Announcement

Collapse
No announcement yet.

Erratic Speedometer

Collapse
X
Collapse
 
  • Page of 1
  • Filter
  • Time
  • Show
Clear All
new posts
Previous template Next
    #1

    Erratic Speedometer

    So I’m cruising in to work at 55 MPH when I looked down and bam… the speedometer started bouncing back and forth between 65 and 70. This has happened before, usually at higher speeds (like 70-80), but would settle back down after a while. This time it did not.

    So what do you think? Cluster going bad?


    sigpic

    I'd rather be a failure at something I love than a success at something I hate.
    George Burns
    Tags: None
    #2
    I wonder if a bad vehicle speed sensor would cause this.

    Comment

      #3
      Don't think my car has that. It's mechanical. The speedometer cable plugs from the transmission into the back of the cluster. Sorry, I forgot to say it's a 1986 Grand Marquis.


      sigpic

      I'd rather be a failure at something I love than a success at something I hate.
      George Burns

      Comment

        #4
        The most common reason for this is a dry cable inside it's housing. Pull the cable housing from the back of the cluster and pull the cable out. Lubricate the cable with a graphite-based lubricant or lithium grease. Note: The cable cannot be pulled out from the transmission end.

        Comment

          #5
          +1 lube the cable or if it's frayed, replace it. Check to make sure it's also not burned through from resting on the exhaust.

          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

            #6
            I have good luck with lubricating the cable with Dexron or Type F tranny fluid. WagonMan
            89 Colony Park
            90 Colony Park
            70 HEMI Daytona Convertible

            Comment

              #7
              Took apart the cluster (dash already apart) and lubed all the moving parts with lithium grease. Even tighten the loose mileage reset arm. Went for a quick drive. Smooth smooth. Even feels like the correct MPH now. Before it felt like it aways read high. The end of the cable was not frayed and had lubed it up the last time I had the cluster out. Will get a better idea on my way to work tonight.


              sigpic

              I'd rather be a failure at something I love than a success at something I hate.
              George Burns

              Comment

                #8
                An 86 does have a VSS. But the only thing that uses it (to my knowledge) is the cruise control.

                I'm still running the VSS from my '84 in my '90. It's been in there for 8 years, and has well over 200K on it.
                1990 MGM: $50 E7 heads, HO cam, Holley SysteMAX lower intake, HO upper intake with an Explorer TB. LSC ECM. Lincoln logs into stock dual exhaust. K&N drop in air filter. Wide ratio AOD, 2400 converter with a 3.08 one tire fire out back. Car is less slow now. Then there's the '92 Beater. Dual 2.25" exhaust with shiny tips. Rumbles nice. Super slow. Burns oil too.

                Comment

                  #9
                  yep, its for cruise only in 86. 88+ it feeds into the ECM mostly for cruise, but EGR functions are also somehow keyed from it. No VSS lets the EGR open too soon and you get a funny hesitation off-idle. Took me years to find and fix that problem on my car.
                  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
                    the 93 Mustang engine in the Mark had that off-idle BS... when I finally hooked up a VSS to the ECM... that BS went away. drives much nicer now.

                    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

                      #11
                      basically the same thing here. Fixed it after I went mass air. I hooked it up to make the VSS code go away, and it fixed that too. I had been asking for a long time if VSS input had anything to do with EGR function and I never got a "yes" answer. Until I found out that it did of course, then a dozen people chime in with "well of course it does you moron". I still don't pretend to fully get how 87- EGR works since there is no VSS input on those. I guess it just uses engine RPM and load or something to determine when to open the valve.
                      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

                        #12
                        I think the lube fixed my problem. Nice and smooth on the way to work tonight. I don’t have to worry about the cruise or the EGR. They are both inop. The cruise control box under the dash shorted out. So it's unplugged and is why the dash was mostly apart already. EGR is by choice.


                        sigpic

                        I'd rather be a failure at something I love than a success at something I hate.
                        George Burns

                        Comment

                          #13
                          EGR is good for a little bit of fuel economy if its working properly. I'm a cheap bastard, so I'll take the tiny bit it buys me.
                          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

                          Previous template Next
                          Working...
                          X