2002 Infiniti QX4 transmission problem

[honschoppt1]

I have an 02 QX4 with 185xxx on the clock. About a month ago I took a 3,000 mile road trip and everything seemed to work great. However, since I've been back I just started noticing that the QX4 now shifts differently. For starters it seems to be losing power uphill. When I used to be able to climb hills on the freeway at an easy 70 mph, now that is only accomplishable if I put my foot on it and rev the truck to 4,000 rpm or so. The car seems to be skipping a gear or something along those lines. It's like the powerband is now only towards the top half of 3,500-4000 rpm when going uphill. Also, when I keep my foot consistently on the gas going up a slight incline, after a while I feel the transmission sort of pulse, or something like that, until I put my foot down a tiny bit more to make it shift. It's not awful to the point where I can't drive it but I would really like to know what's going on. Any help is appreciated.

[Pathfinder2002]

Do you regular transmission maintenance? Did you change transmission oil for 60k? Also do you have a 4x4 or 2wd?
Do you have check engine light?
Sounds like your transmission is slipping. The erratic shifts and high rpms sounds like you might not be shifting into gears properly. Error codes which would show up will be P7040, P7044 and few others.

I recently had transmission issues but I got an error and I knew what to look for in repairing these issue.
Let's know if you're getting error codes and when the last time your changed your transmission oil.

[honschoppt1]

Since I have owned the car (for about 18k miles) I have not changed the transmission fluid. The truck is 4x4. No check engine lights at all the entire time I've owned it.

[yeldogt]

The transmission is slipping -- with 185k it would not be out of the ordinary to need a rebuild.

It could be the converter - but unlikely.

Did you take a look at the fluid? My guess is dark and strong odor. Take a look.

[honschoppt1]

I just checked, it was a light brown color and didn't look too dark in my opinion, and it didn't smell extra strong or anything. Would it still be a good idea to get it changed?

[Pathfinder2002]

Honestly you did very poor maintenance to your QX4 and you can try to save the transmission by doing a transmission fluid flush at Quickie lube. The transmission fluid should be changed every 60k and you're at 185k, 3x times the life span recommended transmission oil change. A rebuilt will be recommended by a mechanic. That will cost over $2500. which will not address the transaxle oil and diff oil and those should be changed as well. The differential Oil at 60k, 4x4 transaxle case oil every 60k on top of the transmission oil at 60k. Honestly the car is worth about $3000-$4000 running w/o problems. You might want to try the transmission flush and if that doesn't work, then possible selling the car and buying a new one. Unless you still want to the car rebuilding all the parts.

[yeldogt]

Was the fluid level correct?

Do you have a trusted mechanic ?

With 185k even with service the transmission would be at the ned of its life .... Very few cars auto's last much over 200k. I had a Lexus make 210k.

[honschoppt1]

I am not the original owner of the car. Like I said I've only owned the QX4 for the last year, in which time I've added 18k miles. My assumption is that the past three owners haven't completely neglected all maintenance. Based on the look of the fluid it is definitely not the original transmission fluid.

[Pathfinder2002]

I am not the original owner of the car. Like I said I've only owned the QX4 for the last year, in which time I've added 18k miles. My assumption is that the past three owners haven't completely neglected all maintenance. Based on the look of the fluid it is definitely not the original transmission fluid.

Hi Honschoppt,

I'm misunderstood I thought you had the car since 18k. Ok since you only purchased the car the last year the following maintenance needs to be done.
4x4 trans axle oil change, differential oil change and transmission oil change.
Since it seems the oil was brown and little burnt that suggest it was old.
You might need to replace the transmission since it's acting up.
Here is a video explaining transmission problems.
https://www.youtube.com/watch?v=o690DovjDAc

more than likely you'll need a new transmission or transmission rebuild. Anycase it's very expensive about $2500. Plus the other oil should be changed as well with the transmission issue.
Good luck on getting your car fix.

[yeldogt]

Changing the fluid is not going to fix a slipping transmission. In rare .. extremely rare ... it may solve some harsh shifting issues. For the fluid to cause problems ... it need to be contaminated. Trans fluid is not subjected to the products of combustion -- H2O is a big oil killer.

[attofarad]

Your fluid shouldn't be light brown. It should be pink, or at least sorta pink. Long time since it has been changed, maybe never. My wife's was a bit like that, the first time I changed it.

I agree that significant slipping isn't likely to be helped by changing the transmission fluid, but it is relatively cheap to try.

I use the Castrol Multi-vehicle Import fluid. http://www.autozone.com/motor-oil-and-t ... ckfit=true

I suggest not bothering to drop the pan. Check the level when properly warm and running, drain the fluid out, measure it and put the same amount of new fluid back in. Drive it around a few minutes, and do a second drain/fill. See how it goes.

Not sure whether it applied to the 2002, but the 2001 had a service bulletin to replace the transmission controller (box mounted under dash near hood release) and the solenoid pack (inside transmission) if slipping occurred. The problem was slipping when cool, but not cold or warm. It would be obvious, as the engine would rev up while the speed wasn't much changing. My buddy had a 2001 Pathfinder that did that, but still lasted the 265k miles he had it. My wife's QX4 did that -- I replaced the controller with a part from a wreck, maybe $60 if I recall. and that firmed up the 1-2 shift. Still would slip sometimes from 2-3, typically when ambient temperature was about 50F and she had driven about 1 mile, and trying to accelerate uphill onto the freeway. I told her that I would replace the solenoid pack if she would pay for the part, at $300 or so, but she opted not to. Still working fine at 208k miles, occasional slip under just the right (wrong) conditions.

I don't have any experience with such, but you could consider sending in a sample for used oil analysis. All wear components will likely be high, but it would tell you the percent water, in case you have that type of contamination.

Here is a transmission fluid change write-up: http://www.nicoclub.com/archives/how-to ... r-qx4.html