Originally Posted by feta_mgp
OP what OBD2 tool are you using to get this information? I'd like to try it out as well.
I'm using a bluetooth ELM327 tool (less than $20 , Mini ELM327 is ~$15) to read the data and wOBD to log it to a file ( http://www.obd2crazy.com/software.html
You just pair the device with your laptop (USB bluetooth adapters are cheap as well) using the password "0000" or "1234" or "9999". It will assign it a COM port (COM6, etc) which you can check by clicking properties once it's paired. Open wOBD and set the com port on the bottom.
With wOBD there's a Data Acquisition section. Go to the Polling Designer and keep Engine RPM and Vehicle Speed, delete the rest. Set the poll frequency to 1 (approx 3 times a second). Click save then go to the polling screen.
Set the max poll loops to 99999 and click save then reset. You should be able to click start polling and collect data. If the values don't populate within ~10 seconds, click stop, reset, and wait 30 seconds and try again. Once the RPM is reading >800 then you can start driving.
After you've done your driving, click export and it will make a .log file. Open that file with a text editor and you can copy the columns of data into excel or something else (openoffice, google docs, windows live office). I delete the time column and add in a new one called "index" that just increases from 1 to the end of the data set since the time doesn't have sub-second accuracy. I add another column that's speed/RPM for the ratio and plot both on an XY scatter by selecting index, speed, and the ratio column. Click the 2nd data set (red boxes) and right click, format properties or similar then change its axis to secondary.
At that point I just make the graph really wide by zooming out so it's not so compressed in the X-axis and take screenshots of the interesting parts.