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Prius Not Running Well after Throttle Body Cleaning

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by Adam Dellinger, Jul 7, 2019.

  1. Adam Dellinger

    Adam Dellinger New Member

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    I have a 2005 Prius with about 177K miles on it. A few days ago the check engine light came on and I got the P0505 code. To address I tried cleaning the throttle body. The YouTube video I watched led me astray by showing the cleaner being sprayed directly on the valve and with no regard to sopping up the cleaner. I then found threads here stating not to flood the throttle body, so I sopped up what I could and then ran the engine, running A/C and revving hoping to pass the excess fluid (not sure if this was a good move). The engine runs, but when idling, the engine revs itself for about a minute at a time with no indication on the screen that it is running. Then it runs normally for 10-15 seconds and the screen shows it powering the battery, then returns to idling again. I took it apart again and the liquid is gone, but the bottom of the throttle body looks dirty. Reading more posts here I found that the service manual recommends not doing what I did because it passes the contaminants downstream, which is what appears to have happened (see attached photo). So, what now?
     

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    #1 Adam Dellinger, Jul 7, 2019
  2. Adam Dellinger

    Adam Dellinger New Member

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    Replying to my own thread. Based on another thread that discussed a high idle speed, I disconnected the negative terminal of the battery from the rear of the vehicle and let it sit about 20 minutes to reset the idle speed. This seems to have solved the problem, with the “revving” issue going away after I reconnected the battery and ran the engine again. I should note that when the car first started, I noticed my battery charge steadily going down and the engine was seemingly not trying to charge it. It for down to two bars before it finally started charging again.

    If anybody else wants to add to this with proper terminology etc, feel free to do so, otherwise this can be considered closed.
     
    #2 Adam Dellinger, Jul 7, 2019
  3. prius_deep

    prius_deep Member

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    THIS IS ABOUT THE REVVING NOT THE CEL

    if you did a good job of cleaning the Throttle Body and it was really dirty your car WILL rev higher for a day or two[unless you want to disconnect the 12v - I have heard people on here say].

    it will be recalibrating the mixture, because before the cleaning it was gaged. when you or anyone clean a really dirty throttle, you will be letting in more air, so the air / gas mixture is changed after cleaning -> high revving. Car computer needs to recalibrate mixture.

    give it day or two. or again if you do not want to wait just disconnect and reconnect the 12v battery[people say].
     
    #3 prius_deep, Jul 7, 2019
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  4. Mendel Leisk

    Mendel Leisk Senior Member

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    You likely flushed some of the intake manifold "bilge" into the combustion chambers, and or fouled injectors and intake manifold? It's at least downstream of the Mass Air Flow sensor, but the Manifold Absolute Pressure sensor is right there, just past the throttle body. Maybe it's fouling?

    The bilge is courtesy of the PCV valve, btw.

    If you're recleaning the throttle body, just spray carb cleaner onto a cloth or q-tips, don't spray directly. For best results lift the throttle body right off, clean both sides thoroughly. Leave the coolant hoses connected.

    Rushed right now, don't have time to check 2nd gen torque values for throttle body, but fwiw: 3rd gen values (2 nuts and 2 bolts) are 7 ft/lb.
     
    #4 Mendel Leisk, Jul 7, 2019
  5. Patrick Wong

    Patrick Wong DIY Enthusiast

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    1. Disconnect the 12V battery negative cable from the body for a few minutes to clear the logged DTC.
    2. Reconnect the battery cable.
    3. Start the Prius and see if it still has the idle control problem.
    4. If it does, first make sure that you do not have any air leaks downstream from the throttle body. For example, check the PCV hoses to make sure they are secure, make sure the engine oil cap is tight, and the oil dipstick is fully inserted. Tightening torque for the throttle body hardware is 15 ft.-lb. If you had removed the throttle body, the gasket should be replaced.
    5. Make sure the wiring harness connector to the throttle motor is secure.
    6. If you still have a problem, use Toyota Techstream (Mini VCI) to see if the throttle position sensor is working properly. The procedure is to disconnect the wiring harness connector, then open the throttle plate by hand. Techstream should show that the value of "THROTTLE POS" is at least 60%. Consult techinfo.toyota.com for more info if you need to do this.
    7. There is no Manifold Absolute Pressure sensor in the 2G and Classic Prius, BTW.
     
    #5 Patrick Wong, Jul 7, 2019
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  6. Mendel Leisk

    Mendel Leisk Senior Member

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    Whoops. :oops:
     
    #6 Mendel Leisk, Jul 8, 2019
  7. Adam Dellinger

    Adam Dellinger New Member

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    Hi all, thank you for your replies. See my response to myself above- disconnecting and reconnecting the battery seems to have worked to address the idle issue, and it is still running fine after a trip last night and a trip to work this morning. The check engine light also has not returned so for the moment, the cleaning seems to have cleared the P0505 code. Also posting before and after of the butterfly valve (the original photo was an “after,” not a “before”). I wasn’t able to get it perfectly clean but I definitely got a lot of gunk off.

    Anything I should be looking for related to potential issues from the contamination that I may have passed along when spraying the cleaner?
     

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    #7 Adam Dellinger, Jul 8, 2019
  8. Patrick Wong

    Patrick Wong DIY Enthusiast

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    The main concern is whether dirty cleaning fluid contaminated the throttle motor. Since the car is running well, do not worry.
     
    #8 Patrick Wong, Jul 8, 2019
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  9. edthefox5

    edthefox5 Senior Member

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    Spray some lubricant on the dried up spring. The motor is struggling to turn that.
     
    #9 edthefox5, Jul 8, 2019
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  10. Adam Dellinger

    Adam Dellinger New Member

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    I did spray some WD-40 on it, since it was all I had on hand. What I was reading recommended a silicone lubricant, which WD-40 is not, but I thought that would be better than nothing.
     
    #10 Adam Dellinger, Jul 9, 2019
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