Scotty, I have an 96 Toyota 4 runner 3.4 sr5. I am at my wits end my fuel trims high, very high like stft Around 17 to 25+% and the left is is about the same closer too there 25% most of the time. Maf is good iat is good 02 not really cycling as they should. I will try too send a pic of the obd findings. https://resources.repairsolutions.com/rs2_pdf/8c8dbc30-28bc-44a0-99e7-80fc53702e69_01012024045941.pdf . And thank you for any help your can give me. Shawn W.
P0171 means the upstream O2 sensor is reporting a lean condition (too much air) in the exhaust. Check for a vacuum leak, check/clean the mass air flow sensor. Have you done any other troubleshooting steps?
More at https://www.obd-codes.com/p0171
Scotty, I have an 96 Toyota 4 runner 3.4 sr5. I am at my wits end my fuel trims high, very high like stft Around 17 to 25+% and the left is is about the same closer too there 25% most of the time. Maf is good iat is good 02 not really cycling as they should. I will try too send a pic of the obd findings. https://resources.repairsolutions.com/rs2_pdf/8c8dbc30-28bc-44a0-99e7-80fc53702e69_01012024045941.pdf . And thank you for any help your can give me. Shawn W.
The computer is detecting more air than should be in the engine, and it's compensating by adding more fuel to the engine. You likely have vacuum leaks if the vacuum hoses are original to the car.
P0171 Fuel System Too Lean (Bank 1)
Just the one code?
look for exhaust leaks, or intake gasket leaks on bank 1
post the long term fuel trims for both banks please.
Shawn, the simple explanation is that you have un-metered air entering the system most likely post MAF. This is the most common cause of high STFT’s. Look for splits in your air intake, vacuum leaks (including mis-routed vacuum hoses), or intake gasket leaks.
Shawn
