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High Idle 2001 Toyota Tacoma

Discussion in '1st Gen. Tacomas (1995-2004)' started by TacomaMan2001, Mar 17, 2021.

  1. Mar 17, 2021 at 4:57 PM
    #1
    TacomaMan2001

    TacomaMan2001 [OP] New Member

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    Chuck
    Vehicle:
    2001 Toyota Tacoma 2.4 L, 5 Speed Manual Transmission, Extended Cab, 2W Drv
    None
    I have a 2001 Toyota Tacoma, 2.4 L with Manual Transmission with a High Idle.

    I read a number of posts on the site but don't see a clear answer for my problem.

    The problem is: Had Loss of power, Mechanic replaced PVC valve and Idle went up to 1800 and he said IAC valve was bad. Drove home about 8 miles, had good power and Idle was 850-950. When I got home I decided to change the IAC Valve. Cleaned Throttle Body (Mistake) and installed IAC from Amazon. Idle then was surging between 1300 and 1800. Put back the old IAC idle and got a fixed idle at 1800. Somehow got a MAF P0101 Code, cleaned MAF with MAF cleaner and code cleared and Idle came down to 1270. Removed Throttle Body and cleaned and remove slight sticking point at valve close point. Idle came down to 950 to 1050 range, no surging just differ comeback point after revving engine. All pretty good but couldn’t leave it alone wanted 750 on Idle.

    Disconnected battery and shorted Car battery terminals and left it that way for 1 and ½ hours.
    After 1 and ½ hours reconnected Battery and started truck and now idle is around 1800 to 2000.

    Important to note: DID NOT disturbed any hoses ect., touched only the battery terminals and nothing else and Idle changed drastically. Not sure wat to do to bring idle back down??? Any suggestions, thanks.
     
  2. Mar 17, 2021 at 5:00 PM
    #2
    Shortman5

    Shortman5 Well-Known Member

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    TRD S/C, ADS coilovers.
    I’d assume if it’s surging then the TPS should be looked at. I also want to point out that from what I’ve heard that it’s not a good idea to short the wire terminals like that. The air bag module has a battery in it that can be damaged by doing this.
     
  3. Mar 17, 2021 at 5:58 PM
    #3
    TacomaMan2001

    TacomaMan2001 [OP] New Member

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    Male
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    Chuck
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    2001 Toyota Tacoma 2.4 L, 5 Speed Manual Transmission, Extended Cab, 2W Drv
    None
    Thanks I didn't realize that about the airbag I will get it checked as it is very important. Early on I had a TPS code and removed and reinstalled the TPS cable and it cleared the code. I have a FOXWELL NT301 and it does not show any codes. I tried to make it clear that before the shorting the truck battery terminals there was no surging and after the shorting there was no surging but the idle changed from a low idle to a fast steady idle. I did the shorting as it was a recommended as a way to do an Idle relearn for the computer ECU module. Now I have a fast non surging idle idle that was created as a result of shorting the battery terminals.
     
  4. Mar 25, 2021 at 4:11 PM
    #4
    TacomaMan2001

    TacomaMan2001 [OP] New Member

    Joined:
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    Gender:
    Male
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    Chuck
    Vehicle:
    2001 Toyota Tacoma 2.4 L, 5 Speed Manual Transmission, Extended Cab, 2W Drv
    None
    I got the idle down unexpectedly when I did an experiment.

    Using some aluminum tape, I blocked off the hole inside the throttle body that routs air to the IAC valve. I then reconnected all the air ducting and started the engine. It idled around 850. At this point I thought there were two possible explanations. Either the IAC valve was bad, or the computer was not sending commands to the IAC valve. I then remove the aluminum tape inside the throttle body and again reconnected the air ducting and started the engine. To my amazement and joyful surprise, the idle was now under 1000 and in the region of 850 to 950. This must have caused some type of quick idle relearn for the computer as the engine was forced to run on low air and the computer must have stored this data. Things can go way out of whack really quick and come back to normal just as quick. Without the testing capability the dealer has, it’s difficult to figure out things that are being controlled by the computer but in the end, I think some type of idle relearn by the ECU (computer) took place here.
     
  5. Mar 25, 2021 at 4:46 PM
    #5
    Allex95

    Allex95 Well-Known Member

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    allex
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    I have the oppposite thing happen. Cold start rpms at 1k so low. And should be 1500 thinking it might be the ecm I have a extra one might try
     

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