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Yet another too much PIDS logging lag post.

For my first try at Spa I was using the OBDlink MX as OBDII scan tool, S8 with GPS enabled, Gopro Hero3+ as camera.
Logging as fast channels:
A/F ratio, MAF, RPM, Fuel trim long b1, fuel trim short B1, Oxy B1, Speed, Throttle, Timing advance.
Slow channel : intake air temp.
Ignore pid capabilities disabled, ignore no data disabled.

I imagine speed comes from the GPS.
Overlaying Speed, RPM, throttle position, intake temp and g's I remarked that:
Throttle raw data ranges from 0 to 78: is it usual? After scaling 1-99 : bizarre but I've seen some video with the same scaling: it's a rounding reason?
G's seams to be in late respect the video especially in braking zones.
Speed very often, in transients (acc, decel), is in late too.
Throttle position in late, in advance, sometime misses the gear changes remaining at 99% , sometimes is biased to 3-4-5% instead of 1.

Are these related to the number of channels logged and to the poor quality of the internal GPS?
Why g's are so in late? Anyone is experiencing the same?

A/F ratio is always 1: quite strange... (It should variate...) someone is also experiencing that?

Thank you in advance
Best regards.

P.S. It would be really helpful to implement triggers to start the whole bunch of things for instance when exiting the pit-lane and stopping when entering the pit-lane, there are so many things to do that sometimes I forgot to start the camera, for instance.

P.S.II I have recorded multiple sessions. I see it is possible to add reference laps (one by one) but not to merge sessions (to have the opt lap calculated ). I solved as described here : I think it will be a good idea to put it in the faq (by adding that the app need to be closed and reopened to display the modifications) or to implement a button to merge multiple sessions (already filtered with the same circuit of the main session and maybe already ordered by date-time, having a select all func., or advanced date filtering, stuff like this.. I think someone is starting to hate me. :)


  • P.S.III Seems that is not possible to export in a single vbo file all the laps of all the resumes : is that correct? There is a way to do that manually?
  • So many questions in one post. I do my best to answer all:

    1) Not possible to export all laps as VBO? A: VBO can export only within single "resume", as Circuit Tools application cannot handle the break in the data.

    2) Speed comes from GPS? A: Speed in some parts of the app comes from GPS, but you can also use OBD-II speed for the speedometer in the overlay.

    3) G's and Speed is late? A: The GPS data is late, G's are calculated from the GPS data. There can be noticeable delay between GPS data and OBD-II data especially when using the internal GPS. I will create a feature to re-sync/re-align these two in future. The video delay can be adjusted, but it does not help delay between GPS and OBD-II. An external GPS will help this a lot. My recommendation for the Android OS is Garmin GLO.

    4) AF ratio always 1? A: Your car may not output the value, OR there is a bug. If you send the session to me I can check the raw data recorded. Email the .rcz to tracks(at)

    5) Throttle scaling wrong? A: RaceChrono takes the maximum and minimum within the session. There might be a situation when the scaling does not work, especially at the bottom end. For example when car reports 0% when not running, and when running minimum 5%. RaceChrono takes the 0% as it thinks that's the minimum. Also you might get 99% as visible maximum, as there's been a short while where higher value has been recorded. This will be addressed in future.

  • Thank you Antti. The Garmin arrived the day I was on track : I will test it in August.
    Having slicks the ECU calculation are not in line with reality.
    I sent you an email.

    Best regards
  • After looking at the .VBO file you sent, I think there is bug(s) in the .VBO export it self. There's no decimals for the Air/Fuel ratio for some reason, so it's always 0 or 1... Also the gasoline version of the channel is missing a proper label.
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