2004 Maxima RPM Drop During Downshifting

[jaydaniels]

I just purchased my 2004 Nissan Maxima and have 68K miles. I am having a problem where the RPM gauge drops down to idle speed (i.e. 750rpm) and then returns back to a "normal" RPM speed when the transmission is performing its downshift from 5th to 4th gear. (i.e. It appears that the engine loses speed and then jumps back up). The problem does not happen all of the time and only happens during the 5th to 4th transition. Ultimately, when I let my foot off of the accelerator (i.e car has shifted up into 5th gear) and coast, the engine RPM's drop momentarily during the gear change.

I can tell when the strange downshifting will occur by observing the RPM speed when I let off of the accelerator ( in order to coast down through gears 4,3,2,1). Here are the two scenarios: Sometimes when I let off of the accelerator, the tachometer reads 2000 RPM then the engine slows down to idle speed. And sometimes when I let off of the accelerator the RPM immediately reads 1000RPM and slows to down to idle speed. I have learned that the drop in RPM ONLY occurs when the engine starts out at 2000RPM when I off of the accelerator. During this (2000RPM) scenario, the engine is typically at about 1500rpm at the shift point, and here is where the momentary drop from 1500rpm to 750rpm and back up to 1500rpm is seen.


The strange thing is that I am able to override this condition that I am able to foresee. Here is how I override it so it does not occur (and downshift normally): When I let off of gas in 5th gear and see that the engine is at 2000RPM, I can tap on the gas pedal to rev the engine slightly (and jerk my car a little). When I rev the engine slightly, the engine speed reduces down to the 1000rpm point and the strange downshift doesn't happen.

Since I am able to override it, I am not sure if I have a transmisstion problem, a damaged hose, or a faulty sensor of some sort. I took it to autozone to have my codes read (the connector under the steering column) and nothing came back. I had the transmission fluid flushed because of this problem but the problem still exists. Not sure if the dealer would be able to diagnose this one but that is my next step since I have yet to find a mechanic that can solve this one. STRANGE ISN'T IT!! ..

[jaydaniels]

I have clarified this posting. So if you have read this once before, please take time to read it once again. Thanks!