OBDII data question,
12-13-2011, 12:15 PM
#17
Race Director
You can't capture brake pressure through OBD2. You have to have a stand alone accelerometer to capture deceleration rates. If you hook into the brake pedal switch, you only have "on/off" information.
OBD2 does output throttle position by the voltage from the potentiometer at the gas pedal. Interestingly enough, my car only does "99.7%" throttle with the pedal to the floor.
OBD2 does output throttle position by the voltage from the potentiometer at the gas pedal. Interestingly enough, my car only does "99.7%" throttle with the pedal to the floor.
I do not have my references handy that explains this but if you want pm me and when I get back to my office I can reply with the math.
Sincerely,
Macster.
12-13-2011, 12:20 PM
#18
Race Director
I currently run a RacePak IQ3 dash in my 996 GT3 racecar for data collection and a consolidated easy to read display. One bit on information that I have been missing out on is the brake and gas pedal input pressure, due to the complicity of setting up the capture mechanisms. RacePak just announced they will have a universal OBDII module that will plug directly into the IQ3 dash for data collection but it is not cheap. So my question is, whether or not it is even possible to capture brake and gas pedal pressure from the GT3 OBDII port?
Brake pedal pressure, brake system hydraulic pressure, is not a standard OBD2 parameter. It might be available using a special query or perhaps available on another bus, from another controller. I have not done any research into this for Porsches so I can't say for sure.
Speed is available from the OBD2 port and this can be used to calculate g's of acceleration/braking. Also, of course a 3 axis accelerometer can be used but this involves more math.
Sincerely,
Macster.
