Fuelly Forums - OBDII CarPC MPG Calculator

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Fourthbean -

I did a "repair return" on mine because I couldn't get it to work reliably. I am guessing that they won't find anything wrong with it. Depending on how things work out, I may try to use a PDA for datalogging. My wife has old Palm Pilots and a newer color m130 I could use for this (she's not using it).

CarloSW2

Hopefully they can get you fixed up, I know that I have run mine for a couple 40 minute runs with no problem. I hope nothing comes up like what you are dealing with.

PDA sounds nice, much easier than a laptop. I had a very small 3lb laptop that I was using in the passenger seat but I really couldn't look a it safely while driving. A PDA up high on the dashboard ought to be much better.

I currently have my screen installed where my radio was. And a full size desktop computer sitting in the floorboard of the back seat. I am awaiting the inverter I bought on ebay so that I can run it for more than the 15 minutes a 175 watt inverter can handle.

Fourthbean -

Quote:

Originally Posted by Fourthbean (Post 78487)

Hopefully they can get you fixed up, I know that I have run mine for a couple 40 minute runs with no problem. I hope nothing comes up like what you are dealing with.

...

They were great. They couldn't find any problem, but they replaced it anyway. Very classy. I think I figured out what was wrong. My PC has too many apps running. As a result, they are probably fighting for the COM1 port. Here is what I did :

1 - I bided my time and found an obsolete 2.5" 4GB hard disk for $10. This way, if I crash the disk proving the system, I don't care because the hard disk is worthless anyway.

2 - I installed a base XP OS on the 4GB hard disk in my laptop. That way, there is no contention for the COM1 port.

3 - I downloaded the "scantool v1.13" software that comes with it. Since it comes with source code, I could customize it after ...

4 - ... I downloaded the "allegro" game programming library for Windows/XP :

https://alleg.sourceforge.net/wip.html (download all422.zip)

5 - I used my trusty Visual C++ version 6.0 to compile Allego. I procastinated doing this because I expected it to be a PITA. It in fact was easier than I thought. This is the power of gamer-programmers. They are edge and MAKE IT WORK! Pssst: But, you don't need to compile it. There are also pre-compiled binaries at the URL in Step 4. Stooopeed me did it the hard way.

6 - Once I had the library, I made a Visual C++ 6.0 project for the scantool software and customized it for my SW2 :

Still working on the color pallete, :o :
Attachment 1253

These are the only variables that are available for my Saturn :
Attachment 1254

4 - But the really big thing is that I got it to log data. I am logging in 1 second increments. I post-processed this to be one minute increments in this example result :

Code:

YYYMMDD,HHMMSS,Absolute Throttle Position (%):,Engine RPM:,Vehicle Speed (MPH):,Calculated Load Value (%):,Timing Advance (Cyl. #1) (?):,Intake Manifold Pressure (inHg):,Short Term Fuel Trim (Bank 1) (%):,Long Term Fuel Trim (Bank 1) (%):,Intake Air Temperature (? F):,Coolant Temperature (? F):,O2 Sensor 1/Bank 1 (V):,O2 Sensor 2/Bank 1 (V):

20080407,201137,13.367,2021.100,52.533,46.817,35.150,17.542,1.088,-7.000,71.900,170.133,0.518,0.721,

20080407,201242,8.130,1952.400,54.867,30.302,37.975,11.647,-0.082,-7.367,74.783,186.950,0.537,0.621,

20080407,201348,13.787,1964.333,55.350,48.922,36.117,19.197,0.623,-7.000,80.067,190.000,0.590,0.710,

20080407,201455,11.310,1886.717,53.233,39.983,39.208,15.507,1.322,-5.495,87.533,190.000,0.481,0.732,

20080407,201601,16.863,1900.667,53.817,53.895,27.317,21.542,-1.065,-2.300,95.667,190.000,0.389,0.638,

20080407,201709,13.510,1953.183,55.133,45.238,37.333,17.980,-0.237,-2.300,103.133,190.000,0.471,0.669,

20080407,201814,8.403,1908.133,53.733,29.813,41.208,12.020,-1.097,-3.200,105.000,190.000,0.354,0.671,

20080407,201919,8.272,1777.917,50.000,31.502,35.792,12.173,-0.502,-4.167,105.000,190.000,0.346,0.718,

20080407,202023,10.620,1863.317,52.800,38.110,39.350,14.567,0.650,-2.300,105.000,190.000,0.283,0.574,

20080407,202128,7.085,1562.167,52.383,35.080,30.592,14.065,2.123,-5.700,106.533,190.500,0.517,0.616,

20080407,202234,11.227,1724.267,49.000,42.093,32.433,15.575,0.395,-5.617,105.367,190.133,0.452,0.541,

20080407,202339,8.697,1782.100,50.017,36.640,35.825,14.210,1.973,-2.640,107.000,190.000,0.461,0.551,

20080407,202446,9.245,1394.267,44.483,41.762,25.108,16.237,0.217,-6.210,106.833,191.033,0.502,0.572,

20080407,202549,10.242,1607.800,50.583,41.063,30.183,16.167,2.068,-5.530,105.567,190.500,0.352,0.396,

20080407,202653,7.198,1347.733,42.583,33.838,23.225,13.590,0.687,-7.867,106.267,191.833,0.483,0.436,

20080407,202758,8.723,1548.133,43.383,39.198,30.417,15.017,-0.398,-5.953,109.467,190.133,0.606,0.500,

20080407,202901,10.207,1615.150,45.067,38.272,30.058,15.563,0.347,-3.800,111.000,190.000,0.407,0.405,

20080407,203003,10.637,1653.900,46.233,41.332,33.733,15.853,-0.970,-2.300,111.200,190.000,0.565,0.496,

20080407,203104,8.885,1590.700,44.533,38.265,33.633,15.340,0.365,-2.300,112.000,190.767,0.559,0.539,

20080407,203207,12.003,1580.317,48.100,42.422,23.208,16.358,0.420,-5.190,113.600,191.600,0.429,0.404,

20080407,203307,13.262,1574.500,48.517,44.165,23.692,17.822,0.033,-5.460,114.333,191.500,0.488,0.551,

20080407,203409,11.132,1537.083,48.250,42.305,24.108,17.785,1.690,-4.510,112.967,190.800,0.431,0.626,

20080407,203515,17.900,1854.267,52.183,55.985,24.950,23.225,-1.523,-2.300,112.800,192.000,0.459,0.630,

20080407,203622,16.592,1829.983,54.367,49.727,25.608,21.535,-0.722,-4.170,112.000,192.000,0.464,0.731,

20080407,203724,7.418,1364.150,41.400,34.622,22.500,15.088,1.102,-5.190,111.017,191.550,0.321,0.272,

20080407,203829,13.582,1543.383,46.683,46.947,21.217,19.203,-2.012,-6.230,111.533,192.083,0.474,0.498,

20080407,203934,8.992,1511.517,48.533,38.937,23.875,16.125,1.495,-7.893,111.733,192.000,0.522,0.300,

20080407,204037,6.512,1385.333,44.033,31.723,26.550,12.637,2.392,-6.220,110.500,190.667,0.499,0.524,

20080407,204148,4.633,1420.150,48.117,26.790,26.808,11.128,2.470,-8.820,108.467,190.867,0.561,0.520,

20080407,204253,5.087,1332.000,43.350,29.773,25.800,11.532,2.833,-9.665,105.033,190.333,0.484,0.562,

I used this to make a *simple* RPM vs MPH chart that shows my engine on coasting :

Attachment 1255

My long term goals are :

1 - Testing only. At this point, I want to see the behavior of mods like my EFIE, the IAT resistor mod, and maybe some aero mods.

2 - Get a solid state hard disk. I can get a 2GB hard disk for $60 right now. If I run the 4GB until it crashes, the price will be lower by then.

CarloSW2

That's great, you got much further than I did. I was trying to do everything from Linux and could barely get the serial port open and a program reading the info from it :(. I wimped out and bought a scangauge 2.

If you are looking for a cheap solid state drive you can look at compact flash to ide adapters for laptops. I had my old p3 set up with a 2GB compact flash card before it was stolen.

Fourthbean -

Quote:

Originally Posted by Fourthbean (Post 95617)

Yeah, Linux is better, but I just went with "what I knew".

I have a CF card, but I don't think my circa 2003 BIOS can boot to the flash-card and/or the card isn't "smart enough" to mimic an IDE drive. I may return to the flash card route (I have a savvy friend who can help me). Well see.

It was plain luck that I got it to work. I expected all sorts of allegro nightmares, but it was almost slam dunk. The scantool source code is well written.

I just realized that *if* I could define an MPG algorithm for all the data inputs, I could create an ##.# MPG LCD in my rear window. That is something that other GasSavers have wanted to have in the past.

CarloSW2

CF was designed to the IDE protocol, there's a lot of older hardware using them with the adapters, which are basically just connection adapters, not interfaces.

RoadWarrior -

Quote:

Originally Posted by RoadWarrior (Post 95628)

CF was designed to the IDE protocol, there's a lot of older hardware using them with the adapters, which are basically just connection adapters, not interfaces.

Ok, then maybe I'll give it another whack. I do have a connection adapter lying around.

CarloSW2

No PID01 10 available?

I don't have PID01 10 available and i would like to calculate the MPG or any form of that gas consumption on my Saturn 2000 SL? Can i obtain that using different values out of my car?

Lucas

Re: OBDII CarPC MPG Calculator

Quote:

Originally Posted by skewbe (Post 77394)

Yes logging would be good.

Look for the following PIDS coming out of your computer:
$PID07 (fuel trim)
$PID0D (Vehicle Speed)
$PID10 (MAF)

if you don't have PID10 (MAF) then look to see if you have:
$PID07 (fuel trim)
$PID0D (Vehicle Speed)
$PID0B (Manifold Pressure)
$PID0F (intake air temp)
$PID0C (RPM)

if I do not have MAF, how can I calculate the fuel consumption from these values?

Re: OBDII CarPC MPG Calculator

Wow, you guys are way more advanced at this than I. I'm trying to find something that will calculate mpg from an OBD1 port, I'm guessing there isn't enough data from an OBD1, but am not familiar enough with the process to know.

I'm doing some aerodynamic changes to my RV and it would really help to have an mpg calculator on board for short term testing.

By the way Carlos, the Saturn aero mods are working out great, I never answered your last question which was, do the clear headlight covers diminish the light coming from the headlights. Saturn stock headlights aren't exactly flame throwers and I don't notice them being any worse so I'd have to say no. The grille block off plate made a big difference and so far, zero overheating. Hottest weather so far has been 102 degrees with the A/C on in traffic, no problem.

I'm looking at the cost effectiveness of various molding procedures, if I can do it reasonably I may offer an aero kit for the 97 to 2000 SC2's. Blocking off the grille, covering the headlights, and taking off the side mirrors resulted in an 18% increase in mileage. After several weeks of tweaking map settings, O2 feedback settings, and installing an A/F gauge to monitor the results, and getting zero net gains because the computer kept jumping all over my attempts to 'tune' it, this is good stuff. Bolt it on and forget it. I like it.

Next up is a full belly pan and a modified windshield wiper base. I'm building a truncated (partial) boat tail for my RV. If that tests out with good results I may try that on the Saturn as well. I'm taking it as far as I can looking fairly stock for the most part before I dive into the make it uglier than hell mode. :)