions had any electronic anything connected to them except that safety switch. I wish I could help.
          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

          Comment

            #6
            She cranks very nice and I have plenty of fuel, just no spark. I even have power to the coil. And I believe that is the wire Thain. And yeah, the round ones are for 02s. My only theory is that while it's cranking the power is cut off to the ignition circuit. No spark signal..
            Chris - A 20th Century Man \m/ ^.^ \m/

            Comment

              #7
              see if you have power at the red / light blue wire at the TFI connector when its cranking. if nothing, check the red/light blue coming out of the rectangular connector coming up from the trans. Looking at the evtm, it looks like it splits right at that connector. One side goes to the starter relay, the other feeds power to the TFI when cranking. If that wire smoked on the ignition side, that would explain the issue you have.
              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

                #8
                What's fried?


                Chicken.
                And Okra.
                Originally posted by gadget73
                There is nothing more permanent than a temporary fix.
                91 Mercury CP, Lopo 302, AOD, 3.08LSD. 3g upgrade, Moog wagon coils up front, cc819s in the back. KYB GR-2 police shocks. Energy suspension control arm bushings. Smog deleted.
                93 F-150 XLT, 302, ZF 5-spd from 1-ton, 4wd.
                Daily--07 Civic Coupe. Bone stock with 25k miles
                Wife--14 Subaru Outback. 6-speed.
                95 Subaru Legacy Wagon--red--STOLEN 1/6/13

                Comment

                  #9
                  The white wire, would probably be the power wire coming from the ignition switch. It attaches to the Neutral Drive Switch (the indication of the computer to what gear the trans is in, through the NSS. It's tied into the wiring of the neutral safety switch, it would normally be getting 12 volts to it when the key is in the start (crank) position. It would tell the computer if you're in neutral or park, and not that. To raise the idle slightly when the transmission is in gear. Though, if the car still cranks, then that wiring is still working, and didn't short out. Now, if that wire is melted/shorted, the engine wouldn't be able to crank.

                  Have you checked the computer for codes? It might give you some indication to what might be wrong through the KOEO codes

                  Comment

                    #10
                    Replaced the toasted wires and it still won't start. I have power to the module in both the run and start positions. However the ground lead in the TFI harness doesn't ohm properly. There is resistance in it somewhere and I don't know if that's normal or not. Anyfuckinghow I'm starting to feel like a damnned retard. I need to buy a manual and look at the wiring schematic for this boat.
                    Chris - A 20th Century Man \m/ ^.^ \m/

                    Comment

                      #11
                      Originally posted by p71towny View Post
                      Replaced the toasted wires and it still won't start. I have power to the module in both the run and start positions. However the ground lead in the TFI harness doesn't ohm properly. There is resistance in it somewhere and I don't know if that's normal or not. Anyfuckinghow I'm starting to feel like a damnned retard. I need to buy a manual and look at the wiring schematic for this boat.
                      The ground path goes through the tfi module, to the distributor base, to the engine to ground. Try running a jumper wire from the battery ground to the base of the distributor and see if the car starts then.

                      Comment

                        #12
                        Update, its running again. The coil was shot along with the pickup in the distributor. It runs now but still has a miss at idle until it warms up. Has a shit ton more power but I don't know if its nasty gas as it doesn't get drove much or what. Had my buddy use his snap on scanner on it but since its not throwing codes it doesn't show too much. I told my grandpa to drive it and put some fresh gas in it as that shits old. We'll see.
                        Chris - A 20th Century Man \m/ ^.^ \m/

                        Comment

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