P0171 System Too Lean (Bank 1) - Page 2
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This is a discussion on P0171 System Too Lean (Bank 1) within the General Maintenance, Troubleshooting & Accidents. forums, part of the Tech & Modifying & General Repairs category; Thats how they both work (MAF & MAP) in closed loop. Openloop does not use O2 sensor feedback. You might ...

  1. #16
    Moderator Donkey's Avatar
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    Thats how they both work (MAF & MAP) in closed loop. Openloop does not use O2 sensor feedback. You might want to think about taking this car to a professional.............
    Resident Adviser @ WTF Tuning, LLC
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  3. #17
    Registered User BrandonPaquette's Avatar
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    So map is closed loop?
    Brandon Paquette

  4. #18
    Moderator Donkey's Avatar
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    Quote Originally Posted by BrandonPaquette View Post
    So map is closed loop?
    No..........both MAF and MAP use both closed and openloop fueling. At idle and part throttle you are in closed loop for best fuel economy and emissions. At W.O.T. you go into Openloop fueling. Difference with the Subaru is the ECU now thinks your MAF is broken and now is using the "limp" mapping for fueling and timing. You are technically in a lower state of tune when defauled to the MAP sensor. Google might help explain more about OP/CL fueling.........
    Last edited by Donkey; 02-03-2010 at 08:10 AM.
    Resident Adviser @ WTF Tuning, LLC
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