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Shifting from 1st to 2nd very early/quickly

ryanlsmith

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For context, I'm in a bit of a unique situation - I just had a shop replace the 3.6L with a brand new 3.6L long block (blew the engine). Transmission was fine/reused. PCM is the original/stock one, not flashed/unlocked.

Engine seems to be running fine, no CEL/codes (except a P1400 which I think is related to swapping the PCM previously, I'm hoping it eventually stops appearing). It's possible that this is a psychological issue, and I'm just going super easy on the pedal, but during slow/rolling acceleration from a stop (especially when I'm behind other cars) it shifts from 1st to 2nd within a second - like only a few hundred RPM past idle. It's usually pretty smooth/barely noticeable and I only realized because there's barely any torque to work with. With slightly more pedal, sometimes I can feel the shift. So far, I've only given it moderate pedal (~50%?) once or twice and it did seem to hold 1st a bit longer like normal, but that's only possible if there is no traffic in front of me.

The shop mentioned they did trigger a transmission re-learn, and I'm wondering if that's what's going on. Curious if this rings any bells to anyone and/or if there is anything worth trying (a new re-learn) and/or if I should be concerned.
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ryanlsmith

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Also, twice now it has felt like it wants to stall in reverse when I try to back into my driveway - right at the curb/going slightly uphill. It seems like the resistance is too much to overcome. I give it gas and it seemed like the RPMs actually dipped. Putting into neutral and trying again seems to fix it...backs up without even giving gas.
 
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ryanlsmith

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Update: I learned/confirmed from Davey that flashing the TCM writes to a separate physical unit. I had thought that the PCM contains both the ECM and TCM - mostly because only the PCM got unlocked/swapped, so I was surprised to learn you can flash the stock TCM.

Reflashing TCM to my original stock file (that I luckily still had) did the trick.
 
 



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