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Thread: What exactly is crank relearn?

  1. #1
    Join Date
    Apr 2008
    Location
    Corbin,Ky
    Posts
    70

    What exactly is crank relearn?

    I am thinking about getting a tune from nelson but seems like you have to do the crank relear alot on my year model. Exactly what is that and why do you have to do it? Will the truck run without doing it?

  2. #2
    The Crankshaft Position (CKP) sensor sends pulses to the PCM as the reluctor wheel teeth rotate past the CKP sensor. The PCM uses the CKP pulses to synchronize the ignition and fuel injector operation, and to time the interval between each CKP pulse. The PCM determines when an excessive change in crankshaft speed occurs by comparing each new time interval with the previous interval. A misfire causes an unexpected change in the crankshaft speed. A certain amount of acceleration/deceleration is expected between each firing stroke, but if the crankshaft speed changes more than an expected amount, the PCM interprets this as a misfire. The interval between CKP sensor pulses is extremely small. At high engine speeds, slight variations in the following components make misfire detection difficult

  3. #3
    And yes the truck will run just a little rough and you wont get the most out of your tune.

  4. #4
    Join Date
    Apr 2008
    Location
    Corbin,Ky
    Posts
    70
    O.k. Thanks for the info. Can any dealership do the crank relearn?

  5. #5
    Yea as long as they have a tech ll but it will cost 80 to 90 bucks for a 5 min job. Yea Ino stupid. if you have a bud with efilive he could do it for you for free.

  6. #6
    Join Date
    Mar 2009
    Location
    Cromwell, CT
    Posts
    256
    any garage with a snap on mt2500 or a otc genisys or similar can do the crank relearn.
    01 ecsb 5.3 4x4 z71
    Avalanche 17s and a pant load of miles

    61 Corvette
    350, 4 speed, 4.56's

    32 Ford 4 door sedan
    keeping it "stockish"

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