I've recently got an OBD scanner and have found some of the live data streams to be very useful, I was monitoring the timing advance value and observed it fluctuating at idle by 10 deg or so the range was around (10-20) deg. I then wanted to know what was typical, what should the mean value be at idle, what should the range be etc. but I can't seem to find any information regarding what these numbers should be for any sensor, I would have thought manufacturers have a spec sheet with all these numbers so they can diagnose and fault find.

  1. Where would I find this information if it is available?
  2. If this isn't easily obtained, how are we supposed to know the values are ok?

I have a Peugeot 308 (07-12 reg)

  • Most of this info is crowd-sourced, some has been leaked by garage employees. There is usually no official source without access to the official tools. A good OBD app will have sourced more than a poor one - that's about as good as it gets, I'm afraid.
    – Tetsujin
    Apr 25 at 14:31
  • If this is a petrol vehicle with EFI, programming is fixed. Sensors (throttle, map, coolant, O2, knock) send signals in a dynamic (live) operating range. The engine computer determines spark advance/retard for best performance. Values may be in aftermarket or factory service manuals. Since values for each sensor are fixed in programming, nothing can be done to alter them unless the vehicle allows 'tuning' with aftermarket software. If the vehicle is operating within emissions and periodic maintenance, fuel mileage is correct, observing live data from an OBD II reader is a learning curve.
    – F Dryer
    Apr 30 at 23:45


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