Tarago ACR50R P0171 error and engine won't start when hot

[John-Australia]

Hi! We have a 2006 Toyota Tarago ACR50R (see below for more details on the model). The engine light is on and the OBD2 code is P0171 (system too lean bank 1).

We have done the following:

Tested for vacuum leaks - none found. Had a mechanic check this also.

Replaced the following parts - spark plugs, ignition coils, fuel pump assembly, ecu, pcv valve, exhaust manifold (includes catalytic converter), pre cat oxygen sensor, post cat oxygen sensor, maf sensor, air filter, fuel injectors, tappet cover, tappet cover gasket.

When engine is running, the long term fuel trim is +44%, the short term fuel trim is about +5%, the maf sensor reads 1.5g/s.

The car will start immediately when it is cold. However, if you've taken it for a 15min+ drive, turn it off and then try to start it up again, the engine will crank but it won't start up. You can get it started if you unplug the maf sensor connection. For the car to start again (with the maf plugged in) you have to wait until the engine cools down.

Any ideas on what could be causing this issue?

Thanks in advance, John

Specs:

2006 Toyota Tarago GLI ACR50R Wagon Unleaded
Model: ACR50R-GRPDKQ
Engine: 2AZ-FE
Trans./Axle: U241E -02A
Plant/Built: C25 Aug 2006
Kms: 372,000

[Tony Prodigy]

That's a monumental investment in parts shot gunning. I do feel that it's possible if aftermarket parts were used, all it takes is for one or more to be dodgy to recreate the same issue.

What a frustrating experience that must be.

Did you do all the work yourself ?

[CONROD]

Fuel Pressure regulator ?