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Ford can’t reprogram my Speedometer. Need solid advice.

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    Ford can’t reprogram my Speedometer. Need solid advice.

    Built myself a ratted up pickup out of a 2007 Police Interceptor and a 66 F250. Changed the tire size and the gear ratio, the speedo is WAY off. Took it to Ford and they said they couldn’t do anything with it because of the tires and gears I picked are not factory options. I was going to put a Dakota digital speedo interface into it to correct it. BUT, I’m not sure if I should tap into the trans output shaft speed sensor, or where. And if I do that, will it mess up the traction control, ABS, or the trans shifting. Any advice on this?
    sigpic

    #2
    Three ways to go about it.
    This is my order of preference, but you're not me and all will work with varying degrees of success:
    1. Ideally, contact a company selling ECM tuners, such as SCT (I like Justin at VMP tuning in Florida) or one of the others--Bully Dog, Sniper, etc. This is pretty easy for them and gives you access to a bunch of other tuning options.
    2. The Dakota Digital setup (or similar pulse converter) can install between the speedometer and the speedo source. I'm not sure on a 2007 whether the ECM sends a signal to the gauge panel with the vehicle speed (are you using the Police Interceptor gauges?). If the ECM sends data to the instrument cluster, you may have to put the converter between the speed sensor and the ECM. That will throw off the ECM calculations a little, but so did putting the wrong size tires on. I'm not sure if the effects are meaningful (how much of a discrepancy is there? I would guess you put much larger tires on?)
    3. Use an aftermarket speedometer and get the speed directly from the output speed sensor. This still leaves the ECM looking at the wrong vehicle speed.

    Any approach that doesn't involve reprogramming the ECM is going to leave it reading off--again, I suspect you put on larger tires, so it will think the vehicle is traveling slower than it actually is. Also, it's riding in a vehicle with different handling characteristics (weight distribution especially) than the CVPI. I don't know how that will affect the ABS and Traction Control, but I think it might affect shift points for economy (engine speed and throttle/accelerator points are more important in transmission gear choice, so you should be okay there).
    I wouldn't worry too much about it, but talking to someone with tuning and engine swap experience (another plug for VMP, and SCT tuners) can probably get you a program that does a lot more than just fixing the speedometer error.
    If you're not driving this in extreme weather or on a track, any of these will be just fine, including option 2a, skip the Dakota Digital price and use a cheap eBay version.

    Comment


      #3
      https://www.autometer.com/gps-speedometers possible easy option

      Hot Rod TV show did a very similar swap I do not remember what they did with the speedometer or harness but it is worth watching you may get some ideas for your conversion that you may not have thought of.

      https://www.hotrod.com/articles/hot-...100-crown-vic/
      Last edited by EaOutlaw1969; 12-28-2019, 06:43 AM.
      2007 Ford Crown Victoria LX Sport

      Comment


        #4
        Seen this done on a Marauder. Not sure what the specific tuner used was, but basically you just set the rear gear ratio and tire size and it fixed the speedo. NBD.

        The trans shift scheduling relies on proper speedo input too, so you really want to fix it in the computer.
        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
          A tune would be the simplest fix and SCT is the ideal one to use because more people have experience with them. Not sure if Blue Oval Chips is still in business but that's who the CVN guys swear by for tuning these cars. I'm sure pretty much anybody that tunes and sells tuners would be ok though. I understand Bama performance is also great to deal with.

          Comment


            #6
            Talk to Marty.
            https://www.mosspeedshop.com/

            Comment


              #7
              I swapped in 4.56 gears, and have a 245/65R17 tire on it. I’m using the Dakota product on a different vehicle, and it worked great on that but I don’t have ABS or any of that. I’m just wondering if I where to tap into the signal on this vehicle to change the speedo reading, without messing up the abs/traction control/trans shifting. I’m using the police guages. Basically just did a sheet metal swap. It’s got the car dash and all that in it still. I know that there’s a speed signal wire at the ECM, and I’m guessing the ECM sends the signal to the cluster, because that’s the color of the wire that everything says is the vehicle speed wire. The wires at the sensor on the trans are totally different colors. So, basically getting the signal changed right at the cluster would work the best?
              sigpic

              Comment


                #8
                Or is that going to still make the computer hit the speed limiter early because the computer will still think it’s going faster than it is? It’s about 20 mph off at 80. So it reads 80 and I’m actually going about 60.
                sigpic

                Comment


                  #9
                  +1 a proper tune from a non-ford source (Marty, SCT, HP-tuners, etc) will fix that. I'd say go the do-it-yourself route with an SCT unit if you just want to change gear/tire settings and not much else over the canned tune. Quick an easy. If you need to delete EVAP/EGR/rear O2s, you'll have to get something specialized from HP tuners as they are the only ones left that can actually tweak emissions related stuff for 07+. At least until the federal lawsuits finish. Feds killed SCT in that regard about a 6 years ago.

                  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


                    #10
                    Did some math to find the ratio of the new tire size to stock tire size and the gear setting to use in the PCM is 4.10 if you don't tweak the tire size setting.

                    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
                      Well, I could use a rear O2, EGR, EVAP delete as well, main concern was the speedo at the moment. But a custom tune might be down the road because I have full length headers and free flowing 3 inch exhaust too, and plans for Cams later down the road. BUT 4.10s isn’t a option in the computer, but that’s talking factory stuff that I have access to at this moment. I was basically hoping to wire in the interface/converter I already have on hand to make the speedo right so I can just drive. Lol.
                      Last edited by hav24wheel; 12-28-2019, 01:59 PM.
                      sigpic

                      Comment


                        #12
                        Click image for larger version

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                        Here’s the two wires in question. The Green/yellow comes from the trans output shaft speed sensor, and the Gray/black is the one going into the cab that should be the vehicle speed signal wire. Just not sure the consequences of changing the signal to the computer vs from the computer.


                        Sorry about the multiple posts, I’m kinda all over the place on things right now. Lol
                        Last edited by hav24wheel; 12-28-2019, 02:22 PM.
                        sigpic

                        Comment


                          #13
                          I would definitely not do that. You'll probably get some strange error code if the engine rpm and selected gear don't jive with what the PCM sees on the trans output shaft speed sensor.
                          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


                            #14
                            Ya, I’m not sure! I was hoping to find out here, because on my 99 E350 van I did a 4x4 conversation on, I had to change the signal coming from the trans to the computer, because the type of sensor between the 4x4 pickups and the Vans have a different location for the speed sensor. The pickups where in the rear axle and the vans in the tailhousing of the trans and the 4x4 trans didn’t have that, so used the output shaft signal to make the speedo work, and that works without codes/shifting issues. So, that’s why I thought it would work on this too BUT the van doesn’t have traction control or functional ABS.
                            sigpic

                            Comment


                              #15
                              Its also older, which might matter.

                              I remember Seneeb did a gear swap in a 97 and changed the gear on the VSS to correct the speedo. He said it had shifting problems and the speed limiter kicked in at like 70 because it was rpm based. The speedo read correctly but the ECM wasn't using that signal to control things. He tuned it for the different gearing and it quit being stupid.
                              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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