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Discussion Starter · #1 ·
I just completed a complete swap of a (what I think is) a 2003 motor into my 2005 MDX. She has been sitting for a couple of years after a freak accident where the serpentine belt broke and wrapped itself around the crank. I let her sit in the driveway forever and was getting ready for the junk heap. My daughter needs a car and I thought... What about the MDX? Last week got a low miles used engine/transmission from JDM. Transferred all components I could from the old motor that I know to be new (including brand new timing belt). Had a few codes initially that seemed to be related to the barometric pressure. This morning I transferred the throttle body and now reading zero codes!

Any suggestions about upgrades or anything I should do to insure this marriage between the ECM and motor continues and I have a very long life on this "new" car? The shifting seems different, especially second gear. She gets almost to 5K before shifting which I'm told is normal for a 2003 transmission.

thanks in advance for your comments.
 

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5,000 rpm is too high, though the "improved" mapping did raise the normal shift point considerably. With a light throttle, I was getting shifts in the 2500-3000 rpm range (still too high, IMHO). If you have a lead foot, shifting well over 4,000 rpm wouldn't be unusual (I hesitate to use the word "normal" because it really shouldn't be that way, but it is).

Congrats on what appears to be a successful swap though - if you've got no codes, and it's running right, you're probably home free. The new timing belt was a good move, too. I'd take a very close look at the transmission fluid and do a few drain-and-fills if it's dirty. And of course, fluid for the differentials and transfer case are no-brainers.

If you plan to keep the car for quite a few miles / years, AND the handling is loose and funky, I'd suggest doing struts, control arms and probably tie rod ends so that it'll drive a lot like a new car for your daughter for the time she owns it. That's better than waiting 20,000 miles and spending the same money so the car can go to the boneyard with a tight front end. ;-)
 

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Discussion Starter · #3 ·
5,000 rpm is too high, though the "improved" mapping did raise the normal shift point considerably. With a light throttle, I was getting shifts in the 2500-3000 rpm range (still too high, IMHO). If you have a lead foot, shifting well over 4,000 rpm wouldn't be unusual (I hesitate to use the word "normal" because it really shouldn't be that way, but it is).

Congrats on what appears to be a successful swap though - if you've got no codes, and it's running right, you're probably home free. The new timing belt was a good move, too. I'd take a very close look at the transmission fluid and do a few drain-and-fills if it's dirty. And of course, fluid for the differentials and transfer case are no-brainers.

If you plan to keep the car for quite a few miles / years, AND the handling is loose and funky, I'd suggest doing struts, control arms and probably tie rod ends so that it'll drive a lot like a new car for your daughter for the time she owns it. That's better than waiting 20,000 miles and spending the same money so the car can go to the boneyard with a tight front end. ;-)
After the throttle body change and a few drives the shifting seems to have calmed down. not clear why but I'll take it. All fluids new and I plan to dump the transmission fluid tomorrow for an acura style "flush". New suspension ordered (control arms/tie rods and stabilizer bars) the struts are new (although sitting a couple of years). I plan to pump and dump both Differentials tomorrow.

I put on a premium timing belt kit and its so easy to do when the motor is sitting on a driveway. Motor looked super clean and nearly new. Finger's crossed we did everything right...
 

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It makes perfect sense that the shifting is better - the shift point is determined primarily by the reported throttle position, and that was most likely off a bit with the old TB. I actually recalibrated my TB sensor so that it was reporting a lower value at a given throttle opening, to calm down the tendency to shift when crossing a painted line. ;-)
 

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Discussion Starter · #5 ·
It makes perfect sense that the shifting is better - the shift point is determined primarily by the reported throttle position, and that was most likely off a bit with the old TB. I actually recalibrated my TB sensor so that it was reporting a lower value at a given throttle opening, to calm down the tendency to shift when crossing a painted line. ;-)
how is that accomplished? Are you an engineer?
 

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It's been a long time, but IIRC, the throttle position sensor is keyed to allow some rotation for adjustment. I believe I just rotated it so that the sensor would report a higher throttle position (which would signal the transmission to shift sooner). I'm a techie / engineer but this is more mechanical than electrical.
 
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