After Install Questions

[wclement7]

Finally found some time to install my mpguino and it works! YAY

Some questions I may or may not be missing the in wiki...
I understand it needs to be calibrated, but should the speed be off my 50+ mph the first use?

My gauge shows zero mph and mpg until i get over 15mph, is this normal? Or do i need to use a smaller resistor on the vss?

This needs to be always powered or it loses settings etc, is there a way to have the backlight turn off after a certain amount of time with no vss or injector signal?

Thanks for the help everyone!

[dcb]

Not sure about the vss, got a schematic or better yet a scope?

The backlight should timeout and the current trip reset after 7 minutes of no vss signal and no injector signal (user configurable).

[wclement7]

I used the schematic found here:
combustory.com/wiki/index.php/MPGuino ( i can't get it to load right now...)

I do not have a way to get a scope of the signal unless there is an easy way to display that on my computer? I do have a spare arduino, maybe a simple sketch would work?

Thanks for the quick reply!

[dcb]

I mean a schematic for your car, i.e. a link to a schematic maybe. Not sure what it uses for VSS, or what you have tapped into, or what it's signal looks like.

[wclement7]

Oh I'm sorry I misunderstood.

I went to this page:
rostra.com/main/vss-search.php
Searched for my vehicle and used the information it gave for the vss. I grabbed the signal off the back of my speedometer, grey/black wire.

I do not have anything else schematic wise that I have been able to find online. I tapped into one of the injectors directly, the one that has 0volt when key is on but not running.

Is that what you needed?

[emilix123]

The VSS count is fairly straight forward. There is a device on your car that rotates and creates a certain number of pulses per revolution. The sensor is usually attached to your transmission and it has a direct gear ratio to your tires that I will call the rolling ratio. This sensor is used to feed the vehicle computer the speed and distance data. The actual gear ratio has only one main variation, and that is the tire diameter. For the MPGuino to calculate the the MPG, this input is critical for determining the distance traveled. The VSS count is typically measured in counts per mile.