Had my auto tranny rebuilt on my 90 GXE about 3 months ago. About a week after I got it back, I took it back to them because the car seems to "hunt" for gear when it gets to about 45 mph. They put some additive in it (red line, I think) and I went on my way. Didn't totally fix it, and it's getting to be a pain.

If I hold it right at 45, it will shift back and forth right around 2K rpms. Won't pick a gear until I either accelerate through 45, or slow down. Doesn't slip at all, just that little lurch shifting back and forth.

Question is, is that caused by some electrical problem, like with the tranny control unit, or is it something mechanical that they need to fix. Any thoughts?

 

bump....any help here? Anyone ever had this prob before??

 

I don't drive 45! 55-80 sure! but not 45

 

WTF?! I swear I replied to this earlier...

1. check tranny fluid. they tend to hunt and downshift really easy if the fluid is low.
2. make sure all sensors are connected. could be a tranny issue, could be a MAF or TPS issue. TPS is very likely cause if the tranny won't kickdown when you floor it, but yours is almost the opposite. could be the TPS is going the wrong way too though (but strange it would do that)

anyway, there's about a zillion things it could be.
toqrue convertor locking up properly?


the tranny shop should be able to plug it into a computer and play with it to see what's going on.

 

I knew I was asking for it with my "driving 45" comment...
Anyway, thanks Matt, for the suggestions. Fluid is fine, no problem there. Could be TPS...I'll have to drive it like internetautomar suggests and see if it will kick down properly.

Funny thing is that other than some broken exhaust studs, the car runs great at all other speeds, and no tranny issues other than right between 45-55...if the TPS was going out, wouldn't I have issues at other times? Even at idle?

 

Easy solution:
don't drive 45-55

 

internetautomar, you are so funny! (hey doc, it hurts when I do this....)

Unfortunately, the main road to my house is a 45 limit, and there's always cops around...surely you're not saying drive BELOW the spped limit, are you

 

Paint your car grey it'll blend in with the street.
and absorb the radar guns rays

 

The company I work for makes radar guns....I don't think that would work...

 

Sure it can With right grey paint

 

If you frequently drive with the Overdrive on... Like I used to when I experienced this problem a lot with my Max...

Try taking the car out of Overdrive if you are driving under 55-60mph.

Only keep the Overdrive on when you are driving 55+ for more than I'd say five minutes contiguously.

You should notice it having the shifting problem less.... Let me know, cause this seemed to help mine tremendously.

 

all you're doing is removing the gear that it's jumping between the problem still exists.
your car is DESIGNED to go into 4th (OD) at 45 mph under light to moderate throttle.
AND the trans is electronically controlled
Hence the presumption that it is probably a TPS going bad

and remember:
Next time you cut off your finger. Just put a bandaid on it you won't notice it then

 

When my car does it, it's usually between 2nd and 3rd...

And this was what I was told by a Nissan dealer, a mechanic, and a good friend who worked for Nissan for 8+ years. It's also in my Owner's Manual....

Don't believe me? Fine, but it was just a suggestion.

It doesn't only take away a gear, but when you're in OD, the car is programmed to shift differently.

Seems to have fixed my car's jumpyness.

 

I appreciate all the suggestions, as usual. In city driving, I am all over the speed range pretty much constantly, so I don't think I would want to keep switching in and out of overdrive. (did that when my tranny was going out, and it helped some for a while). Now that it's been rebuilt, I just want it to run like it's supposed to after $1800 worth of work. I'm still inclined to think it's electrical-related, since it otherwise shifts fine, and it IS electronically controlled. That's why I was asking in the first place, so I don't go rip the tranny shop guy a new one when it is an electrical problem, not a mechanical-type tranny problem. Seems like they still ought to be able to diagnose that, though.

 

I had mine rebuilt too and it seemed to fix it for a while, but I agree, it has to be something electronic.

When mine jumps, it seems to activate the switch for "Power" shifting (I don't know if the other models have this) and the light blinks on and off a couple times. Does this happen to yours too???

 

Hmm...can't say that I've looked at that. I'm usually looking at the RPMs and MPH to see where it's shifting at. I'll check that out and let you know. If it's flashing, it could be error codes. You might want to count the long and short flashes next time. There's a tranny diagnostic procedure posted somewhere that might be helpful.