Aftermarket MPG gauge VSS question

[n_grimm]

Hello all. I have installed an MpGuino mpg gauge, similar to a Scangauge II on my 88 BII. It gives me instant MPG, tank MPG speed, distance traveled etc but has one problem. If I go below around 10 mph the speed and instant mpg drop to zero so it isn't logging mpg or distance until I speed up. I have it connected to the vehicle speed sensor (VSS) at the ECM which from what I've read here comes from the ABS on the rear diff. The MpGuino folks said that if it is just a magnetic sensor, they don't work at very low speeds. INot a problem for the ECM to control cruise control or converter lock up. I'm guessing the newer rigs with the electronic speedo use a different sensor. Anyone know if there would also be VSS on the transfer case and if so what type it would be? Thank you.

 

[ronclark]

I been looking at getting MpGuino, how are you liking it so far and is it worth it?

 

[n_grimm]

I have the assembled unit for $55. shipped and it got here in less than a week. Being diy it doesn't have a case but Radio Shack has some that can be modified. I like it a lot especially since there aren't a lot of options. The hookup is easy and they give you four pin connector to make your own cable and it plugs into the MpGuino's connector. I used the wire from of an old usb cable. The menus are a little hard to understand at first and the only manual is on line but there is a forum section at ecomodder that is used to support it. They pointed me to a how to on adding a hall effect sensor to the driveshaft if the Bronco II doesn't have one. It is more than usuable now but I've got an idea on how to condition the existing VSS signal to at least lower the speed at which it quits counting the speed pulses.

 

[n_grimm]

Not having much luck using the sensor from the diff or the transfer case tail shaft since they are both just magnetic sensor and don't deliver a high enough voltage at lower speeds. Someone mentioned on another forum that maybe my truck would have a sensor on the speedo itself. My Bronco II has a mechanical speedo and odometer so didn't know how likely it is to have either an optical or hall sensor. It's kind of a job getting the speedo so I was hoping someone here knows. Thank you.

 

[ronclark]

if you get all up and running right let us know.
I know there is a write up in the tech lib about using a ford MPG computer, thy used to put in the higher end cars.
it sounds like a simpler option, if you can find the box.

 

[n_grimm]

I got it to work using a few components from Radio Shack. The mph starts to register as soon as the Bronco begins to move. I am able to use the vss signal that goes to the ECM like before but I am converting it's sinewave to a squarewave (digital signal) that the Mpg gauge likes better. The hookup isn't that much harder either.