3

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?
Improve this question
2
  • 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, 2016 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, 2016 at 15:01

0

Reset to default

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Browse other questions tagged or ask your own question.