Issue with throttle

[kuklinsk]

Using Laptimer I've had issues getting an accurate read on my throttle. Below is the first 30 seconds of a recent lap. You'll see the throttle goes up to 2.33 and I know I never pushed the throttle all the way to the floor. When using other apps (like FuzzyCar) I seem to be able to get a more accurate measure of throttle response so I don't think its my car or the Kiwi module. Any idea what the problem may be?


TIME_LAP THROTTLE
0 2.33
0.63 0
1.36 2.33
2.66 2.33
3.69 2.33
4.77 0.06
5.62 0.16
6.39 0.25
7.62 2.33
8.6 0.16
9.62 0.23
10.36 0.1
11.37 0
12.37 2.33
13.61 2.33
14.39 2.33
15.6 2.33
16.63 2.33
17.41 2.33
18.63 0.29
19.62 0.29
20.63 0.29
21.4 0.29
22.58 0.29
23.4 0.19
24.64 0.12
25.64 0.1
26.5 0.12
27.48 0.12
28.63 2.33
29.65 2.33
30.66 2.33

[Harry]

Throttle is a difficult topic to deal with as cars often deliver values outside spec here. I assume in your case LapTimer receives some non standard values too and does not handle them correctly (overflow). Do you have this pattern for all of your laps or does it go away for later laps (after having started LapTimer)?

The story behind is as follows:

The OBD II spec says that cars should deliver values between 0 and 255 for the current throttle position. This range of A = 0 to 255 is mapped to 0 to 100%. So usually, you just take the value A delivered by the car, divide by 255 and multiply by 100%.

throttle% = A / 255 * 100%

Problem is, I have never seen a car delivering this range. Instead they deliver (for example) values between 8 and 122 or something like that. What LapTimer does is monitoring the min and max value delivered since the OBD has been connected and applying this min and max values to normalize the value A to 0 to 100%. So we do something like

throttle% = (A-minValue) / (maxValue-minValue) * 100%

The 2.33 values mean LapTimer has derived a 233% throttle position, which should not happen except there are invalid values in minValue and maxValue...

I will check the routine and add some range checking on top.

- Harry

[kuklinsk]

Yes this occurs on all my laps and I am sure that during this specific lap I never floored the throttle, probably only got upto maybe 50%. so I'm not sure why it is showing up as 2.33.

Thanks for the help!