Here's an interesting phenomenon with my auto Max. Please try this with yours and see if it does it also.

Try driving at highway speeds. Turn off your overdrive and your car will change gears and the revs go up. Now punch it. If you are going fast enough, the car won't try to shift down into second. Now while you are accelerating, push the overdrive button. In my car, the revs instantly increase almost 500rpm. My first question is, does yours do this also? My second question is WHY???

It appears that the car is changing from a locked 3rd gear (with torque converter mechanically locked via solenoids) to an unlocked 3rd gear (only using fluid to "lock" the converter). Why the car is doing this when I enable the OD, I have no idea? Can anyone explain this to me???

 

I will try it...but for more wierd happenings...check out this thread:

http://forums.maxima.org/showthread.php?threadid=32937

tell me if you experience the same.

 

In repsonse to why to your question...

maybe the tranny is building up enough line pressure so that the shift is quick...thats why the revs go up....anyone else have a theory?

 

Beats the heck outta me I always leave on O/D regaurdless of road conditions. The 3rd gen does the same thing you describe

 

Sounds like the torque converter to me?

 

Ummmmm, its not a problem. I too always shift down with OD and back on. When I turn OD back on, it still rev up. That is the torque converter.

 

I was pretty sure that this was normal and also that it's related to the torque converter. I would really like to know WHY it is doing this though. It seems that if the torque converter was already locked and you had the car floored, the converter would stay locked even if you enable the overdrive (until it shifted to 4th, I mean).

 

The same thing you describe happens if you put tranny in 2nd gear and then move it into D. Before shifting into 3rd gear, the revs will increase. I am pretty sure the same happens when going from 1st to 2nd also, though, I have not tried....

 

Usually I just leave the overdrive on all the time. But after looking at this thread I started to try turning off overdrive while at highway speeds. I kind of like it! I just turn it off get up to the speed I want and then turn it back on. Is there any disadvantage to doing this and what is the maximum speed I can turn off overdrive at?

 

Yeah, it's fun and all, but if you're worry about gas mileage...don't do it that often. Wow, 110mph. on 3rd? Highest I had 3rd on was 80mph. I don't do it often, but only when I need to, such as passing someone on the highway or racing someone.

 

Hey UMD_MaxSE, I think I have found more info for us. I discussed this problem with my local Service Mgr at Brown & Brown Nissan and he stated that both of our phenomenon sound like our torque converter locking or unlocking. He also stated that to check this, try it when your car is cold. He said that the torque converter won't mechanically lock until the car is up to temp (I'm not sure what sensor it uses to determine this). He also told me that our cars will lock in both 3rd and 4th gears, but only those gears. I tried your problem with the decrease in rpm at around 3200rpm in 3rd gear. Guess what... when my car was cold it didn't do it, but when it was warm, it did. Please try this with your car and let me know what you find. I also tried my 3rd gear overdrive scenario... also when it was cold it did not show the behavior I described above. Tells me that my Service Mgr. knows his $hit and it is our torque converter mechanically locking thereby getting rid of the slippage.

 

hmmm...thanks for the info....I will try to repeat it when cold. If it is the TC locking up, then it's no big thing....once again, thanks....

 

ok.....I tried to make the tranny do the things we had described earlier when it was cold (cold so that the TC does not lockup) and the decrease in rpm or the jump in rpm before shifting did not happen. So, it seems as if it is the TC that is doing these things.

 

it really is......

it's seems like it has a mind of it's own....

 

* X-Files theme song plays *

 

I used to do this all the time in my 1990 Camry. Then the trany blew. I lost all gears except 2nd and reverse.

Needless to say, I don't switch O/D on and off alot anymore!

TCm