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  1. #1
    Senior TEAM Member QJKXBM's Avatar
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    Default Removing PZEV Air Pump

    So after installing my non-pzev equipped header, I oped to completely remove the PZEV air pump system. The problem I am having now is that it's throwing a CEL (two codes). The first code is P2258 (Secondary Air Injection Center A Circuit High), and the second is P0172 (Bank 1 running rich). Here is a basic diagram of the setup:





    I am wondering if there is a way to add a resistor for the same ohms as the electric motor to simulate it being there. That way, when the PCM runs that check, it seems like everything is ok, thus not throwing the P2258 code. But, how would I go about getting rid of the P0172 code?

    here's a quick excerpt from the OBD-II Ford manual:

    note: I have a 2005 PZEV focus, which does not use air metered by the MAF to inject into the exhaust manifold

    The vehicles which use secondary air in the 2006 MY are the 2.0L PZEV Focus and the 2.3L PZEV Fusion. Both use a system with ported air. This means that airflow is delivered to each individual exhaust port. The secondary air pump is energized soon after start-up while the fuel system is in open loop. After the O2 sensors warm up, the secondary air pump may continue to be energized while the fuel system goes into closed loop fuel. The secondary air system may continue to run in closed loop fuel until the air pump is de-energized. The typical time period during which the AIR pump is energized is approximately 5 to 12 seconds.

    In order to meet the 2006 MY monitoring requirements, the air pump inlet hose was routed so as to draw in airflow that has been metered by the Mass Air Flow (MAF) sensor. When the air pump is energized, the MAF sensor will show a corresponding increase in air flow. The AIR pump flow check monitors the MAF sensor signal and two air flow models during normal secondary air system operation to determine if secondary air is being delivered into the exhaust system. The air pump flow test compares the actual change in MAF during the pump on and off transitions to the expected change in air flow from the secondary air flow model. (A throttle body flow model is used to "zero out" errors in the air meter and to compensate for off idle driving conditions.) The actual air flow is divided by the expected air flow to calculate an "On flow ratio" and an "Off flow ratio". A flow ratio that is much less than 1.0 means that the air pump has no/low flow, or the inlet hose to the pump is disconnected. If secondary air system operation extends into closed loop fuel, fuel trim feedback is used to discriminate between
    low pump flow and inlet hose disconnection. A low flow ratio with a lean fuel system indicates a disconnected inlet hose. A flow ratio much higher than 1.0 (and a rich fuel system indication) means that the outlet hose from the pump is disconnected.


    If anything, perhaps Focus Sport could answer whether a tune can disable this check.

  2. #2
    Egz
    Egz is offline
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    Default Re: Removing PZEV Air Pump

    In short, the ECU is looking for a 'lean' exhaust when the air pump is on. Since you have a 2005, there is no check on the MAF; it basically is saying "Hmm, I told the air pump to turn on, and the exhaust hasn't leaned out yet..."

    The only way I know how to get around that is through a tune, and have the air pump system turned off. That will solve both of those codes.

  3. #3
    Senior TEAM Member QJKXBM's Avatar
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    Default Re: Removing PZEV Air Pump

    Quote Originally Posted by Egz
    In short, the ECU is looking for a 'lean' exhaust when the air pump is on. Since you have a 2005, there is no check on the MAF; it basically is saying "Hmm, I told the air pump to turn on, and the exhaust hasn't leaned out yet..."

    The only way I know how to get around that is through a tune, and have the air pump system turned off. That will solve both of those codes.

    But it will only check for this "lean" exhaust once it's in closed loop, not open. Perhaps there would be a way to get the PCM to turn off the air pump before going into closed loop fuel?

  4. #4
    Don't Call Me Gaga!
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    Default Re: Removing PZEV Air Pump

    A tune can indeed disable the code, and FocusSport does know how to do it. I have the air pump removed from our FSP car.

    As for other electrical and/or mechanical work-arounds.... I'm not sure what would be the best way to approach that.
    I have too many cars.


 

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