Throttle / Shift Lag after TCM flash?

[ozzypriest]

Originally Posted by G35Rhino

I don't buy it....I could be wrong but I just don't believe Infiniti would put you in a 328 hp car, let you think you have the power to pull out at speed in a high-traffic / high-speed situation and then leave you sitting there to get run over when the car hesitates.

Well, there's the big question - did they or didn't they? In my limited experience with high-performace sedans as of late, they probably did limit throttle's behavior, it's probably situational - that is, dependent upon yaw readings, speed, previous throttle opening readings, rpms, and other ecu/tcu parameters. It also seems like the Asian and European makers are much more likely to nanny the driver than say, Ford or Mopar or even GM. I'm not trying to be anti-anything, I'm just saying that simply seems to be the case.

Regardless, I sure wish there was something I could do about it's lack of responsiveness, the torque management, and the shift points. But I haven't yet read the thread I was directed to a couple of posts back....

[ozzypriest]

Originally Posted by KLB

Read this thread

I did read this thread. I posted in this thread - it's all about ECU stuff and Cobb, and doesn't address any efforts to alter the functionality of the transmission. Personally, I think the engine is pretty good as is, and it's the 7AT transmission that is sorely lacking in its ability to deliver the performance goods. DS is geared for driving on the track or on curvey roads, and not at all for straightline performance. I realize that many G37 owners seem not to care about straightline performance, but I do and I want my car to deliver the goods that I know it has....I am not seeing anything near the straighline numbers the car rags report - C/D with 5.0 0-60 in an AT? Not in my numnerous attempts - nowhere near....

[Herkypilot]

G37Rhino,

I'm getting about the same MPG's as before the TSB mod. I feel that the situation is 90% improved over stock. Much improved ride now. I have to admit, I haven't been doing the coasting/flooring test so I can't provide input on that part of it.


Herkypilot

[G35Rhino]

Originally Posted by Herkypilot

G37Rhino,

I'm getting about the same MPG's as before the TSB mod. I feel that the situation is 90% improved over stock. Much improved ride now. I have to admit, I haven't been doing the coasting/flooring test so I can't provide input on that part of it.


Herkypilot

Thanks for the feedback...glad it is working out for you.

Overall I am happy with the results of the flash (the mpg is minor and may be unrelated). Guess I'll just have ease into the gas rather than flooring it. Seems to work well that way.

[G37Obsidian]

I posted in the other thread, but I am noticing throttle lag since the flash. I'm 99% sure it wasn't there before the flash. It's almost like they reprogrammed the tranny to be in a higher gear all the time. It's frustrating because if you are moving and floor it, even on the highway, there is about a 2 second lag before it kicks in. I wonder if we can reverse the flash and go back to how it was?

[Herkypilot]

Here's my recommendation for all those who have the 2 sec throttle lag when you hit the gas...I try to anticipate that I want to accelerate quickly so I'll bump the shifter into DS and it usually downshifts one or two gears - then when you hit it, there doesn't seem to be any lag when the RPM's are higher. The tranny appears to be seamless when I do it that way.

I like the shift pattern for stop-n-go traffic alot better now as it's not constantly trying to run through the gears as quickly as possible to get to 7th and lug around at 40 mph! I wouldn't go back to pre-flash if given the option.

Herkypilot

[G37Obsidian]

I find that there's even a lag in DS mode, albeit not as bad as D. And manual mode is horrible, it takes forever for it to shift when you bump it to the next gear

[dbg37]

I have not experienced any throttle lag that I can remember, but I will mention a couple of variables that you may not be considering.

1. Under lower speed coasting situations the torque converter may be locked, this is to provide both maximum MPG and also to achieve engine braking when the throttle is such that it no longer is providing pressure against the drive train. When the throttle is suddenly depressed during these modest speeds, the torque converter must unlock so that the engine torque can be multiplied & taken advantage of, otherwise the engine is bogged down.
* this issue is probably also connected with the rpm "flare" that some people are complaining about. The converter unlocks, the shift occurs and the it re-locks and does it slowly enough to give noticeable rpm climb before it re-engages. I believe this is intentional to keep the shift from being hammer like. Fluid under pressure can absorb shocks where a locked tranny is direct pressure against the gears.

2. Under some circumstances the VDC nanny may be limiting power application to prevent sudden wheel spin. They probably built in a delay to allow the torque transfer to the pavement before hammering home all the engine power.

I suggest you try and mimic the conditions under which these events occur and do it in DS mode with the VDC turned off. Be CAREFUL though because at some point things will get squirrely.

DS mode should limit early converter lock up and demand higher shift points, and the VDC off gives immediate power application without consideration to wheelspin.

I know that there is a substantial driving character change with the VDC disabled. It is like mild mannered Clark Kent took off his glasses and unbuttoned his shirt.
The G37 has a dual personality for sure.

[Mockenrue]

Originally Posted by dbg37

2. Under some circumstances the VDC nanny may be limiting power application to prevent sudden wheel spin. They probably built in a delay to allow the torque transfer to the pavement before hammering home all the engine power.

I suggest you try and mimic the conditions under which these events occur and do it in DS mode with the VDC turned off. Be CAREFUL though because at some point things will get squirrely.

DS mode should limit early converter lock up and demand higher shift points, and the VDC off gives immediate power application without consideration to wheelspin.

I know that there is a substantial driving character change with the VDC disabled. It is like mild mannered Clark Kent took off his glasses and unbuttoned his shirt.

You are definitely on to something. I turned off VDC and the throttle lag was basically gone. Much different experience (even in regular D mode). Though I didn't get out on the highway, it was much more responsive and didn't give you that "spool up" feeling. Only downside is that you have to remember to push the button each time since it's technically a safety feature.

[hadokenuh]

So please educate me: It should be relative safe to turn off VDC in dry weather and floor it all the way? Is there anything specific I need to look out? Tire conditions?

Thanks guys! I learn new things everyday.

[G37Obsidian]

I'm also wondering if the ECU will "relearn" after the update and eventually act like it was before as far as throttle lag, etc. Does anyone know if that's a possibility? Could the throttle lag improve after a couple thousand miles of driving?

thanks

[G35Rhino]

After some more time behind the wheel the issue is definitely not related to throttle lag, it is definitely a tranny shift issue. "D" seems to be getting worse and worse. I'd be amazed if my 0 - 60 time was <6.5 seconds from a rolling start....and the problem is only worse at higher speeds. The car simply does not want to downshift. I hit the gas and wait while the dull growl gradually gets louder and then wham it shifts down a couple of gears or more and the rpm's crank up to 5000 and it's off to the races.

Someone mentioned the possibility of this being a safety feature....if so it's going to be one of those features that gets someone killed. I'm not talking running around a track or auto-x I'm talking around town and highway driving. Something is not right and I am finally starting to hear from other folks who have the same issues.

[Mike P]

How do you drive? Of course there is throttle lag when you punch it. This is fly-by-wire system. The computer will always do that in "D" since it is trying to get fuel economy. You are also in the low end of the power band of the gear. Try driving in "DS". The car will be much more responsive. Although I believe it is a safety issue, I think the issue is with the driving and not the car and how the car operates. You can also shift the gears yourself in any model of this car. If you don't like the auto, then shift it yourself. I think the auto is good for driving around town. If I am going to hall *** then I am in "DS" and I am using the paddles.

[G35Rhino]

Mike thanks for the response...but I have had other fly-by-wires and never these issues. Also, I have had the car since January and didn't have any complaints other than the occassional flare at 40 mph when it was cold and the annoying 20 mph rough downshift/engine break. My complaints about the tranny (or its programming) came after the flash. I'm not saying everyone has the problems I am having but there are some...and I'm not crazy.

The problems are in D and DS (although not as bad as D). No lag with the paddles but if I wanted to shift all the time I'd have gotten the manual tranny. Both my TL and first G had manual tranny's and I was ready for a break.

[saltfish]

I know i said that its probably a safety feature however i believe the throttle delay can and should be shorter.

I also don't like when the car makes that dull growl when flooring it which is why majority of the time i'm using the stick or pedal shifters.