MPG Computer for 94 GM ALDL

**Jammer** · 09-16-2006, 06:02 PM

I suppose there are no miles per gallon software for obd1? I found one for eec-vi ford but they want $500.

**84RegalRider** · 09-17-2006, 12:47 AM

nope

**96TransAm** · 09-17-2006, 10:40 PM

I'm not sure how an OBD1 computer could do it, they don't really know how much fuel they are using. Some might be able to do it...but there lies the issue, there was no standard back then so it would need to be made just for that PCM.

**star-art** · 09-18-2006, 02:50 AM

If your car is General Motors, the ECM makes "injector on time" available over the serial data line. If you can somehow tap into this and read it, you can calculate fuel used. I don't know for sure, but I believe that people have hacked into the signals sent over the serial line for GM cars.

The parameter is called "injector on time" and it tells you how long, in milliseconds, the computer is turning on the injectors. Each injector is rated in pounds per hour of fuel used. This gives you the info to calculate the amount of fuel being burned by the engine. It should be very accurate!

**96TransAm** · 09-18-2006, 09:29 AM

Originally Posted by star-art

If your car is General Motors, the ECM makes "injector on time" available over the serial data line. If you can somehow tap into this and read it, you can calculate fuel used. I don't know for sure, but I believe that people have hacked into the signals sent over the serial line for GM cars.

The parameter is called "injector on time" and it tells you how long, in milliseconds, the computer is turning on the injectors. Each injector is rated in pounds per hour of fuel used. This gives you the info to calculate the amount of fuel being burned by the engine. It should be very accurate!

That would require home made software over a ADL cable.

I'll ask around on the fbody boards, if it can be done on a fbody good chance you can do it on other GM cars as well.

**84RegalRider** · 09-18-2006, 03:50 PM

eh i got HomeMade software for ALDL cable.

if you could tell me what byte it is should be no problem.

**star-art** · 09-18-2006, 04:51 PM

Sorry, I have no idea. I just know the ECM reports the data, but I don't have any other specifics as to exactly how. . .

**96TransAm** · 09-18-2006, 04:57 PM

See if your car is supported by TTS Datamaster, load it up and take a look at the injector duty cycles, that might get you started on figuring it out.

**MaZinGeR** · 09-23-2006, 11:10 AM

In base my design foy my camaro ODB1 on this winner project on the circuit cellar website.

http://www.circuitcellar.com/avr2004...05abstract.pdf

You can read the full description on :

http://www.circuitcellar.com/adverti...ghtner-183.pdf

**Mad Jad** · 09-23-2006, 01:16 PM

check out DIY-EFI

As for MPG, why not use a 94 era DIC? I had a 94 grand prix sedan that had a DIC and calculated MPG, range, etc etc. I do not have the DIC anymore, but I'm sure you could find one on ebay or junkyard for ~$20