The service writer at my dealership states this is torque converter lockup. He said it happens something like between 35 and 45 mph. However, it has also happened at 52 MPH. It never happened prior to 12000 miles. The car has 13000 now and it has been happening more frequently. I think Infiniti does not yet realize that a problem is brewing.

 

It's the torque converter locking up. I've experienced this in my G35 and in a bunch of other automatics (I rent a ton of cars/trucks for work). What I've noticed is that my auto only does this within the first 5 to 10 minutes of driving which leads me to believe it is related to transmission fluid that hasn't warmed up and the higher line pressure in the tranny prior to the fluid be fully warm. High line pressure forces shifts and torque converter lockup to happen rapidly and sometimes abruptly.

 

I believe it differs from each manufacturer. I only driven the Japanese big 3 but I notice they are all different.

Toyota transmission shifts the smoothness in my opinion. Most of the time I don’t even notice it switch gears. I do notice some minimal “jerks” and “slips” between 1/4 and 1/3 throttle when switch from 2nd to 3rd gear, but it’s happen less than 1% of my driving duration.

Honda automatic transmission is the worst. It jerks every time it shifts gears, and switch back to first gear during deceleration. It's very annoying when driving in stop and go traffic. I believe Honda solves the problems on their later models with “Grade Logic” system. However I do notice a lot of transmission problems and recalls associated with this technology.

Nissan and the G behave in the middle of the two. Since my G is under 5k I can say it’s up to par with the Toyota transmission. I hope it stays the same through out the years as the Toyota did. I do notice when it’s changing gears when the rpm drops.

 

In my case, I have driven for 22 miles on I95, then get on a side street and notice it then. The car and fluid are fully warmed up and I live in So Florida so they does not take long.

 

I want my next car to be a toyota or lexus product. If this trans becomes a problem, good bye Infinti after it is fixed. I had a Maxima that had an electrical proble, an I35 that could not have the front end vibration solved and so far, the G has been great...except for these trans hiccups that appear out of nowhere and disappear just as quickly. I must get the lemon batch of nissan/infinit products. I love their styling but am tired of these problems. Toyota/Lexus, save one for me soon.

 

My girl has the same problem. I can feel it when it's going to happen. It tends to happen more in the 40-45mph range on inclines. I can avoid it by giving it more gas to change gears when I sense that it's going to skip/jump. By the way it's a 04 with only 9000 miles..

 

This transmission isn't a Nissan designed tranny. JATCO produces it for the G35/Z350/M45/FX. I have a coupe and it doesn't exhibit these problems and I haven't seen this particular problem mentioned in the coupe section. It may have something to do with the TCU since that is the only difference between the coupe and sedan tranny setup.

 

Has anybody found a fix for this problem?

 

Sorry to dig up this old thread, but my car does this to me every morning on the ride into work, and I'm sick of starting my day off this way. It always happens on the same hill when I'm holding her steady around 30-35... ARGH! It's driving me crazy. Has anyone found the problem, or is this something I'll have to live with?

 

It seems that a lot of people have experienced this same problem but nobody knows why it is happening or how to fix it???????? I am having the same problem (only I think my case is worse).
My G slips and wanders under light steady throttle around 40 and around 70. It also slips significantly every once in a while and the RPM's will increase to almost 6,000 RPM unless I give it more gas and force a clunky downshift. Even weirded... today on the freeway it seemed that the RPM's got stuck on about 3,500 RPM and even dipped down for a moment before increasing again under 1/2 throttle.
Anyone have any suggestions? I am starting to think my tranny is going bad (but it seems odd since I haven't heard of anybody else having to replace or even rebuild their tranny).

 

Have you had the car since new? If so, did you ever have the trans serviced by anyone other than you?

My point is, could anyone have added any other fluid than Matic-J?

 

I bought from the original owner about a year ago. He said he always serviced it at the dealership but it is definately possible that he could have gone somewere else.

I am going to schedule a full tranny flush for early next week and hope that it fixes my problem.

 

Good idea. The wrong fluid will have incorrect friction coefficient and cause the slip. If you caught it in time, should be no permanent damage. Give them a 4 oz. sample bottle for when they drain the fluid. Then send it in for analysis to Polaris labs http://www.polarislabs1.com/transmissions.htm or someone to determine metal content and other performance metrics for the fluid itself. May give a clue as to whats going on in there.

 

Well... I got my tranny flushed and filled 2 weeks ago at West Covina Nissan and the problem seemed to be fixed. I was super relieved and thought I had solved the problem until yesterday when it started to slip again. How could it drive fine for 2 weeks then start to slip and wander for gears all of a sudden????????????
My only thought is that maybe the fluid level is not correct or else my Transmission control unit is bad? I pulled into a gas station and checked the fluid level while the car was idling and it seemed to be way over the full line all the way to the point where the dipstick bends.
Is this how I should be checking the fluid? If anyone has any advice or knows what might be going on it would be greatly appreciated.

 

I just got a used G coupe a month ago with VDC light and slip appearing on the dash every single time. I also experience this shutter, at about 10mph, it FEELS like the speed of my car slows down dramatically like i just slapped on the brakes and it cannot grip correctly so it shutters/vibrate. I only feel it at a very low speed, about 5-15mph. I read all the comments on this thread and it seems like this is a transmission problem, at first I thought it was a braking issue but I guess not anymore since so many of you guys said it was transmission. The way I prevent this transmission problem is to start up the car, warm it up a little bit, let go of brake and dont press on gas so that the car is at a free flow speed and once my slip light and VDC light turns on then I can stomp on the gas and not worry about the dramatic jerking. For my car I VDC and slip is always on while driving, it is only off when I first start up my car and drive about a min. When it is off it worries me because when the slip light starts to blink is when I start feeling the jerkings. If anyone has the same problem as me please email me on how you solved it or we can solve it together. my email is xbarcx@hotmail.com