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Preamble

I was looking at a 2009 Land Rover LR3 over the weekend with the OBD Fusion app.

The vehicle had no CEL issues; this was more about thoroughly inspecting a prospective purchase.

I can't remember what protocol was used to connect to the vehicle, but there was no option to view "O2 Sensor 1 Voltage" for either bank - that's the pre-cat sensor.

However, the equivalent wideband PIDs were available for both current and voltage, and I observed they responded to changes in throttle.

This leads me to believe that the LR3 has wideband pre-cat sensors.

What baffled me were the fuel trims

  • Short term fuel trims hovered around +7-8% for both banks regardless of throttle position. Those really should be zero.
  • Long term fuel trims didn't budge from 0% for both banks regardless of throttle position

I have used this app to log fuel trims on a Merc with widebands before, but this is weird.

Questions

  • Does the 2009 Land Rover LR3 really use widebands? If no, why can't I see the PID's for pre-cat O2 voltages?
  • What OBD-II protocol should the app be using to connect to the vehicle?
  • Does anyone have similar experience with questionable fuel trim data?
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  • is there an under hood emissions sticker? that will usually tell you if it's an o2 or afr sensor. also in general stft <= +-9 is acceptable. was the computer reset prior to you looking at it? sometimes that will affect fuel trims until the computer goes into fuel trim learn mode. – Ben Nov 15 '16 at 14:10
  • @Ben don't recall seeing any sticker, I wonder that's a US-specific requirement for manufacturers to put that in? The scanner reported 35 (or was it 65?) warm-ups since the DTC's had last been cleared so I would imagine the vehicle has had enough time to have the fuel trims re-learn themselves. The fuel trim readings were taken immediately after a hot-start; could it have been running in open-loop mode which is why the LTFT's were zero? Also, this LR3 had a 4.4 V8, but felt sluggish under heavy acceleration compared to a 4.0 V6 I had test-driven a week earlier. – Zaid Nov 15 '16 at 15:01

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