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2012 GX not getting over 3500 rpm

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  • 2012 GX not getting over 3500 rpm

    this happened now a few times and I have not quite figured out the cause.
    I try to accelerate and the RPM would not go above 3500, no matter if in neutral, or under load. It is really annoying when trying to drive uphill or pass someone on the freeway.
    When I turn the ignition off and back on again it's typically gone - for a day or two (or even months) and then back again. Seems to be more frequent on hot weather days.

    Anyone having the same issue?

  • #2
    is it coding sounds like limp mode check stored codes


    • #3
      My car is doing this to, have you found any solutions? I have Attempted many suggestions. This is my freeze frame. Freeze Frame Report
      Dec 14, 2019 12:29
      VIN retrieved from Vehicle VIN: 19XFB5F58CE001610 Make:Honda Year:2012
      Trouble Code P1129 triggered Freeze Frame.
      PID : Description : Value
      04 05 06 07 0A 0B 0C 0D 0E 0F 10 11 1F 33 42 43 44 45 47 49 4A 4C 51
      : Calculated Engine Load Value : 36.9 % : Engine Coolant Temperature : 194 °F
      : Short Term Fuel Trim Bank 1 : 0.0 %
      : Long Term Fuel Trim Bank 1 : -1.6 %
      : Fuel Pressure (Gauge) : 29.6 PSI
      : Intake Manifold Absolute Pressure : 5.4 PSI : Engine RPM : 1376 rpm
      : Vehicle Speed : 42 MPH
      : Timing Advance for #1 cylinder : -13.0 °
      : Intake Air Temperature : 73 °F
      : Mass Air Flow Rate : 0.9 lb/min
      : Absolute Throttle Position : 15.3 %
      : Run Time Since Engine Start : 306 seconds : Barometric Pressure : 14.6 PSI
      : Control Module Voltage : 13.175 V
      : Absolute Load Value : 25.9 %
      : Commanded Equivalence Ratio : 1.999 λ : Relative Throttle Position : 4.3 %
      : Absolute Throttle Position B : 31.8 %
      : Accelerator Pedal Position D : 18.8 %
      : Accelerator Pedal Position E : 9.4 %
      : Commanded Throttle Actuator : 4.7 %
      This information is provided without warranty and is subject to the Terms of Use posted at Reproduction of this information or any portion thereof constitutes infringement of copyright.
      © Copyright 2019 Page 1 Freeze Frame Report
      Vehicle Protocol: CAN29_500 Sensor F/W Version: OSAPI v2.54 App Version:
      This information is provided without warranty and is subject to the Terms of Use posted at Reproduction of this information or any portion thereof constitutes infringement of copyright.
      © Copyright 2019


      • #4
        Happy to say finally my 2012 Honda Civic GX is running, idling, and no more limp home mode or engine trouble codes.

        What I found.

        Engine Vacuum Low. I attached a vacuum gauge ($22 Amazon) to the PCV hose with a tee. At idle my vacuum was only 14”mhg. Should be around 20”mhg. You can also verify by inserting a push pin in the middle terminal of MAP sensor connector and measuring output voltage of MAP sensor. With key on engine off you should measure 2.9 volts. At idle 900 rpm should be less than 1 volt. Like .8 .9 volts. Mine was at 1.6 volts idling.

        The ECM watches the MAP sensor on deceleration (foot off the pedal) and is looking for less than 1 volt for period of time. If it does not see this it goes into Limp Home Mode and sets a P1129 code. Unexpected high voltage MAP Sensor. My car also had a rough idle when cold. This would smooth out after the engine warmed up, usually pretty quick.

        The dealer had adjusted valves trying to solve rough idle, so I wasn’t suspecting valve adjustment but after verifying no vacuum leaks and pcv valve was good. I decided to check valve adjustments again.

        I found the exhaust valves were all too tight. They are supposed to be .009 to .010 I could get a .007 to slip in between. After adjusting all the valves which was super simple. My engine is again purring like a kitten vacuum is back and rough idle when cold is gone no more limp home mode or check engine lights. Yippee.

        Moral of the story. Adjust your valves every 30k. Honda makes it real easy to do your self. Single overhead cam gear has numbers in casting . “Up” is number one. 2, 3, 4 not in that order, just remove spark plugs to make engine turn easy. Line the numbers up on top. Then adjust intake and exhaust on that cylinder that’s currently on top of cam gear. I did with the engine cold. Turning the wheel hard to right you can use a socket wrench through hole in fender well to Rotate engine crank shaft. It’s easier to do with a helper. Look up specs in Honda book don’t believe everything you read on the internet when it comes to specs. I have been misinformed before.


        • #5
          Yep, precision valve adjustment makes a big difference, but adjusting valves is much easier to do than that. To adjust valves on ANY four stroke engine, use the simple "intake closing/ exhaust opening" method. Using a socket & ratchet wrench on the front damper/pulley, rotate the crankshaft in the normal direction (counterclockwise on Honda). When the exhaust valve(s) start to open, adjust the intake valve(s). When the intake valves are almost closed, adjust the exhaust. This method is much, much easier than the service manual recommends.