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1986 Mercury Grand Marquis dies when idling.. please help!!!

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    1986 Mercury Grand Marquis dies when idling.. please help!!!

    First off, I’m glad I stumbled across this site. I didn’t know that the Grand Marquis had any fans! Seems like I was wrong!

    Anyways, I just recently purchased a dark blue 1986 Mercury Grand Marquis LS (which I'll get some pictures of up soon) for $500 from a neighbor of a friend a few months ago. The odometer just rolled over 300 miles ago, and the exterior is in fairly good condition, though there a few places were the paint has chipped slightly and a few minor dents.

    So far I’ve replaced a line for the power steering (it had a pretty bad leak), replaced the radiator with a brand new one (which was extremely hard to track down, but easy enough to actually install), installed a brand new water pump, had the engine heating block replaced by a mechanic, replaced the heating hose and several other hoses, inflated the tires, and cleaned up the spark plugs, which is amazing for me because I don’t know much about cars.

    However, here’s my problem -

    The car is running horribly when idling. It’ll rev up, then die down, then rev up and die down again… it’ll do this for a few minutes, and then finally the engine will die and the car will shut off. When this happens, the engine light comes on, and so does the battery light. If I try to turn the car on though immediately after this, it'll start up, but the same sputtering thing will eventually happen, and it'll die if I don't get it moving. It’s fine when I’m driving it, but if I’m stuck at a stop light for more than two minutes or so it’ll die. If the lights headlights are on and it’s sputtering like this at a stoplight the lights will flicker and continuously fade in and out as well. When I start her up the engine sounds very rough as well.

    This started happening about three days ago, after I got back from a 200 mile trip with it. It’s usually just been driven for short trips before that. Other things that I’ve noticed since I got back is that there is more exhaust than usual coming out when I start her up and it smells worse then usual. There is a also strange rattling noise coming somewhere from the driver’s side of the engine while driving. I’ve checked under the hood and I can’t spot any obvious problem, and there are no puddles forming on the ground from any leaks I can see.

    The sound that my engine is making when idling sounds almost exactly like the car in this video that Zoomie posted a few days ago -

    http://video.yahoo.com/watch/5058961/13441518

    I’d really appreciate any advice anyone could give me. I’m not so savvy with automotive lingo, but I’ll give you guys any more information about my car if it’ll help! Thank you so much!
    1986 Mercury Grand Marquis 5.0 LS, named "Ulysses "


    #2
    Sounds like an IAC (Idle Air Control) problem.

    The lights flickering is just because these cars have pathetic alternators, so when the engine is turning over slowly enough to nearly die, the lights don't get enough juice to light up, since engine RPM=alternator RPM.

    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)

    Comment


      #3
      I would replace those spark plugs. Cleaning them usually doesn't do much. I'd also be looking at the condition of the cap and rotor, the plug wires, and the fuel filter. Any or all of those can make for a bad idle. The surging is quite probably a vacuum leak, but bad tune up parts will have an effect on this too.
      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

      Everything looks like voodoo if you don't understand how it works

      Comment


        #4
        Check the IAC for the idling problem. It's located adjacent to the EGR valve on the EFI engines. In the video you posted, the camera man pointed right at it for a little bit; it was the rusty solenoid right behind the yellow dipstick. Unplug it and it's held in by two small bolts that are a little difficult to get at. Once you pull the IAC valve off, shoot some carb cleaner into the opening until it's oil-free. You'll probably need another gasket which you can't buy alone so you (or at least I did) have two options. You can buy gasket paper and cut one out yourself or you can go to an auto parts store and get a Fel-Pro intake gasket kit and it'll have the IAC gasket included. This was the same exact problem I had with my '86 CV and this solved my idling problems.



        Packman

        Comment


          #5
          Thanks for the quick replies everyone! I'll check out the IAC for problems this weekend, and I'll tell you what happens. Hopefully I can figure it out!
          1986 Mercury Grand Marquis 5.0 LS, named "Ulysses "

          Comment


            #6
            i always start out with a complete tune up if the tune up parts are of unknown age, and check/replace bad vacuum lines, get a vacuum and fuel pressure reading, then i check for stored trouble codes in the ecm......mostlikely your idle air control valve is gooped up or not working

            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


              #7
              take off IAC clean thoourghly with brake cleaner and reinstall make sure you have another gasket mine was somewhat usable still so i coated it with copper srpay seal and has worked scince then
              89 townie, mild exhuast up grades, soon to have loud ass stereo....

              Comment


                #8
                Alright, it’s been a busy week, so it has been hard to actually get some time under the hood. But today I was looking around and discovered three broken lines. The first one is a small, hard plastic tube with a light blue stripe on it that is approximately where I circled in blue on this photo I assume this is a vacuum line of some sort?



                (This picture is NOT of my Grand Marquis, but it is very similar. These are from LTDMan’s ‘87 Ford Crown Victoria. I’ll get actual pictures of my engine up when I track down my digital camera.)


                The second line is located approximately here, circled in red. It is a thick rubbery tube, and is partially melted where it broke near a little plastic connector. It goes in under this big metal thing that says EFI 5.0 (I’m pretty new to working on cars and I don’t know what ever part is! What is this unit?) I can feel the other part of the line under this metal unit, but I can’t quite reach it enough to connect it back to the other section of the line, so I assume somehow I’ll have to take this big metal unit off… which looks difficult. The other end of this line connects to this little computerish looking box approximately where I outlined in white. ( I don’t really see it visible in the engine of the car in the photo)

                The third line that is broke is circled in green, and is of the same type as the last one and broken in the same way. It goes under the big metal unit, but in the front…

                I’m guessing these are all vacuum lines? Could they be causing the problem?

                The stalling has gotten worse, by the way. Now my Grand Marquis will stall out right before I get to a stoplight, when I’m slowing down as it gets close to 0mph. The only way to prevent this is to rev the engine and give the car some juice. It still turns on alright, but I have to get it moving very quickly or it will die.

                Any ideas on how to fix these three lines? The small one with the light blue line looks easy enough, but it’s the bigger two that go under the big metal unit with the EFI 5.0 on it that are worrying me… I don’t think I can get to them without removing that unit… how would one go about this?

                Also, I’ve outlined in yellow where I think the IAC valve is… am I correct? I’m going to clean this part out as well when I get the chance… I’m sure it’s pretty full of gunk!



                I'm getting a new set of spark plugs this weekend as well, hopefully I can get 'em all in. =]

                Thanks for the continued help!
                Last edited by WilliamFredrickson; 06-11-2009, 02:54 PM.
                1986 Mercury Grand Marquis 5.0 LS, named "Ulysses "

                Comment


                  #9
                  Yellow is the IAC, yes.

                  Small blue line is probably for the climate control. Can't think of anything else thats blue. Yes, its vacuum.

                  Pretty much any rubber hose at that area is a vacuum line. It goes from the upper intake (the thing with the 5.0 plate) to a plastic tree on the firewall. There are also several other hoses that go off the upper intake to various places. Back there somewhere is the PCV valve, which should be stuffed into a hole in the lower intake, right in back where its hard to see. The factory PCV valve is plastic, and it does have a largish vacuum line to it which tends to get rubbery from oil exposure. If thats unhooked or broken, thats a major vacuum leak and could be the whole problem.
                  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

                  Everything looks like voodoo if you don't understand how it works

                  Comment


                    #10
                    Alright! I took off the upper intake today, and was able to get at the ruined vaccum lines that went into it. I successfully replaced them, and cleaned out the IAC control valve with carb spray... took me about 3 hours to get everything out of the way enough for me to do it, but...

                    Problem solved! My Grand Marquis runs great now! No more stalling when idle!

                    Thanks for all of the help!
                    1986 Mercury Grand Marquis 5.0 LS, named "Ulysses "

                    Comment


                      #11
                      pretty big feat for someone who couldn't even name the upper intake two days ago.. Nice work mang.

                      as far as the rattle is it constant or only sometimes?? it could be the heatshield on the cat converters, or the converter broke up into chunks on the inside..
                      Give a man a fish and he will be fed for a day. Teach a man to fish and he will promptly forget that he once did not know, and proceed to call anyone who asks, a n00b and flame them on the boards for being stupid.

                      Comment


                        #12
                        Thanks, cld783!

                        The rattle seems to happen only when the car is moving... It comes from the driver's side of the engine as far as I know... I peeked about everywhere yesterday, but I can't seem to spot anything that looks loose. Where is the heatshield on the cat converters located?
                        1986 Mercury Grand Marquis 5.0 LS, named "Ulysses "

                        Comment


                          #13
                          Damn!!!! Just three hours!?!? It took me a whole weekend to do all of that and change the valve covers and gaskets. Kudos to you mang!!!!



                          Packman

                          Comment


                            #14
                            Originally posted by WilliamFredrickson View Post
                            Thanks, cld783!

                            The rattle seems to happen only when the car is moving... It comes from the driver's side of the engine as far as I know... I peeked about everywhere yesterday, but I can't seem to spot anything that looks loose. Where is the heatshield on the cat converters located?


                            its the outter shell of the converters, if you can bend them up or down at all just keep bending until it pops off. it's also possible the converter broke up into pieces and chunks are stuck inside..
                            Give a man a fish and he will be fed for a day. Teach a man to fish and he will promptly forget that he once did not know, and proceed to call anyone who asks, a n00b and flame them on the boards for being stupid.

                            Comment


                              #15
                              Big hose clamp around the converter also works. I ripped mine off tho, only one corner was held 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

                              Everything looks like voodoo if you don't understand how it works

                              Comment

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