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  • Re: P0171 bank 1 too lean

    From retired1@21:1/5 to Isaac Montara on Thu Feb 27 20:45:34 2025
    XPost: alt.home.repair

    On 2/27/25 7:45 PM, Isaac Montara wrote:
    I have a Mitsubishi Lancer ES early 2000s with a P0171 that keeps coming
    back after I reset it with an OBDII hand-held code reading tool.

    I put new spark plugs in and it still sets the P0171 bank 1 too lean.
    When it idles, it often kills the motor so it's not getting enough fuel I think.

    But I don't know cars all that well. How do I increase the idle RPM on
    an early 2000s Lancer ES?

    Have you tried putting a fuel system cleaner in the gas tank, and then
    driving the car for awhile to see if code stops ?

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  • From AMuzi@21:1/5 to Isaac Montara on Thu Feb 27 20:01:31 2025
    XPost: alt.home.repair

    On 2/27/2025 6:45 PM, Isaac Montara wrote:
    I have a Mitsubishi Lancer ES early 2000s with a P0171 that
    keeps coming
    back after I reset it with an OBDII hand-held code reading
    tool.

    I put new spark plugs in and it still sets the P0171 bank 1
    too lean.
    When it idles, it often kills the motor so it's not getting
    enough fuel I
    think.

    But I don't know cars all that well. How do I increase the
    idle RPM on an early 2000s Lancer ES?

    This guy covered the usual items for 'lean bank'

    PCM software needs to be updated
    Vacuum leaks (Intake Manifold Gaskets, vacuum hoses, PCV
    hoses, etc.)
    Mass Airflow Sensor (MAF)
    Plugged Fuel Filter or weak Fuel Pump
    Plugged or dirty Fuel Injectors

    without success but then discovered an unusual failure:

    https://www.clublexus.com/forums/rx-2nd-gen-2004-2009/671879-finally-solved-p0171-and-p0174-codes.html

    --
    Andrew Muzi
    am@yellowjersey.org
    Open every day since 1 April, 1971

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  • From Xeno@21:1/5 to Isaac Montara on Fri Feb 28 13:22:23 2025
    XPost: alt.home.repair

    On 28/2/2025 11:45 am, Isaac Montara wrote:
    I have a Mitsubishi Lancer ES early 2000s with a P0171 that keeps coming
    back after I reset it with an OBDII hand-held code reading tool.

    I put new spark plugs in and it still sets the P0171 bank 1 too lean.
    When it idles, it often kills the motor so it's not getting enough fuel I think.

    But I don't know cars all that well. How do I increase the idle RPM on
    an early 2000s Lancer ES?

    If you have a definite P0171 DTC, then best you determine why Bank 1 is
    being deemed too lean. The DTC alone is providing insufficient data -
    it's a diagnostic starting point, nothing more. An intake system air
    leak can cause such an issue so look at the intake system carefully for
    cracked hoses and/or loose hoses or ducting. So can partially blocked injectors. Take a look at LTFT and STFT data. Look at live data, look at
    freeze frame PIDs. A 20+ year old car is likely to have perished hoses
    and ducting and can be a PITA to locate when they become the cause of
    air leaks.

    If you aren't familiar with OBD2 data, consult someone who is. You need
    to know what data is *normal* and what data is *within spec*

    Dicking with the idle speed *will not fix the issue*. The idle speed is
    merely a symptom of idle air enleanment, not the cause.

    --
    Xeno


    Nothing astonishes Noddy so much as common sense and plain dealing.
    (with apologies to Ralph Waldo Emerson)

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  • From Scott Dorsey@21:1/5 to IsaacMontara@nospam.com on Fri Feb 28 15:52:12 2025
    XPost: alt.home.repair

    Isaac Montara <IsaacMontara@nospam.com> wrote:
    I have a Mitsubishi Lancer ES early 2000s with a P0171 that keeps coming
    back after I reset it with an OBDII hand-held code reading tool.

    I put new spark plugs in and it still sets the P0171 bank 1 too lean.
    When it idles, it often kills the motor so it's not getting enough fuel I >think.

    Why plugs? That's not likely to be related in any way, it is not like you
    are getting a spark error.

    Your first job is to figure out if it really IS too lean or if the computer
    is deluded.

    You need a real scan tool so you can see if the other bank is being
    forced too rich or not.

    With an inline engine where everything is one bank you can smell the
    exhaust and tell if it's too rich or too lean, but you're going to need
    the proper tool for this one.

    How do I increase the idle RPM on an early 2000s Lancer ES?

    Why would you want to increase the idle RPM? If the engine really IS
    running too lean, that's a good way to burn some valves. On the other
    hand if the engine is running rich and the computer thinks it's too
    lean, that also does nothing to help the problem.
    --scott
    --
    "C'est un Nagra. C'est suisse, et tres, tres precis."

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  • From Xeno@21:1/5 to AMuzi on Sat Mar 1 11:36:56 2025
    XPost: alt.home.repair

    On 28/2/2025 1:01 pm, AMuzi wrote:
    On 2/27/2025 6:45 PM, Isaac Montara wrote:
    I have a Mitsubishi Lancer ES early 2000s with a P0171 that keeps coming
    back after I reset it with an OBDII hand-held code reading tool.

    I put new spark plugs in and it still sets the P0171 bank 1 too lean.
    When it idles, it often kills the motor so it's not getting enough fuel I
    think.

    But I don't know cars all that well. How do I increase the idle RPM on
    an early 2000s Lancer ES?

    This guy covered the usual items for 'lean bank'

    PCM software needs to be updated
    Vacuum leaks (Intake Manifold Gaskets, vacuum hoses, PCV hoses, etc.)
    Mass Airflow Sensor (MAF)
    Plugged Fuel Filter or weak Fuel Pump
    Plugged or dirty Fuel Injectors

    without success but then discovered an unusual failure:

    https://www.clublexus.com/forums/rx-2nd-gen-2004-2009/671879-finally- solved-p0171-and-p0174-codes.html

    Interesting story and there are many like this. But the dealer scan
    tools should have been able to test for it. Look up OBD2 Mode $08 -
    control operations of on-board systems. Mode $08 allows the tech to
    control certain operations of the EMS allowing a scan tool to do
    bidirectional control of an onboard system or test. Most solenoids and
    emission equipment can be controlled and cycled independently of
    conditions and commands. Factory scan tools and the more expensive
    aftermarket scanners offer bi-directional functionality thus have Mode
    $08 capabilities. This is a very handy method of testing for equipment
    failure without the need to wait for the EMS to command the operation.
    Would have been very handy for you, no need to wait out the time or an
    idle situation.

    HTH

    --
    Xeno


    Nothing astonishes Noddy so much as common sense and plain dealing.
    (with apologies to Ralph Waldo Emerson)

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Isaac Montara@21:1/5 to All on Thu Feb 27 19:45:52 2025
    XPost: alt.home.repair

    I have a Mitsubishi Lancer ES early 2000s with a P0171 that keeps coming
    back after I reset it with an OBDII hand-held code reading tool.

    I put new spark plugs in and it still sets the P0171 bank 1 too lean.
    When it idles, it often kills the motor so it's not getting enough fuel I think.

    But I don't know cars all that well.
    How do I increase the idle RPM on an early 2000s Lancer ES?

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)