Aaron92SE wrote:I believe your drop resistor is located either near the strut as shown in the pic above or underneath the intake air box. Make sure it's plugged in. The guy who owned the car before you could have unplugged it, which gives 100% line pressure providing a very fast shift.
Also, when was the last time you changed your tranny fluid? If you've never done a fluid change, then get a full tranny flush done. It will probably be over $80 to pump out ALL your old fluid and put in new. You can do a drain and fill, but that doesn't change ALL your old fluid. Once you do a flush, then you will do periodic drain and fills to maintain your fluid. When you have bad fluid, it can definitely cause a hard shift. It did in my 92 Maxima when I first bought it in 2001. A tranny flush solved my problem.
Also, bad motor mounts can cause a harsh shift. This is caused when there is no rubber in your motor mount and when shifting from P to R, it can bang into gear. It can also bang into gear in the 1-2 shift if the motor mount is really bad.
And the last thing, look into adjusting your TPS. The throttle position sensor tells the tranny when to shift. If it's adjusted incorrectly, it can cause the tranny to shift VERY hard.
One more thing, it's definitely not your knock sensor. It does not communicate with the TCU at all. I only listens for pinging and tells the ECU to retard timing is nessecary. But it will never cause a hard shift.
for all fourth gen maximas that were automatic the drop resistor is right on the frame of the strut tower. regardless of the model or the year.
also he might have done the drop resistor mod which is this little wiring setup that removes the drop resistor mod for you to have hard shifts but it only works when you punch it
Do your hard shifts occur in regular granny driving or when you hit the pedal hard.
also if it turns out to be that none of this so far is it i agree with aaron on the tranny flush it will be a bit expensive but its worth it of instead of paying 1300 for a good rebuild of your tranny. I might also think about changing the tranny filter if its bad. I paid 120 for teh tranny flush and tranny filter so now you have more or less something to go on if you wanna do it.