Excluding PID's

[gplracerx]

Can I exclude PID's that I'm not interested in, like intake air temp, fuel level and MAF, and get a faster and more reliable update rate for, say, the BT1 dongle? I really only want RPM, wheel speed, throttle and maybe coolant temp.

[Harry]

Yes, please just use the Expert Settings -> OBD Tweaks -> Exclude PIDs field. The value needs to be a list of 4 digit PID description each made um from the mode and the pid as a two digit hex character. Any value entered in a different format will make LapTimer ignore the setting completely.

Samples:

010F -> will not request intake air temperature
010F012F -> will not request intake air temperature and not request fuel level

A list of PIDs is available here: http://en.wikipedia.org/wiki/OBD-II_PIDs

Please note LapTimer requests PIDs at different frequencies. Only removing one of MAF, RPM, TPS, MAP, VSS will have a significant impact on the update rate. All others are requested at lower frequencies and removing them will have a minor impact on update rates. Removing MAP for vehicles without a super/turbocharged engine is not necessary, it is excluded automatically (or not available anyway).

- Harry

[bleunetizen]

what does MAF / IAT reading do for LapTimer? Are these just for logging purpose for reviewing the log files etc or will excluding these affect any features or stability of LapTimer?

My OBD2 reader reports 4 or 5hz without any exclusions, and my log shows its logging 0 for MAP, FUEL and OIL CELCIUS . is it still eating up the bandwidth of the OBD2 and better off excluding them? or does the 0 in the log mean they are excluded already automatically?

[Harry]

You can check the PIDs requested for your car by changing into Sensors List, select the OBD sensor (while connected with engine running or at last ignition on), and press Info. Create a snapshot of this busy page as it will go away after a few seconds. LapTimer requests only PIDs provided by the car, values not available usually show zero.

Removing fuel and temperatures does not help a lot as this values are requested at very low rates. It will not be more than 1 or 2 percent improvement. MAF can make a little more but is not in the high update rate group either. MAF and IAT are used for power and fuel consumption calculation. Neither MAF nor IAT are mission critical.

- Harry

[bleunetizen]

Thanks Harry,

Does that mean I can remove all the PID's that I do not have to log and possibly improve the refresh rate?

I think I only need to know RPM, Speed and Throttle.

Also is there a way to remove the fuel gauge from the overlay ? The fuel gauge does not work for me so might as well just have it removed if possible..


Thanks

[Harry]

Yes, you can exclude whatever you want. But even if you remove all PIDs except the three named, you will not get a lot better update rates. The only PIDs requested at high rates are RPM, Speed, Throttle and MAP. As long as you do not have a super charged engine, MAP isn't requested either. So everything you exclude will be a low priority PID requested only every 16th cycle (MAF every 4th cycle)...

- Harry