MPGuino

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I saw MPGuino fuel economy meter on ecomodder.com forums, and i decided to make those myself too.

http://ecomodder.com/forum/opengauge-mpguino-fe-computer.html

What it does?

MPGuino can display you an instant, trip or total fuel consumption info.

Where it can be installed?

It can be installed in any car that has electronic injection system. Almost any car from the -90s to present.

All it needs is a signal from speed sensor and a signal from any injector. And of course 12V operating voltage.

Does not work with carburated systems.

How does it work?

MPGuino monitors speed and how long the injectors are open. From that, it can calculate the fuel consumption.

Anything else?

After installation, all you have to do is calibrate it. So you take a paper and a pen, write how much you tanked at fuel station, and after some time of driving when you need to tank, you do little bit of math and input the results into MPGuino. Then it displays correct readings.


Features

It can be installed in any car that has electronic injection system. Almost any car from the -90s to present. Check your car before purchasing!

All it needs is a signal from speed sensor and a signal from any injector.

Doesnt work with carburated systems.

Fuel consumption as instant, current trip and whole tank

Time-To-Empty-screens

Supports metric(L/100km), U.S.(MPG) and Imperial(MPG) units

Support for Chrysler returnless fuel injector correction factor, based off of intake manifold pressure. Utilizes existing manifold pressure (MAP) sensor built into the existing engine control system, but requires an additional barometric sensor (in other words, a spare/extra MAP sensor).

screw-terminals for inputs

pushbuttons installed facing up.

Integrated USB-programmer(USBasp), so no need for additional programmers. All you need is an mini-USB cable

additional pins for customization

Current consumption: running(highest brightness) below 70mA, sleep mode below 30mA

Board is made for t vagos code from ecomodder.com


Calibrating MPGuino

The information below is written when version 1.1 was new. 1.2 has way more features.

First you might want to adjust speed/consumption/inj delay near the right values.

If ”Instant”, is zeros all the time, then you need to adjust ”Inj Delay mS”, it might be way too much, (meaning how fast the injector opens). Default is 500mS. Then you adjust it for example 50mS at a time up until you can see the instant consumption. It is not so critical what is shows, as long as something. After that, you can fine-adjust it more.

So basically, you want to adjust speed roughly, and estimated consumption, and then balance both values so it displays somewhat right. After that, it is ready to be calibrated:

  • Reset the trip meter. Add fuel.
  • First drive like 100km or something. More accurate it becomes that more you drive. I recommend that you drive the whole tank from full to almost empty.
  • Compare MPGuino trip to car trip, calculate the percentual difference, and edit ”VSS Pulses”. As an formula:
  • VSS Pulses * MPGuinoTrip / CarTrip = New VSS
  • Compare MPGuino litres(or gallons) used (On Tank-page. Dont be confused with average or Current reading!), to how much you added fuel. As a formula:
  • Inj Pulses * MPGuinoLitres / FilledLitres = New Inj Pulse

Simple as that. But do it in same order that i told! Speed needs to be calibrated first, then consumption. Consumption is straight related to speed.

Installing MPGuino in general

I recommend to use four-wire cable if available. It looks cleaner.

Wire size can be about anything. 0,25mm² or smaller is good. There is no big currents.

Inj:

-Turn the key until power is on. Power, not engine, meaning you turn the key until you can see lights on panels etc.

-Find the injector connector. On multipoint-injection systems, one injector signal is enough.

-Disconnect the connector, and use a multi-meter.

-Measure what of the wires is 12V. Dont use that wire! Use some other. You are lucky if there is only two wires, then it is the another.

Or alternatively, you can open the carburator unit and look what is the signal. Usually the ECU controls the injectors with ground(minus), so you look for + and . Or you can find a datasheet for your car systems and look for there.

VSS:

Vehicle Speed Signal. Usually you can find a connector attached to gearbox. Myself, i found the correct connector by disconnecting one at a time until the speedometer stopped working. (You need to know what you are doing)

In some cars, it is in radio connectors. Usually made for that car radio can adjust the volume by speed.

If your car has only mechanical speed-sensor, you can add an reed-relay or hall-sensor in the speedometer to get electrical pulses.

+12V and GND:

12V needs to be constant. Meaning straight from battery without any relays or switches/keys on its way.

GND meaning ground, minus. The chassis.