MPGuino + OBDguino

[snydertalon]

So, I started to not comprehend what was going on after the first 9 pages of the OBDguino thread, and decided I would ask my questions outright.

Is it possible to make an MPG/OBD hybrid? I still want all the extra information from the OBD, but I plan on making an HHO cell, which throws off the MPG data if polled from OBD. The injector pulse is the only way, for HHO, to accurately read the actual MPG. Otherwise the formula used (like scanguage) inaccurately measures the mileage.

Beyond saying that I read it from a bunch of people, I cannot back that up. Just like you are all much smarter than I with the vss and OBDII codes/standards, the other people who I get my HHO mpg data from are far smarter than I am regarding that.

Does the obd read multiple o2 sensors?

Also I was wanting to do 20x4 to get more data. How difficult is this? And do I just need to recode the open source to get it to display?

Cliff notes
Want a hybrid
Want a bigger lcd
What multiple o2 sensors displayed

[dcb]

You read my mind, sort of

I am experimenting with a "simplified" iso interface since I can't find the freescale chip in the usual haunts. Anyway, the test bed is a duino and a piece of protoboard with a couple resistors/transistors all hotglued to the back of a 4x20. After I hack some of the obduino screens to display all the pids I want on the 4x20, I was going to just throw it on the dash next to the mpguino and have two displays

Havent got it working yet, but with the guino handling distance and fuel, I'll have a whole 4x20 with access to all the pids to display anything else, w/source code control.

It is "possible" to make a hybrid, but it is a complete rewrite and probably a larger microcontroller.

Bigger LCD is quite possible, but needs custom programming, don't complain if it doesn't work. Bigger LCD + another LCD = even better

multiple 02 sensors is probably vehicle dependant, research the obd details of your vehicle.

[snydertalon]

I was reading the obduino.pde at

obduino.pde - opengauge - Google Code

Line 125 and 135 have input of oxygen sensors 1 and 2 respectively

What is the data being polled? If its the narrowband voltage off the sensors, would a formula make somewhere shortly after 945 more accurate?

The coding assumes a constant 14.7:1 ratio, but some vehicles have a variance of 12->25 (during coast/hard accel/other than perfect conditions). If we were able to manually enter our low and high, or even a few 10ths of a volt each way, the formula would become ridiculously more accurate (variable vs. constant).

But that is based off 125 and 135 getting the voltage from the 02 sensors.


It is also 1AM for me, and I will use that as an excuse for all my fallacies I have presented (if found)

[snydertalon]

is there a listing of parts to go buy for the OBDguino?

So far I've got (not bought but think I need to)

Arduino Duemilanove
Arduino Duemilanove

OBD to Serial Cable
J1962M to DB9F, Type D Cable - ScanTool.net
(unless someone knows a place to get the pars to make 1)

An HD47780 compliant LCD
SparkFun Electronics - Basic 16x2 Character LCD - Amber on Black 3.3V

An MC33290 Chip
MC33290 Product Summary Page

But, to me, it seems like I am missing something or a lot of somethings

Thanks for the help

[dcb]

You havent mentioned your year/make/model. You might want to make a garage entry and track your fuel so we can all see if the instrumentation helps.

Oh, and welcome to ecomodders

[snydertalon]

Originally Posted by dcb

You havent mentioned your year/make/model. You might want to make a garage entry and track your fuel so we can all see if the instrumentation helps.

Oh, and welcome to ecomodders

04 Honda Accord. I am to lazy to make a garage entry. I have on at gassavers.org (don't ban me, I don't know if there's some internet fight going on)
Gaslog data for Accord

I have two big reasons for wanting one. Doing things like pulse glide efficiently, I havn't figured it out and might need to accelerate more slowly, but I won't know, or if aero mods are even worth it.

The other I need to make a MPGuino not OBD for, so I'll just run them both as you mentioned. I need a pulse width mpg calculation because of a calculation error that happens when you run off OBD.

Thanks

[snydertalon]

Is there a way to add sensors to either of the two? I want to either check a temperature of something I add to the system and/or check its current draw

How difficult is it to recode both/either system to output 8 items on 2 lines? (40x2 lcd)?

[dcb]

You can hack in some sensors to the mpguino or the obduino, they both have a couple analog pins to spare and can be hacked to have even more, but you will have to maintain your hacks.

The display code isn't difficult. gotoxy, lcdprint, etc. might need to tweak a couple hard coded values to get it to work right on a larger display. It will probably work with a 4x20 or a 2x40 by default (if the controllers are compatable) but just wont take up the whole screen.

[snydertalon]

I guess I will hack it into the MPG since OBD has a crap ton of information to begin with