OBD MPGuino gauge

[KJSatz]

My car is a 2008 Honda Civic LX. The wiki said that all 2008 model year and newer cars are supposed to use CAN, so I use CAN right? Is there any way you know of to look up for sure if I have a MAF sensor?

I would need a 'duino, that ELM interface thing I see on the wiki, an LCD, and the OBDII --> whatever that serial connector is, right? I live near a Radioshack; which items would be better to buy there (if any), and what is the recommended website to buy the other components for the ELM interface? I think I'll just buy a pre-assembled arduino clone. I know a lot of this information is probably elsewhere in the thread/wiki, but I guess I am kind of looking for a "straight answer." Now I'm excited to do this!!!

[Magister]

I am almost certain Civics have a MAP and not a MAF, it should work but will need a little tweaking of a value. Your car should talk CAN yes.

You can buy the OBD-II to serial cable here
OBD Diagnostics, Inc. - OBD2 Cable
Radio-Shack will not have it, it's hard to find in store, it's better to buy it online.

If you have a serial port on your PC/laptop, you can buy a assembled maxserial for less than $20 at Fundamental Logic webstore.

For all the others components, I know digikey in the USA is a good online supplier.

For the ELM interface, note that C5 and C6 are monolithic, the others are standard ceramic. For C3 and C4, the value depends on the crystal, it's written on it and in the description on digikey webstore for instance.

EDIT: you can buy the ELM327 only on their web site:
http://www.elmelectronics.com/

[KJSatz]

My desktop has a serial port, so that's a great option for the arduino clone! It's out of stock for now, but hopefully it will be back in soon.

Would I want to PDIP or SOIC ELM327?

One other question about the ELM327...an ebay search of ELM327 gives a long list of like PC to OBDII adapters that use ELM327 for less than $10. Do you think there's any way to harvest an ELM327 from one of those, or would it be impossible to get out intact and usable? Edit: Never mind, looks like all of them have like $25 shipping so it wouldn't even save money....

Finally, I have no idea what this means...I am an electronics novice. "For the ELM interface, note that C5 and C6 are monolithic, the others are standard ceramic."

Thanks so much for all the help. Hope I'm not polluting the thread too much .

[Magister]

Originally Posted by KJSatz

Would I want to PDIP or SOIC ELM327?

You want a PDIP, the SOIC is very small and hard to solder.

Originally Posted by KJSatz

One other question about the ELM327...an ebay search of ELM327 gives a long list of like PC to OBDII adapters that use ELM327 for less than $10.

They use fake clone of an old version, maybe the 1.0, of the chip. All these chinese clone are badly done and some does not work because of bad soldering and all. They certainly use an SOIC anyway. Do not touch them. And shipping is $$$ as you noticed.

Originally Posted by KJSatz

Finally, I have no idea what this means...I am an electronics novice. "For the ELM interface, note that C5 and C6 are monolithic, the others are standard ceramic."

About the diagram of the interface on the wiki page. If you order on digikey you'll have to know this. I will try to do a better list of components

[Magister]

FYI, I tested it on a 2008 Pontiac G5, it works like a charm. No need to tweak anything, it displayed fuel consumption, various temperature, load, etc.

I noticed that it uses more fuel than my 07 Elantra, for instance at idle with engine coolant at a good temperature, my Elantra takes 0.7L/h and the G5 takes more than 1.0L/h

Also it seems the G5 does not have DFCO.

[KJSatz]

I'm sorry to be such a lame bother like this, but could someone point me to a complete list of parts for a CAN OBDuino and where a good place to buy them is (US)? Thank you so much.

[ac7ss]

Is there going to be a Wiki page for this? It would be a good idea.

[Magister]

There is a wiki page here
opengauge - Google Code
I'll work on the part list, but except the combo "duino, lcd, transistor/resistor for brightnesss, 3 buttons", you only need the ELM327 and what's written on the diagram (for CAN)

[Magister]

Here's a part list for the interface, you also need a small prototyping PCB (digikey PC5-ND I think, not sure), soldering iron, etc

DigiKey reference:

BASIC:
1x ELM327 (only at ELM Electronics)
3M5480-ND 1x support DIP 28
300-8469-ND 1x crystal 4.000MHZ
490-3697-ND 2x 18pF (see exact load capacitance with crystal)

FOR VOLTAGE:
P4923-ND 1x 0.1 µF monolithic 16V
10KQBK-ND 1x 10 Kohms
47KQBK-ND 1x 47 Kohms

FOR CAN:
MCP2551-I/P-ND 1x MCP2551
3M5473-ND 1x support DIP 8
4.7KQBK-ND 1x 4.7 Kohms
100QBK-ND 2x 100 ohms
BC1022CT-ND 2x 560 pF
P4923-ND 1x 0.1 µF monolithic 16V

FOR ISO:
22KQBK-ND 1x 22 Kohms
47KQBK-ND 1x 47 kohms
2.2KQBK-ND 2x 2.2 Kohms
510H-ND 2x 510 ohms 1/2 Watt
2N3904FS-ND 2x 2N3904 NPN

[dcb]

I like that schematic

couple notes:
You might want to bump up c1 to about 330uf or more to help prevent brownouts while cranking. Or draw it in context with the existing power supply.

Lose the rs232 circuit all together and voltage monitor, there is probably a pid for system voltage, no?


I definitely like the color coding