Long story short, bought very neglected LR3 (not very good idea) intended to put it back on road for summer road trips.
borrow some space in my brother's in law shop.

After dealing from intermittent starting issues, lost connection issues, and key remote not working finally got everything sorted. (Can help anyone with similar issues, can give details if someone interested).

I'm left with P0171, engine light on and HORRIBLE gas milage (8 MPG)

Over the past 6 month car as been sitting at shop with me trying to sort everything, I started the car every week and idle for while ( could that be issue for poor gas milage? Computer learned "bad habits"?)

For p0171 I trying the obvious, replace spark plugs, clean MAF, new air filter, clean throttle body.. after clearing code engine light comes back after few minutes driving...

Any ideas?

 

Up and down stream O2 sensors

 

Do you think it could be even without any codes related to O2 or cats?

 

They're a possible source of the bad MPG.

Since it's pulling lean, carefully check all the intake tubing for small cracks. It's a common thing and let's unmetered air in fouling the mix up

 

I'm not familiar with live data but I do have a scanner, there is any particular values that I should look for?

Yes I think an air leak is a strong possibility, car is old, tubes get brittle and crack.. I'm really tempted to buy one of those smoke testers from Amazon.

For what I'm reading it could be bad injector or seal but they are expensive, don't want to be throwing money out

 

injectors are really easy to do on these, its legit a 1 hour job and 4 screws. A set of flow tested, cleaned injectors with new gaskets are under $200 on ebay so no worse than new intake tubing.

If it were a leaking injector you'd likely smell fuel under the hood

 

Do not replace downstream sensors. Unrelated to any issues.

2005 usually hav a test port on the fuel rail, check fuel pressure.

Bad injectors - a leaking one would cause rich condition, not lean. One failing to inject would result in a detected misfire more often than not. And you would certainly feel it.

Replace PCV, clean MAF (or replace). Check intake tube for crack downstream of MAF.

 

Never thought on checking injectors on eBay, good tip thanks. I never noticed fuel smell under hood but will keep that in mind anyway..

Got another MAF sensor today, clear the code but came after a few miles again, but for some reason over 50miles on city and highway noticed better gas milage

 

I'm just running cleaner on fuel tank just to make sure injectors are clean, yes I agree on injectors failing completely would misfire and I never got a code for that.

Only think I notice is sometimes under acceleration or idle I see slightly unstable rpms.

Will try to get my hands on smoke test machine to rule out any air leaks

 

Different take on mpg loss... I got an extra 2-3 mpg after replacing trans valve solenoids. Added bonus of no shudder downshifts to 1st gear and smoother shifts across the board.

Does your rig shift into 6th gear?