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Working on a 2000 Toyota Celica GTS with a P0171 but only at a RPM range of 3,000-4,000 RPM's according to the freeze frame data. The short term fuel trim is good, but the long term fuel trim at this higher RPM is +30% to +40%. The individual that owns the car replaced the intake gasket, MAF sensor, & oxygen sensor. We smoked the car and no intake leaks are found. The WOT test is good since the O2 sensor B1S1 reads rich .7vdc to .9vdc. The only after market parts on the car is a aftermarket intake air tube and K & N air filter. Any help is greatly appreciated.
Perform a volumetric efficiency test. Do a wide open throttle in 1st gear graph the maf g/s intake air temp, engine rpm and engine liter size. Report back with numbers. Also these things are known for fuel injector issues. Take fuel alcohol content sample.
