Ford 5.4L system lean bank 1 and 2

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  • #11072 Reply


    I have been working on two 5.4’s one is a 98 the other is a 01. They are both throwing sytem lean bank 1 system lean bank 2 codes. The following has all been replaced: o2 sensors, tps, mas, mav, fuel filters, air filters, pcv. I think thats all. At an Idle it sounds like They have a wicked cam and stall converter. Occasionally the idle jumps to 2000 and holds. Once you give them any amount of gas they run perfect. Any Ideas????

  • #12653 Reply

    Car Pros


    Has to be a vacuum leak somewhere. Check intake gaskets, vacuum hoses, valve cover, pcv system, etc. Anyplace that added air can enter the intake system. When you give it gas, you’re compensating for the extra airflow so it would run fine. The choppy idle is a definite symptom of a lean condition. Possibly even a stuck closed fuel injector. Good luck!

  • #13698 Reply


    On mine I haven’t been able to locate any leaks. Haven’t had time to check the other one. If I am unable to find any vacuum leaks is there anything else it could possibly be.

  • #13699 Reply

    Car Pros

    Like I said before, there is the possibility of an injector problem, but they way you say it idles and goes up it sure seems like a lean problem caused by a vacuum leak. You might want to take a fuel sample as well and look for excessive water or ‘other’ things that shouldn’t be in there.

  • #11069 Reply


    I have a 2006 Ford E-150 with 195000 miles.just taken for engine wash and developed accelerating malfunction. It can start with unsteady idle but cannot accelerate scan codes are p2112, p2104, p0222, po708, po122, p2110, p2101. I had to buy a new Accelerator Assembly and a used Throttle body.

    It starts and now idle fine with codes p2112 and p2104 left but cannot accelerate. All wiring and fuses have been checked to be ok and another PCM have been used to test but the engine power is still low. Even the fuel pump have been changed,and if you put on ignition without starting the engine and press the accelerator pedal,the throttle plate opens smoothly but once you start it will close. Please help me out of this limp home mode.

  • #12718 Reply



    Your first mistake was getting a used throttle body. You’re going to have to purchase a new one in order for your problem to be taken care of. Then the idle will need to be relearned and everything will be fine.

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