I will start by saying that I have done some searching on both MyG37 and google for previous threads about this issue and couldn't really come up with anything. If I missed a specific thread about this issue it wasn't for lack of searching. Also, I am aware of the software issues with the transmission and the latest version was installed by the dealer about a month ago.

I have a 2010 37s with the 7at. I got it used last November with approximately 45k on the odometer.

The problem consists of abnormal shifting between only 3rd and 4th gears. When accelerating between 3rd and 4th the transmission will slip with a noticeable jerk about half way between gears, then it will continue accelerating in 3rd gear until shifting into 4th with another slip and noticeable jerk. The problem is worse when the transmission is cold, and it gets progressively less noticeable as the car warms up.

I have been to the dealer twice about this issue. The first time the tech "could not replicate" the problem and went ahead and updated the transmission software. The second time the tech said that he may have slightly noticed it; he said that the transmission was 0.5 qts low and that it shifted fine after he topped it off.

To no avail the transmission is still shifting exactly the same after both trips to the dealer. I am getting ready to take it back and request that I go for a ride with the tech. However, this time I wanted to ask everyone on the forum and see if anyone else has experienced this issue with the 7at. Any advice or help would be greatly appreciated.

 

This has been covered many times over on this forum actually, and it really is related to how the computer tells the transmission to shift. It's all in the way the torque converter unlocks and locks...Nissan/Infiniti actually bragged about how the torque converter can partially lock in this 7-speed JATCO transmission.

Mine does it every now and then as well. You can tell the torque converter is varying its lockup in the midst of this odd gear change when you increase the throttle and the revs really flare.

 

So this is a software issue? I'm taking mine in on Weds for some warranty issues and this is one of the problems.

 

I'm out of warranty, will Infiniti do a software update for free or are they going to charge $110 or whatever they charge these days?

 

The software updates has improved the shift logic but the flare seems to still remain. You can rest easy knowing its not harmful...its just annoying.

Your dealer probably will charge you for the software update if you're out of warranty unless you have a good relationship with them.

 

Your tranny is slipping on 3rd and 4th sounds like a tranny issue more than a software issue. When was the last time you had the tranny serviced? I hope I'm wrong but that sounds like it needs to be opened up or replaced. Good luck.

 

You could be right, but from what I have read most people are seeing a modest to a sometimes drastic improvement in transmission behavior after the update. After they updated my I saw no improvement in this particular issue. However, I did notice that the other 6 gears seemed to shift a little quicker and smoother.

This problem doesn't happen to my G every now and then, it happens every time I drive it after it has had time to cool off.




I am no expert mechanic by any means, but it really feels like a mechanical issue not a software issue. The problem happening only between 3rd and 4th seems to specific to be an overall software problem.

From what I have read online these transmissions don't have service intervals, they are supposed to "last the life of the car."

 

Reset ECU. Clean throttle bodies. You'd be surprised at the results.

 

No such animal as lasting a lifetime even the BMW that suppose to have a sealed tranny fails after 50k or so. Tranny needs to be serviced every now and then it just varies from manufacturer. I learned my leason on that with my other car. I get mine service every 15k regardless if the car needs it or not. The money I spend on doing this is far less than having to replace the whole tranny or getting the damn thing overhauled. But then again that's just me..

 

I actually had this done 2 weeks ago. It is really amazing how much it smoothed the whole car out.

2009 W/ 57K miles and all the damn 7AT TSB's

 

Well, it turns out that I wasn't crazy and my problem was not software related. After getting a video of my tachometer slipping and showing it to the service manager it appears that they took my complaints seriously. Within a couple of hours they were able to replicate the problem, crack the transmission open, and get the ok from Infiniti for a complete transmission replacement. Apparently the solenoids were stuck in the lower and mid gears. The service rep said that it should be ready to pick up next wednesday.

On another note, at least I get to really test out this Q50 loaner for about a week.

 

That's an unusual failure -- wonder if it was related to the loss of fluid, which would have resulted in greater heat when shifting and could have damaged the solenoids.

Did they find any evidence of leaks? Also, were you the original owner?

 

can you post up the video?

 

The service rep said that they didn't see any sign of leaks, also, I got under the car and did a visual inspection and didn't see any leaks either. I was pretty curious too as to how the fluid might get low on a sealed transmission with no service interval.

I was not the original owner, I got it with approximately 45,000 on the odometer. The only thing I could think was that the original owner got the fluid changed by an independent mechanic who didn't fill it up all the way and/or put in the wrong fluid.

I am glad I got this figured out, it was driving me nuts.

 

Yeah, let me get it on youtube and I will post the link soon.