I just purchased an RX that had been part of an estate. Replaced all AF and O2 sensors. Replaced MAF. Replaced VVT solenoids. Runs great at idle. Depress pedal slowly and runs fine. Put it under load or depress pedal sharply and runs like crap and displays a P0171 code. Short term fuel trims are negative or 0. Long term fuel trim on Bank 2 is 17. Long term fuel trim on Bank 1 is 38!! Any insight? Thanks!!

 

Replaced with what brand parts? New parts?

 

RX is finicky too .. I would suggest OEM for all sensors/electronic stuff. Also do a hard reset [discoonect battery for 20 mins or so]. A good charged battery and working alternator will ensure you get the right readings and interpretation.

Welcome to the Club Lexus and please elaborate the issue a bit in the title. There is a length limit but a more explicit title will help readers in future as well as get the proper attention from members.

Salim

 

Estate vehicles makes me think of cars that may have been sitting a while.

If car was sitting, may need to clean fuel injectors and add fresh gas.
Looking at your high fuel trims the injectors may be gunked up/sticky or engine may have major vacuum leak, or as others say maybe bad parts you already replaced.

A quick test is to put an index finger on each fuel injector connector and feel it thumping- this won't say whether it is clogged internally or externally at the holes in the nozzle but if one "feels off" maybe get lucky.
PS- if you have to pull the injectors to flush and clean and test them(lots of youtue videos on this) you will probably need new injector gasket kits because your old ones are probably dried out and will leak gas after installlation.