G37beijing

My 2009 G37 Journey (7AT, 4 Dr, stock, 9,800 miles) did something weird and scarry last evening.

The trip between my offfice and home involves about 3/4 mile of local driving and then a highway stretch of 13 miles.The temperature was around 30F and the road surface was dry.

I started the car after work and allowed it to warm up for about a minute. When I stopped at the first traffic light (in D), I noticed excessive vibration as one would experience if the RPM was too low. Then I looked at the tach, the RPM was normal at about 650. I didn't worry much about it and drove it as usual. I didn't feel anything unusual until I was about halfway home (7 miles from start) on the highway at 70MPH. Traffic started lightening up and the speed limit is 75MPH. So I stepped on the gas slightly. To my surprise, the RPM would not go above 3,500 or so and the car started bogging really bad. I felt that the car was kind of rocking back and forth. Then I tried accelerating in DS or using the paddle shifters to down shift. The gears would change but the car was still jerking badly.

So I let off the gas and cruised at about 65MPH for half a mile or so. BTW, the car felt normal when cruising at this speed. Then I stepped on the accelerator to about halfway. I felt that the RPM initially wanted to go up but then it just couldn't overcome some resistance from the engine. If I kept the throttle position, the RPM would do this wild swing between 2500 and 3500 and shake really violently. I eventually stopped playing around with it and drove home at 60MPH.

Once I was home, I turn off the engine and let it sit for about 40 minutes. Then I took it back to the highway and none of the above could be reproduced and the car was completely back to normal. Weird, isn't it?

I'd appreciate any inputs as to what could have happened or whether any of you has had similar experiences.

Mike

iTrader: (1)

This might sound like a dumb question, but are you using 91/93 fuel?

G37beijing

I always use #97 from the same gas station. #97 RON is about the best you can get here in Beijing and is what's recommended by the manufacturer. It's equivalent to #92 AKI (US measure). It thought fuel would be one of the main suspects if the problem can be reproduced with the same tank of gas. Am I wrong?

DropTheGloves

I'd be weary of this. A member here posted about his car bogging down. Went into limp mode as he stated. I'd get this checked out asap. For all you know the engine could be getting ready to go on this car.

I have noticed from past experience with cars that a car will start to have a problem, and then maybe other times it won't happen, but in due time, it will become more and more frequent. Like I said, take it to the dealer asap, you never know man.

Nachtfalke68

Let me start by saying this...I really like this car...and I don't want anything to be wrong with it... but I just dropped my wifes 5K mile 37XS sedan off at the dealer for the 4th time after the 5th occurence that can not be duplicated by the dealer.
She was doing 55mph on the way home last nite in traffic and the car began "bucking" back and forth. No CEL's, nothing. The cars behind her had to lock em up not to smash into her because of the no brake light decelleration aspect of this. When she stepped on the gas...nothing...the car goes into Limp Mode. She had to roll across traffic to the side of the road at 20 mph , shut it off and restart/reboot. As usual...it works fine thereafter.

This issue has nothing to do with the engine getting ready to die...there is nothing wrong with it when it is working normal. If that was the case, rebooting wouldn't solve anything. This is a TCU or ECU issue, hence the repeated reboot fix. We basically demanded they replace them. I tried BB's Grounding Wires in the hope that there may be some sort of short that they might fix it , but no joy . Given the 4 to 3 downshift issues, and the general quirkiness of the 7AT...my educated guess is there is a software glitch, a Hardware problem on some, or a programming shortfall that confuses the TCU into letting the revs get too low/gear to high, and the TCU/ECU get jumbled up with the appropriate fix action (ie: kickdown to a lower gear, boost the revs, enter limp mode to protect the engine by slowing car..forcing downshift). The 3d incident was when I was driving and had my foot off the gas and the tach revved from around 1500 to 3500 5 times successively with no throttle input then went limp.

UPDATE: Dealership just called...They JUST GOT a TSB on this issue and "will have the car fixed in 2 hrs". There is apparently a ECU update that now is available to address the issue. Hopefully this fixes it! I'll try to get the TSB # when I pick it up and post again when I can.

Herkypilot

I haven't had this issue, but I'd have to agree, the 7 AT is a little quirky especially if you start pressing the gas right in between gears on a slowdown. I just got a hard bang in gear today doing that very thing. That is with the TCM update a while back. I also get rpm hangups now and again where you can let off the gas and the rpms stay up high for a couple of seconds. I feel Infiniti will have to release yet another TCM update in the near future. I hope I don't get the same engine issues, but who knows, these problems may be inter-related.

Herkypilot

G37beijing

Nachtfalke68, thanks for your input. The problem you've described is very much the same as mine. Please post the TSB number and an image of your dealer receipt after the TSB update. <!-- google_ad_section_end --><SCRIPT type=text/javascript> vbmenu_register("postmenu_2804597", true); </SCRIPT>

iiiiiekoiiiii

sounds like ur car went on safety mode, or numb mode, ecu wouldnt let u pass 3500 rpms, so u wont be able to break anything but still get to where you're going.
Its prbbly that 7at tranny, since it came out i've read nothing but bad reviews on it.
when u turn the car off it restarted the ecu. now u can rev it up and rip thru gears.

G37beijing

What I don't understand is how this "safe mode" was triggered. I don't think I did anything unusual or stupid. I'm very much convinced that there is some latent software glitch in the TCU or ECU. For some unknown reasons it happened to show up. I think this can happen to any G37 7AT as time goes by.

G35Rhino

I get this same issue as you when I press the gas while the car is decelerating with a a closed or nearly closed throttle.....like the car gets confused. In my case when this happens, the car shifts into neutral and revs all the way up for a second or two before engaging a gear with a "bang". It feels like the torque converter is locking up or something. It's definitely not right but I've had other issues with my tranny since having the flash for to address the rough downshift issue.

Nachtfalke68

Story a little different when I went to pick car up. Guess I finally threw a code, so they applied a ECM reprogram TSB from a couple months ago. Can see it here: http://rapidshare.com/files/308459740/ITB09-028.pdf . Car seems to be running well, only time will tell. It did also seem to run a little quicker than b4...so glad for that.

PeterUbers

iTrader: (1)

I just had this issue occur today -- it was 27 F outside.. does colder weather have anything to do with this?