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disconnected battery, idle changed?

Discussion in 'Technical Chat' started by 33yrsoftoys, Oct 12, 2014.

  1. Oct 12, 2014 at 4:56 PM
    #1
    33yrsoftoys

    33yrsoftoys [OP] Over 40yrs now

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    joel
    mid Michigan
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    Bilstein 6112's 5th clip 1/4" spacer driver's side. Icon tubular UCA's with Delta joint, wheelers superbumps, ECGS bushing. Allpro standard leaf packs, 5160's, U bolt flip kit with wheelers super bump's, extended stainless steel brake lines, carrier bearing drop. Icon rebounds 17" with Nitto terra grappler G2's 285/70/17's.
    I disconnected my battery, reconnected it 1/2 hr later and the cold start idle sequence changed? It would start at about 1500rpm, after a minute or so drop to 1250, then 1000 ending up at 700rpm warm. Now, starts at 1700, then 1500 gradually dropping to 700, takes longer though. No change in air temp or humidity. Its a 1013 TRD with a 4.0. Any ideas?
     
  2. Oct 12, 2014 at 5:02 PM
    #2
    RCOTaco

    RCOTaco Long Time Lurker

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    Hamlet, NC
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    When you disconnect the battery, the ECU resets to a basic setup. After a few minutes of idling, or driving, the ECU has an opportunity to react to the feedback that all the sensors like the throttle position sensor, air to fuel sensors, and all the 100 other sensors. Give it a few minutes and it should go back to normal. Nothing to worry about, it'll happen every time you disconnect the battery for a little while.
     
  3. Oct 12, 2014 at 6:37 PM
    #3
    33yrsoftoys

    33yrsoftoys [OP] Over 40yrs now

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    joel
    mid Michigan
    Vehicle:
    2021 dcsb off road 6 speed manual
    Bilstein 6112's 5th clip 1/4" spacer driver's side. Icon tubular UCA's with Delta joint, wheelers superbumps, ECGS bushing. Allpro standard leaf packs, 5160's, U bolt flip kit with wheelers super bump's, extended stainless steel brake lines, carrier bearing drop. Icon rebounds 17" with Nitto terra grappler G2's 285/70/17's.
    Thanks guys. It does raise another question, if it relearns the driver, then wouldn't it be smart to reset the ECU anytime a drivetrain mod is done? A lift, tire size change, exhaust, intake, etc? Let the ECU relearn (its) new format?
     
  4. Oct 16, 2014 at 5:31 AM
    #4
    33yrsoftoys

    33yrsoftoys [OP] Over 40yrs now

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    joel
    mid Michigan
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    2021 dcsb off road 6 speed manual
    Bilstein 6112's 5th clip 1/4" spacer driver's side. Icon tubular UCA's with Delta joint, wheelers superbumps, ECGS bushing. Allpro standard leaf packs, 5160's, U bolt flip kit with wheelers super bump's, extended stainless steel brake lines, carrier bearing drop. Icon rebounds 17" with Nitto terra grappler G2's 285/70/17's.
    Thanks guys. In the process of all this I might have stumbled on something. My truck was one that had a cold start knock. I did a oil change and a battery disconnect in the same day. The cold start knock is 90+% gone. It's was either a faulty oil filter check valve or the computer reset. Either way a BIG plus! I waited a couple of days to post to be sure. I sure hope this helps others.
     
  5. Oct 18, 2014 at 11:48 AM
    #5
    Shadetree

    Shadetree Well-Known Member

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    If you want to save your ECU settings before you disconnect the battery, use a computer or memory settings saver that plugs into an energized cigarette lighter receptacle. Typically they cost less than $10 at an auto parts store. You can also connect a second battery or 12-volt power supply to the cables.
     

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