Reading ODBI - Fuel Economy, Hypermiling, EcoModding News and Forum

Hellmark · 04-11-2009, 01:50 PM

I have a '89 Grand Am with a 2.5L, and I'm looking at making some instrumentation for it. Primarily because the stock gauge cluster isn't exactly accurate (No tach, speedometer reads slow the faster you go, temp gauge is wildly off, and gas gauge is never accurate except when the tank is full). Playing around with my OBDI scanner, I get accurate readings, but I don't want to have that hooked up all the time since it is bulky. Now, I know I could buy new gauges, but I am a maker, and am wanting to start poking around with this sort of thing.

Now, looking around, I have not come up with much info for OBDI projects. Tons of stuff for OBDII, though. The only info that I've gleaned is that it appears to be RS232 based. Any of you guys messed with getting info from the computer on OBDI cars?

cfg83 · 04-11-2009, 02:03 PM

Hellmark -

Welcome to EM! I don't have an OBDI car so I haven't done anything with that.

If you're a maker then you sound like a candidate for the MPGuino :

OpenGauge / MPGuino FE computer - Fuel Economy, Hypermiling, EcoModding News and Forum - EcoModder.com

I Googled "OBDI protocol" and found this :

The History of Onboard Diagnostics OBD1, OBD 1.5 & OBD11-Virtual Mechanix

Quote:

In 1985 OBD-1 was introduced to standardise the way in which vehicle systems could be monitored. The list of functions OBD1 would have to achieve grew with the need for real time misfire detection, Lambda sensors, the catalytic converter and fault code capability.

CarloSW2

cfg83 · 04-11-2009, 02:29 PM

Hellmark -

Here's some more interesting reading :

AVR Freaks :: View topic - Looking for OBD-I link specs for '92 Olds Eighty Eight...

CarloSW2

Hellmark · 04-11-2009, 03:28 PM

cfg, thanks.

I actually came here because of the mpguino. I want to build one, but also want to have a few other functions. Like I said, most of my gauges are kinda crap, so, get good replacements. I have an open spot on my dash from the factory (right above where it bends down and merges with the center console), and want to put a 7 segment array and a 16x2 LCD display there for tach on the 7 segments, and then temp and a few other things from the OBDI on the 16x2. Then I was thinking mpguino up higher on the dash. If I really get crazy, I was pondering the idea of just gutting my gauge cluster, and messing with those (either mounting there, or controlling those).