I have a '00 XKR and am getting codes 171 and 174 meaning the engine is running lean.

I have an OBD2 scanner and installed Torque on my Android phone so I can do the "spray method" of finding where the air leak might be.

However, the Fuel Trim sensor readings on Torque are a constant 0. The O2 sensor display, however, registers values.

I've seen at least one video where people show the STFT display and how it changes if something is sprayed near the leak. What am I missing?

I visually inspected the intake valve, breather hose and they seem in really good shape. The part-load valve is also clear. Any suggestions?

The dealer said I should replace the valves, seal and hose, but they look fine. Should I just do it anyway?

 

You might consider doing a smoke test, search the forum there are a number of threads on doing so and how to create you own 'smoke gun'. This should help narrow it down.

 

Perhaps try another scanner...this does not sounds right. Are long term trims also zero?

 

Maybe it's so bad it's running open loop? (Check status.)

 

Do not replace parts just because the dealer says to. That is the way they do repairs, throwing parts at the car until the problem goes away. Not cost effective.

 

That's just it - I don't get long term fuel trim as even an option in Torque. Maybe it is because I am using the free version? Maybe I need a bedder scanner.

 

No, it is running in closed loop (using O2 sensors). Thanks for the suggestion though.

 

I agree, but seem to have little choice. I ordered the parts ($100) and will replace them even though they look good. If it doesn't work, on to a smoke test or something else.

 

What does freeze frame data show? Won't be ltft zero! If it is, use another OBD tool.