---Hesitation at ~40mph--- Input Request!

[SteveTheTech]

Ok guys the time has yet again come to help me try to help you guys.

Here is the situation that some of you maybe experiecing;

Your driving down the road (>40mph) the RPMs will drop and the car is in "overdrive" at this point. When you go to pass someone of accelerate you have to step into the throttle a little to accelerate, but nothing happens except for the transmission feeling like it is lagging. After pushing the accelerator sensor more it finally overcomes full lockup and drops down a gear or two (depending on throttle sensor input) and you rocket away.

There are many ways to describe this concern, from a hesitation to a dragging, but if the symptoms closely resemble something you are experiencing please check the survey and or leave a quick note about it.

The goal of this thread is illustrate to the company that people are experiencing this concern and that there is indeed an issue. The good news is this is not a component failure, or at least to the best of my knowledge it seems like a software glitch in the transmission control computer. At this point there is no resolution for it except to try to relearn your shift adaptives but that does not work for all the people who are experiencing this concern. So what I want to do is get some input from you all and ideally I would like to pass this on the my friends in the company to see if we can get the first NICO inspired TCM reflash.

Note; All I am looking for is your experiences with this issue anything that is not constructive to the topics purpose will be either removed or moved to another thread. Lets give them a shining example of what Nico can do

Thank you guys in advance for your help, I know you won't let your fellow EX owners down.

[kullenberg]

No no hesitation, either in normal D, or in DS. Steve: I tried to add another cat. for just plain NO, but all I got was a blank page? I tried it today in all modes, up hill, down, and level. No problem I thought that was a fuel pump issue.

[SteveTheTech]

Pat,

I'm glad to hear that you do not have this issue.

This issue has nothing to do with the fuel pump.

I too tried to add another category but it told me I could not vote more than once, even though I had not voted at all.... I'll see what I can find out.

If any of you guys have any experience you would like to share, please feel free to share your story.

[rontek]

It is AMAZING to me that you EXACTlY described one of my biggest problems and "pet peeves" with the EX. When I first purchased the car I thought for sure it had to be something wrong with my vehicle. But after taking out two different loaner EX's from the dealer, I found they all had the same "issue". I was also amazed how completly different the AWD G35 and G37 loaners I drove shifted, compared to the EX. It actually bugs me so much sometimes that I was thinking of asking my dealer to reset the ECU so I could go through the "learning" phase all over again. I am VERY pleased that it is a recognized defeciency , and that there "may" be hope to get it corrected. If there is anything I can do or input I can provide, PLEASE let me know.

Thank you Steve !

Ron

[dividedhighw]

+1000 ... I simply couldn't have said it better than Ron -- MANY thanks, Ron!!

Seeing how two EX forum members have recently abandoned their EX for an FX, I was starting to wonder if I would have to do likewise (or maybe give up on Infiniti altogether) ... not because of the lack of rear seat room, but this problem. This little nugget nearly got me in an accident the other day, first because of the hesitation, but then the ridiculous over-acceleration thereafter!!! When I got home, I told my wife, if I die in a car crash, figure out if this was the circumstance and if so, SUE INFINITI FOR EVERYTHING THEY'VE GOT!!! (Yes, I was absolutely incredulous!)

Steve, if you can get Infiniti to address this issue on our behalf, I would be ETERNALLY grateful!!!!

Cheers,David

[AWGD8]

HONESTLY, I would never trust a D drive in sudden acceleration or

passing. Not unless it`s a torque monster car like the V8`s.

When I had my V6 Rav4, It did the same thing, 2 secs delay before the

transmission downshifted. Good thing the Rav4 has 4 drive (4th gear) next to D,

So I could downshift the gear manually for passing. With our EX35 theres

no way you can 100% drive in D! there is so much hesitation (feels like a

clutch is slipping). I guess that makes the car feel smoother and less jerky

like the G35/37 sedan. I`m sure it does need a TCM reflash.

To solve this problem use the Manual mode (not the DS mode).

[googleman]

I haven't noticed this as I immediately shift to the DS mode when I need fast acceleration. Will try this on the highway next time. I hope it is not as bad or difficult to fix as 2007 BMW X3 transmission hesitation problem.

[AWGD8]

From my experience, that hesitation seems to be consistent on 2nd gear to 3rd gear around 30-45 MPH. It`s like clutch slipping....

[RioD007]

This is why i ALWAYS use manual mode

[sxgt]

This happens to me very frequently. Between 3k -4k RPM < 45 MPH - always in D. If I put in DS - I haven't expd it. I probably should unplug the battery and let the computer relearn my driving style. I am mostly laid back so it might have learned that.

[rontek]

I do not believe just disconnecting the battery will do the trick. I am "pretty" sure it needs an ECU re-set with an Infiniti Advanced Diagnostic tool.

Ron

[cjre1]

Two days, I replied by voting about my car that it hesitates. Today when I brought my car into the shop, I told the dealer this and he says that he can fix this. It is a computer software update to the ECU. He fixed this 5 hours ago and test drove it. No more issue.

[AWGD8]

cjre1:

You mean update = reset using the computer tool?

[cjre1]

AWGD8,

Not sure. I am sorry, I didnt ask him about using the computer tool. I can ask when I pick up the car next week.

He told me that they had to flash the ECU and update other software to the current release, whatever that means with or without the computer tool.

Can you please tell me what si the computer tool?

Thanks.

[rontek]

Steve,

Can you jump in here before this gets more confusing? Is there any new ECU software version, or any EX35 update released recently?

Two days, I replied by voting about my car that it hesitates. Today when I brought my car into the shop, I told the dealer this and he says that he can fix this. It is a computer software update to the ECU. He fixed this 5 hours ago and test drove it. No more issue.

[cjre1]

Steve sure will help out with this. I only know what the service manager told me. This dealer, I believe 100%. I even read on his computer screen this morning that the new update fixes, hesitation, idle lag, timing adjustments and emission control sending to the computer. There were more on there, but he flip the page on the screen.

He also told me, that he is under strict guidelines to only update cars software if three or more items are persent per findings. This was stated on the compuer screen. I read it.

[SteveTheTech]

Right now there is not a fix as far as I am able to tell. Only three days ago I learned that other people are experiencing this and I thought it was a by-product of adaptive shift logic coupled with a light foot and traffic to have a set of shift points leaning more towards economy over performance, and was more a result of the continuous traffic in the DC area.

I know that about two weeks ago I had a car that had been in for this concern and after resetting the base parameters (ECM short term learning is the closest to transmission adaptives we can reset). As of this morning there were no new or old bulletins that specifically referencing this concern in the EX, there is something similar on the 06 G35x. The software is indeed able to be reprogrammed so this should be fairly easy to get resolved although we need to draw some attention to this before we can try to get the wheels moving.

[SteveTheTech]

Steve,

Can you jump in here before this gets more confusing? Is there any new ECU software version, or any EX35 update released recently?

You know I cannot say that there are NO updates available. The way they are fixing electrical component issues now has caught up with the technology common in a Flat Screen TV, or Adobe Reader software, so I am sure there are reflashes for certain compaints. This is a simple update in pre-programmed tolerances and adjusting some parameters. They have had these types of updates for about a decade now. What I am talking about is there is nothing currently addressing this issue.

[sg77]

cjre1, I think AWGD8's question was whether they just reset the adaptive shift control (to make it re-adjust the shifting based on your driving style), vs updating the software to a newer version. If you actually saw the screen describing the update though, it sounds like it wasn't just resetting the adaptive shift.

I'm not sure if I've seen the same problem you guys are talking about, but what I notice, even at higher speeds like 65 mph, is that when I floor the gas pedal, the RPM goes up immediately but there's a 1 second delay before the car accelerates.

[rontek]

You know I cannot say that there are NO updates available. The way they are fixing electrical component issues now has caught up with the technology common in a Flat Screen TV, or Adobe Reader software, so I am sure there are reflashes for certain compaints. This is a simple update in pre-programmed tolerances and adjusting some parameters. They have had these types of updates for about a decade now. What I am talking about is there is nothing currently addressing this issue.

But is there not some sort of reference available to you, that lists the latest ECU software versions and if there are specific updates for specific vehicles?

[Ogiku]

thank good , other people have the same issue. I had my computer reset but after a short while i had the same lack of power up to 80km/h and then almost stupid boost of power.Like you'r in a Jet waiting to take off.

What i also expierience is when i take gas 91oct from Esso it gets whorse but when i switch to Shell 91oct or Sunoco 94oct it is way better almost not to feel.

[cjre1]

Sounds like the gas has a lot to do with your problem. This problem is present, but I take it that it depends on where you buy your gas also matters. I wonder if thishas something to do with the PMFI.

Central to an EFI system is a computer called the Engine Control Unit (ECU), which monitors engine operating parameters via various sensors. The ECU interprets these parameters in order to calculate the appropriate amount of fuel to be injected, among other tasks, and controls engine operation by manipulating fuel and/or air flow as well as other variables. The optimum amount of injected fuel depends on conditions such as engine and ambient temperatures, engine speed and workload, and exhaust gas composition.

[SteveTheTech]

But is there not some sort of reference available to you, that lists the latest ECU software versions and if there are specific updates for specific vehicles?

There is, and when I checked yesterday morning there was nothing for the EX. I'll screenshot it when I get in tomorrow.

cjre1, I think AWGD8's question was whether they just reset the adaptive shift control (to make it re-adjust the shifting based on your driving style), vs updating the software to a newer version. If you actually saw the screen describing the update though, it sounds like it wasn't just resetting the adaptive shift.

I'm not sure if I've seen the same problem you guys are talking about, but what I notice, even at higher speeds like 65 mph, is that when I floor the gas pedal, the RPM goes up immediately but there's a 1 second delay before the car accelerates.

When the software is updated all variable and short term learning are erased. As a short answer the ECUs do not need to be reset to alter your learned positions and attributes. You need to change your driving style. Since not all EX drivers are experiencing this issue I think this is a driving adaptive glitch, in the transmission computer and little else has anything to do with it. Since the TCM (inside the transmission valve body) controls shift points and TCC duty cycle when throttle input is received the transmission should almost immediately shift to the range needed to provide adequate torque when demanded. The issue some here are experiencing seems to be a flaw in the logic where more than 2 of 8 steps (translated APP value sent to the transmission) is required to overcome full TCC duty cycle. Altering this is a mere matter of re writing some software.

The issue you are experiencing with a WOT delay may be something else. I highly suspect this is a momentary delay programmed into the software to prevent high torque damage to the transmission and transfer case. I have experienced this and I think that it wants to also ensure that you are not just stepping into for a brief second, as a way of trying to ensure comfortable ride quality.

[googleman]

Does the computer learn in the DS mode by any chance? I do all my aggressive driving in DS, and shift back to D when I calm down If the computer is learning only in D, that is quite bad for me.

[aft981]

Yes, as I mentioned under another topic, this does happen to me, not every day though. Only around 40mph +-3mph and when cruising along at a steady speed, then when i try and accelerate, whether quickly or slowly (even if I just want to get up to 45 or 50) there will be a moment of hesitation, the power seems to disappear, almost as if it's about to stall, but just for a split second, and then all is fine again. I mentioned it to the dealer the other week, they couldn't replicate the issue, they recommended an induction and intake service, which I had done (and thanks Steve, I probably won't bother with again!).

I think some people are possibly mistaking this issue for something else. The one I'm talking about (and I think the one Steve is talking about) doesn't happen at higher speeds, doesn't happen at higher revs (someone mentioned 3-4k) and doesn't happen in lower gears. To me, it's when the car is barely ticking over at 40mph, the revs only just over 1k, presumably in 5th gear at this point (whenever you are driving in manual mode, it will JUST let you shift into 5th at 40mph+). As Steve mentioned, I have a feeling it probably is just a software glitch.

Coming from the UK, where 90% of cars are manual, most of my prior vehicles have been manual transmission, and it feels the same as if you are driving a 1.4L Focus, trundling along on a road where the speed limit is 30, and you can just about put it in 5th gear (to get that mpg right up) without it stalling, but then the speed limit ups to 40, you put your foot down a little, but the car just doesn't have the power to accelerate you from 30mph in 5th gear, and it will hesitate and struggle, verging on stalling. Obviously as an intelligent driver, you know to shift down to 4th or even 3rd before you start trying to pull away, and I think that is what seems to be the problem with the EX when you're at 40. I think it tries to pull you away in 5th gear, struggles, and then shifts down. It needs to shift down straight away. I could be wrong. Steve?!

[rontek]

There is, and when I checked yesterday morning there was nothing for the EX. I'll screenshot it when I get in tomorrow.

Thanks Steve, Thats what I figured.

[zozoka1212]

Does this happen with both RWD and AWD? How about VDC off and on? Just a thought.
Modified by zozoka1212 at 7:28 PM 6/7/2009

[AWGD8]

I have an AWD and yes hesitation happens either vdc on or off on D.

[Bmore]

I have a hesitation issue, though I haven't tracked when it occurs. I just know that when I first bought the car, it was very noticeable to me that on the highway when hitting the gas there was what felt like a huge delay before the acceleration kicked in and then, when it was ready, the car shot off like a rocket with lots of power. I thought it was just the car, but I always notice it because it has never happened on another car.

[cjre1]

I have a hesitation issue, though I haven't tracked when it occurs. I just know that when I first bought the car, it was very noticeable to me that on the highway when hitting the gas there was what felt like a huge delay before the acceleration kicked in and then, when it was ready, the car shot off like a rocket with lots of power. I thought it was just the car, but I always notice it because it has never happened on another car.

Do you have a new fuel pump? If so, when was it installed?

Just got off the phone with Infiniti tech at head quarters and he told me not only where the pumps were recalled for the humming noise at start up for 1-3 seconds, but it also causing the car to hesitate at different MPH. Good to know, since no where on any thread this is mentioned.