Rev Scott

I have a 2008 5AT G37S. It's bone stock with 49K miles. When I first bought the car, I was amazed at the throttle response from a dead stop. Regardless of it being in D, DS or DS Manual, mashing the gas from the line was always quick.

A few times I have noticed that I'd hit the gas from a dead stop and the car would lag and slowly accelerate regardless of the position of the throttle. Twice this has happened, and twice I noticed that I was either just under a quarter tank of 93 octane, or the fuel light was on for being close to empty. Both times I filled tank completely and noticed the car accelerated like a rocket in comparison to before the fill up. Is this part of the ECU programming to limit throttle position when fuel is low? I haven't been able to search and find any info on this.

I also haven't found anyone else mention that when the 5AT is in DS mode (but I not manually shifted out of it), that it will hold a gear to redline, even after letting up on the gas... it will not shift normally. I'm not just talking "aggressive" here, it will stay in what is likely 2nd gear in DS and basically allow the car to slow down due to not upshifting on its own. I've seen lots of posts about the 7AT, but since there was only one model and year for the G37 5AT, there's not a lot of info out there. About 5 months ago I had the car into the Infiniti dealer (unfortunately the closest one is 1.5 hours away) and had the muffler replaced due to the TSB rattle, and they said that everything was up to date on the ECU, but who knows if they actually upgraded any software.

That's a lot of info to dump on my first post on here, but just had to get it off my chest and hope for some great info returned!

RedG37SNC

Can't say I've ever repro'ed being agressive with the throttle when low on fuel, I'm usually trying to be conservative and be sure I make it to a station at that point. I've never noticed that behavior though.

If you accelerate normally in DS mode it will shift around 4500 RPM. The mode just picks a behavior set, the accelerator really determines what RPM you shift at. Agressive pedal-redline, non-agressive-midrange. Both how much you press it and and fast you got there are monitored to determine your intent. DS mode will tend to hold gears longer but if you're not agressive with the throttle it will still upshift if you're cruising.

There's not a lot of info on the 5AT because it doesn't have the symptoms associated with ASC logic on a 7 gear transmission.

Rev Scott

Maybe I'll have to record it doing it, it's not natural shifting (it's aggressive to be sure), but it's not logical. When the display says DS, I shouldn't have to manually upshift to get out of high RPMs.

I'll make a turn, accelerate hard up to about 45mph range, and then let off the gas. It will literally hold that gear out of turn if I stop accelerating at high RPMs, not upshifting to cruise.

I wasn't worried about running out of gas, I was still about 75 miles away from empty, but sure enough it was acting sluggish off the line because of it (as it seems).

RedG37SNC

In DS mode, 1st, 2nd and 3rd no, the behavior of agressive and then holding cruise should be holding gear for about 4 seconds then up shifting. 4th it can hold for longer depending at what speed you're going. Usually when driving I leave it in DS mode and enjoy the performance, but when I get on the highway, I move it to D so I maximize high gear and prevent downshifting for the little lulls in speed. When I move to an off ramp I move to DS and watch it drop to 4th with mild engine braking.

Rev Scott

I've tried multiple times to just leave it in DS mode and drive but without fail it will hold gears even after I let off the gas and not shift. I can't put it in DS and drive it like an automatic car, I HAVE to manually shift it if I want it to upshift.

bluedevils95

iTrader: (2)

You car will act different when you under a quarter take of gas. Your car automatically goes into economy mode because your low on gas. If you like that jet start all the time keep your gas above the 1/4 and you'll be fine.

Rev Scott

Okay, that's exactly what I wanted to hear! I was worried about it the first time, then I got gas and it went away. Then it happened again and then I realized the level of fuel and decided that it must be part of the programming. I'm not sure I like that feature considering I can see the level of fuel plus have two low fuel warning pop ups when it's very low.

Unfortunately the wife is the one trying the G37 a majority of the time, so I don't have much control on the gas. I'll let her know though, it's definitely less fun to drive on a quarter tank.

I wonder if it effects the DS mode shifting at a quarter tank as well...

RedG37SNC

Hard to say, you may have a problem or it could be that you're just not familiar with the G's idea of sport and that is where it will hold gears. Several users note that difference when moving to the G... it's by design.. after all it's sport mode and that's what you want. Take a look at the G-Fun video you can see a stretch where even though I agressively accelerated I let off and it upshifted. Depends on where you are with speed/RPM, enviroment (hill/curve) and pedal. You can also see it holding gears keeping the G in the power band.

<object width="600" height="338"><param name="allowfullscreen" value="true" /><param name="allowscriptaccess" value="always" /><param name="movie" value="http://vimeo.com/moogaloop.swf?clip_id=21737766&amp;server=vimeo.co m&amp;show_title=1&amp;show_byline=0&amp;show_port rait=0&amp;color=00adef&amp;fullscreen=1&amp;autop lay=0&amp;loop=0" /><embed src="http://vimeo.com/moogaloop.swf?clip_id=21737766&amp;server=vimeo.co m&amp;show_title=1&amp;show_byline=0&amp;show_port rait=0&amp;color=00adef&amp;fullscreen=1&amp;autop lay=0&amp;loop=0" type="application/x-shockwave-flash" allowfullscreen="true" allowscriptaccess="always" width="600" height="338"></embed></object><p>Little drive showing ASC at work</p>

RedG37SNC

Interesting, never read that in the service manual. You'd think there's be a warning before testing to have the tank 1/4 or greater.

Rev Scott

I know right? Well I'll try and report back today after filling up the tank and doing some spirited driving.

KAHBOOM

iTrader: (4)

I've never heard of this before. I've never experienced this issue. Then again I drve in MM most of the time. However, at full throttle- when you press the pedal to the floor, that should override any AI setting and give you full acceleration.

KAHBOOM

iTrader: (4)

Question... What was the outside temperature when this occurred? Had you been driving aggressively before the issue occurred? Had you been driving long distance? Had you been stopped for an extended period? I ask because these cars are probe to heat soak at times. That causes the type of acceleration lag you appear to be describing.

Rev Scott

I didn't notice any problems with a 3/4th full tank. When I was experiencing the issue, it was a 50° night after about 10 min of normal driving. I had two adults in the car with me, but it wasn't "trying hard"and not providing thrust, it just was basically ignoring the fact I had floored it.

RedG37SNC

I'll have to try this.. unfortunately I get pleanty of opportunity to test empty tank syndrome...lol.