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DigiDash Tripminder Fuel Mileage Calculator.14LB vs 19lb injector. 87 Town Car

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    DigiDash Tripminder Fuel Mileage Calculator.14LB vs 19lb injector. 87 Town Car

    I read somewhere that the tripminder in the digital dash Lincolns make it's fuel mileage calculations based on 14Lb injectors and that if you do the H.O. swap and use 19Lb injectors, your calculations will be off. I wanted to see if anyone can shed some light on this. I find it hard to believe that's how it works. I would think that it would have to make calculations based on fuel flow at the rail vs mileage. I don't see how the injector size could impact the reading. There is no sensor at the injector. Where is the fuel flow calculated? My tripminder seems accurate and consistent. I usually show about 14mpg city and about 21mpg on the highway and an average of 16-18 dependant on how I drive it which is about what I would expect this combination of parts/vehicle weight would do. I have never compared the mechanical odometer with the tripminder but I can tell you that I do have the correct speedo gear for 3:55 and a T5 and it is accurate to within 1 mph at 65mph according to my gps so I am not concerned with that being a variable.
    87' Lincoln Town Car Stars + Stripes. Explorer GT40P, Anderson B31 Cam, Shorty Headers, FRPP 1.6 Rockers, A9L, Sn95 T5 Trans, 3:55 Limited Slip, GNX Rear Springs, LSC Turbines, 1.5 wheelspacers, Full Custom Dual 2.5/Flowmasters, 00 P71 Airtube, 19lb calibrated Maf, Summit Alum Radiator, King Cobra Clutch, Short throw Shfter, Energy Susp Trans Mount,
    Mods to come: Big Brake/Poly Front Swap, PI Front Swaybar, Addco 650 Rear Swaybar, Boxed Upper Rear Control Arms, 351/Alum Heads, FRPP Valve Covers,

    #2
    The ECM is where the injector size data is stored. The digital dash just gets fuel flow data from the ECM based on injector on-time. If you use a 19# injector on a computer that expects a 14#, the mileage will be off and it will run stupidly as well. The "calibrated" MAF that lets you use different sized injectors without re-programming the ECM will skew the fuel flow data in the same way.
    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


      #3
      Speed desity system calculates fuel use from the speed desity map and speedo gearing / tire size / rear gear combo.
      Mass Air is based off the Mass air chart and tire size etc just like the Speed Density set up. As gadget mentioned a off set MAF witll screw up the readings and will also screw up performance. If the proper ECM is used with all the matching parts ie injectors and such the Trip minder should still be accurate.
      Scars are tatoos of the fearless

      Comment


        #4
        Gadget I understand ECU/Injector/Maf sizing has to match. I have a A9L/19Lb/Calibrated 19lb MAF. My question is still whether or not the Tripminder is impacted by this change.

        Originally posted by gadget73 View Post
        The ECM is where the injector size data is stored. The digital dash just gets fuel flow data from the ECM based on injector on-time. If you use a 19# injector on a computer that expects a 14#, the mileage will be off and it will run stupidly as well. The "calibrated" MAF that lets you use different sized injectors without re-programming the ECM will skew the fuel flow data in the same way.
        87' Lincoln Town Car Stars + Stripes. Explorer GT40P, Anderson B31 Cam, Shorty Headers, FRPP 1.6 Rockers, A9L, Sn95 T5 Trans, 3:55 Limited Slip, GNX Rear Springs, LSC Turbines, 1.5 wheelspacers, Full Custom Dual 2.5/Flowmasters, 00 P71 Airtube, 19lb calibrated Maf, Summit Alum Radiator, King Cobra Clutch, Short throw Shfter, Energy Susp Trans Mount,
        Mods to come: Big Brake/Poly Front Swap, PI Front Swaybar, Addco 650 Rear Swaybar, Boxed Upper Rear Control Arms, 351/Alum Heads, FRPP Valve Covers,

        Comment


          #5
          Are you guys suggesting that the Tripminder references the ECM for it's calculations? Are you suggesting that if I change to the A9L it will or wont throw off the Tripminder? I'm still unclear about the above posts.
          87' Lincoln Town Car Stars + Stripes. Explorer GT40P, Anderson B31 Cam, Shorty Headers, FRPP 1.6 Rockers, A9L, Sn95 T5 Trans, 3:55 Limited Slip, GNX Rear Springs, LSC Turbines, 1.5 wheelspacers, Full Custom Dual 2.5/Flowmasters, 00 P71 Airtube, 19lb calibrated Maf, Summit Alum Radiator, King Cobra Clutch, Short throw Shfter, Energy Susp Trans Mount,
          Mods to come: Big Brake/Poly Front Swap, PI Front Swaybar, Addco 650 Rear Swaybar, Boxed Upper Rear Control Arms, 351/Alum Heads, FRPP Valve Covers,

          Comment


            #6
            the tripminder has 2 inputs. One is from the VSS for vehicle speed. The other is from the ECM for fuel flow data. The ECM feeds the fuel flow data to the tripminder. The tripminder has no clue or concern about what size injector is in there. The only thing that cares is the ECM. You could put 100 lb injectors in there, program the ECM to know it has 100 lb injectors, and the tripminder would remain accurate.
            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


              #7
              Excellent. Thank you. That means that my tripminder is working accurately like I suspected. BTW Gadget, where did you ever learn this stuff?

              Originally posted by gadget73 View Post
              the tripminder has 2 inputs. One is from the VSS for vehicle speed. The other is from the ECM for fuel flow data. The ECM feeds the fuel flow data to the tripminder. The tripminder has no clue or concern about what size injector is in there. The only thing that cares is the ECM. You could put 100 lb injectors in there, program the ECM to know it has 100 lb injectors, and the tripminder would remain accurate.
              87' Lincoln Town Car Stars + Stripes. Explorer GT40P, Anderson B31 Cam, Shorty Headers, FRPP 1.6 Rockers, A9L, Sn95 T5 Trans, 3:55 Limited Slip, GNX Rear Springs, LSC Turbines, 1.5 wheelspacers, Full Custom Dual 2.5/Flowmasters, 00 P71 Airtube, 19lb calibrated Maf, Summit Alum Radiator, King Cobra Clutch, Short throw Shfter, Energy Susp Trans Mount,
              Mods to come: Big Brake/Poly Front Swap, PI Front Swaybar, Addco 650 Rear Swaybar, Boxed Upper Rear Control Arms, 351/Alum Heads, FRPP Valve Covers,

              Comment


                #8
                The ECM dosent actually measure the fuel but bases it off calculations of data programed into the computer and some external inputs. One for a carb set up actually measures the fuel flow. I have gallon per hour ones on my boat.
                Scars are tatoos of the fearless

                Comment


                  #9
                  On second thought how could the tripminder use VSS as an input when my 87 Town Car didn't come equipped with one from the factory? It has one now since I installed it with the MAF swap, but the tripminder couldn't have been using it prior.
                  Originally posted by gadget73 View Post
                  the tripminder has 2 inputs. One is from the VSS for vehicle speed. The other is from the ECM for fuel flow data. The ECM feeds the fuel flow data to the tripminder. The tripminder has no clue or concern about what size injector is in there. The only thing that cares is the ECM. You could put 100 lb injectors in there, program the ECM to know it has 100 lb injectors, and the tripminder would remain accurate.
                  87' Lincoln Town Car Stars + Stripes. Explorer GT40P, Anderson B31 Cam, Shorty Headers, FRPP 1.6 Rockers, A9L, Sn95 T5 Trans, 3:55 Limited Slip, GNX Rear Springs, LSC Turbines, 1.5 wheelspacers, Full Custom Dual 2.5/Flowmasters, 00 P71 Airtube, 19lb calibrated Maf, Summit Alum Radiator, King Cobra Clutch, Short throw Shfter, Energy Susp Trans Mount,
                  Mods to come: Big Brake/Poly Front Swap, PI Front Swaybar, Addco 650 Rear Swaybar, Boxed Upper Rear Control Arms, 351/Alum Heads, FRPP Valve Covers,

                  Comment


                    #10
                    On a digital dash Lincoln, it uses the one inside the cluster. It uses the same one for the cruise control. Ford/Mercury have a standard VSS in the trans for cruise control, and tripminder if needed. Starting in 88, the ECM required VSS input as well, though I'm not entirely certain if Lincoln had a VSS in the trans for everything starting in 88 or if it kept using the one inside the cluster. The non-digital Towncars had a VSS at the trans for the cruise control.


                    true, its not directly measured, its based on injector duty cycle and programmed flow rates and such. You could have a massive fuel leak from a stuck injector, and the ECM can't tell you about that. If you had the wrong injectors in there, you'd have no way for the tripminder to know that either. The carb stuff has a device that measures actual fuel flow.

                    and I read a lot. You'd be amazed the crap you can piece together by reading the various tech manuals. I also tend to remember a lot of goofy details. Someday, someone will craft a Trivial Pursuit game that I will absolutely pwn at.
                    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


                      #11
                      Hey Gadget. Here's one for you. I frequently hear a vibration seemingly coming from behind my guage cluster. What could this be? I believe it is increasing with speed of the vehicle. Must be something mechanical spinning in there huhh? Now here's another one... I noticed today while climbing a hill with cruise control on, the car was set at 40MPH, but the digi odometer was bouncing from 40,34,35,38, and back to 40. I've never seen the speedo bounce like that before. I can't say whether It does it while not in cruise, but this is the only time i've seen it do it thus far. It normally will skip but only increase or decrease. Never seen it bounce up and down. Any idea?
                      Originally posted by gadget73 View Post
                      On a digital dash Lincoln, it uses the one inside the cluster. It uses the same one for the cruise control. Ford/Mercury have a standard VSS in the trans for cruise control, and tripminder if needed. Starting in 88, the ECM required VSS input as well, though I'm not entirely certain if Lincoln had a VSS in the trans for everything starting in 88 or if it kept using the one inside the cluster. The non-digital Towncars had a VSS at the trans for the cruise control.


                      true, its not directly measured, its based on injector duty cycle and programmed flow rates and such. You could have a massive fuel leak from a stuck injector, and the ECM can't tell you about that. If you had the wrong injectors in there, you'd have no way for the tripminder to know that either. The carb stuff has a device that measures actual fuel flow.

                      and I read a lot. You'd be amazed the crap you can piece together by reading the various tech manuals. I also tend to remember a lot of goofy details. Someday, someone will craft a Trivial Pursuit game that I will absolutely pwn at.
                      87' Lincoln Town Car Stars + Stripes. Explorer GT40P, Anderson B31 Cam, Shorty Headers, FRPP 1.6 Rockers, A9L, Sn95 T5 Trans, 3:55 Limited Slip, GNX Rear Springs, LSC Turbines, 1.5 wheelspacers, Full Custom Dual 2.5/Flowmasters, 00 P71 Airtube, 19lb calibrated Maf, Summit Alum Radiator, King Cobra Clutch, Short throw Shfter, Energy Susp Trans Mount,
                      Mods to come: Big Brake/Poly Front Swap, PI Front Swaybar, Addco 650 Rear Swaybar, Boxed Upper Rear Control Arms, 351/Alum Heads, FRPP Valve Covers,

                      Comment


                        #12
                        in the 89 and older cars, the speedometer is cable driven. If the cable is in need of replacement, this could be it. It could also be the speedometer/odometer as well. Lincolns also used a VSS mounted in-line on the cable for the cruise if it was an analog dash. Not sure if/when they changed over to the trans mounted VSS for cruise.

                        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


                          #13
                          yeah, sounds like your speedo cable needs lube and/or replacement. I think the 80s Towncar may be the only cable driven digital dashboard ever created. The Mark VII was electronic, even the analog dash models.


                          The trans mounted thing was present by 86 at least with analog gauges. I would guess it was as far back as 84 at least. Before that, i am not knowing.
                          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

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