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Question about PCM and tranny


meck

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I’ve just swapped a ’97 3.0 v-6 with 4r44e transmission from one ranger to another. The donor engine/tran was running and shifting great when I bought it (I drove it several times for quite a few miles). Now that it is in, the transmission is shifting late and shifts are hard. My question: does the pcm have to relearn the tranny shift points etc. the way it (the pcm) has to relearn the engine strategy? I’ve only driven it a few miles, and it did seem to improve some, but I wanted to check before driving more and maybe causing some damage.
 


RonD

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Reads like PCM is in transmission "Limp mode", you don't have a Check Engine Light(CEL) on right?
And CEL is working?

PCM will go into Limp mode for a number of reasons, but you will almost always get a CEL and code for why.
Limp mode is actually better for the transmission, no slippage, hard shifts and higher RPMs so less Load
 

meck

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Automatic
The CEL is working, but it is not on. My scanner shows no codes, either set or conditional. I hesitate to start serious testing and tearing into the tran. when it was working so great when I removed it from the donor truck. I think I'm going to drive it some more and see if I can get a clearer picture of its symptoms.

Thanks for your reply.
 
Craig0320

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Break it right the first time. Fix it better the next time.
Your throttle body might be really dirty and causing the hard shifts. Pull it and clean it real well. I have seen many of them needed to be cleaned after a new battery install or complete power loss. The pcm resets back to factory and the dirty tb screws with the air flow. I have seen both hard shifting and low to no idle conditions with a/c on after a battery swap out. Also, check your air filter for obstructions and dirt. My step-dad's buick started shifting hard and the air filter was dirty.
 
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