Sluggish automatic overdrive

[SHB001]

Hi, I purchased an EX35 about a month ago and noticed a sudden change in the way it was driving after 200 miles. At speeds around 30-40 mph in automatic, car becomes sluggish and slightly vibrates. Switching to sports mode rectifies the problem since transmission immediately shifts down. Dealer tells me it is the overdrive that's kicking in and it is intended to save gas. I don't want to save gas (at least not right away with cheap gas prices) at the cost of sluggish high overdrive gear, and contrary to dealer recommendation, I can't slam the gas pedal in traffic to force the car to shift down. I am now at the point of just driving in sports mode so not to induce this condition. Dealer also tells me it is an acquired behavior, so they went ahead and reset car's memory, in effect trying to wipe clean its memory of my driving behavior. It did nothing. Fresh back from dealer and there it is 30 minutes later and even a bit worse. Now it enters this mode at about 25 mph. I know my other car, a 328 bimmer is supposed to learn from ones driving and adjust, but didn't know about the EX. Didn't see anything in that regard in the manual, but may be it is true. In any case, with its memory wiped clean, the problem stays. I am trying to see if I can download bimmer's memory into the EX since that car drives just fine. Has anyone else noticed this behavior and is this normal overdrive operation? Any recommendations?

[dividedhighw]

Welcome to NICO, SHB001!

If I can clarify the symptoms you're reporting, is the vibration occurring because the car is running at too low an RPM - leading to engine "lugging" and hence, vibration? If so, you definitely have a problem that should be corrected. Perhaps one or more sensors is faulty, feeding erroneous information to the engine management electronics, so it's upshifting or locking "overdrive" way too soon.

Yes, the EX's transmission is supposed to be adaptive (i.e. programmed to modify shift points & responsiveness based on the way you drive), but don't expect it to do so perfectly - it doesn't.

I've read that Infiniti purposely made the EX's throttle less responsive (compared to the "G", for example) after initial field trials because some testers thought it too twitchy ... this was done to make it seem more refined, thereby enhancing the impression of "luxury" over "sport".

I wouldn't say I have a heavy foot, but I do expect the car to be responsive when demanded, so on that point, the EX has failed to deliver. Now approaching 11,000 km (about 6500 mi) on the clock, mine is just starting to be tolerable in "D". Perhaps given much more time, yours will begin to adapt appropriately to your expectations.

In terms of "downloading" your BMW's learned behaviour to your EX, I would be shocked if that was even possible. These types of parameters (and the way they're saved) are completely vehicle-specific, but hey - one can hope, right?!

Cheers,David

[302@12psi]

While my car was in the shop I had a G35 loaner.

The throttle delay was awful. You'd hit the gas and could notice a delay. My EX doesnt have this issues.

The gearing was bad on the highway. At 75-80 I was pushing over 3k rpms....my EX doesnt have this issues.

My EX does dump into OD every once in a blue moon when I'm climbing a hill half way up. It's nothing "bad" as long as I maintain the throttle the way it is. If I tip the throttle just a bit it's downshifting which can become a pain.

I'd assume if your OD is kicking in at those speeds on a warmed up car something is wrong. HOWEVER I'd continue to drive it a bit (maybe a bit agressively) since the ECU was just reset. Hopefully it'll learn your driving habbits.

I was not overly impressed with the DS or the Manual Shift mode in the EX.

[dividedhighw]

While my car was in the shop I had a G35 loaner.

The throttle delay was awful. You'd hit the gas and could notice a delay.

I'd hazard a guess that your G loaner was in desperate need of servicing. I had the opposite experience, having had two different G's as loaners, where both were much more responsive to throttle input than my EX. In addition, neither exhibited the odd (and annoying) behaviour of my EX ... half the time it kicks down a gear, a huge roar is heard, but not much acceleration accompanies the noise.

Cheers,David

[SHB001]

I second that. I got a G35 as a loaner and found it much more responsive and did not notice any of this overdrive struggling and vibration that I notice in the EX. And the G had 25K miles on it too. Although it wasn't an AWD.

[302@12psi]

My loaner had 25k on it.

Maybe I'm spoiled or do not drive my EX hard enough...other then a few times I havent noticed it being in what I thought was the wrong gear. If I need more it downshifts smoothly and begins to ramp up very nicely in the powerband.

[exfanNY76]

I've not seen this issue occur in our EX. We only have ~350 miles on the car, and the car has plenty to give when required. I've not once needed to really floor it. With 297 HP to play with, it doesn't take much to get the car up to the speed limit and beyond. Plain and simple, when I ask it to move, it moves!!

[AWGD8]

Honestly, I hardly use D during my 20mins commute. I only use D on the

highway with less traffic. If you need to use D, you have to quickly

depress the gas pass 4k RPM. If you slowly press the pedal, you`ll just

hear the engine reving higher with no torque.....This ain`t a Bimmer were

you can feel the torque at 2.5k rpm... I drive 99% manual mode, and I feel

much safer bec. of the instant torque available when needed.

Regarding the vibration, that`s when you are to slow and stuck in a

smaller gear (over drive). You can feel that if you put it in manual and drive

20miles using 4th (if it will allow you ) or 10 MPH in 3rd.

EX35 is a perfect car for me. I just wish it had more torque like the G35.

I`m just not used to the noisy exhaust the G35 produce. It was cool at

first, but later on the sound makes me tired...

[EX35-V]

I had a similar problem with the transmission a few weeks ago. The symptom appeared one early morning when the temperature was below 40-degree. As a ritual, I always waited for at least a minute or two when starting the engine prior initate driving. That day, the transmission acted abmormally. It shifted abruptedly, both upshift/downshift, even after 15 mins of driving. I notified the dealer and they mentioned that there was a chip/sensor which suppose to signal the transmission to behave per different driving style input. Anyhow, the symptom disappeared later that afternoon but I still brought the vehicle to the dealer for have the sensor replace. The next day, it happens again. I was pissed and notified the dealer again. They requested that I should bring the vehicle to them and mimick the systom with their tech on board. But again, the transmission acted normal later that day so I decided not to bring it to the dealer. To this day, the transmission appears to function normally. I think perhaps the sensor was malfunction due to changes in temperature or that the electrical signal was poor on the sensor. Perhaps a good "hyper ground wires" is needed to cure this problem? Below is the link of the product made for the G37. I can attest that the "hyper ground wire" works on my other vehicles that I had installed this mod.

http://www.racinglab.com/hyper....html

[Punjab]

i seen that happen too i attributed it to some type of transmission protection system that they dont tell anyone about just like the audio protection that they have on most radios to protect speakers by rolling off the highs and lows at high volumes, maybe theirs is a cold transmission software check so it prevents early stage damage or just a poorly written software code for cold trans startup ..

[SHB001]

I am almost through driving recommended 1K miles dealer asked me to put on the car through more aggressive driving and after they reset car's memory. Nothing has changed. After 15-20 minutes of normal behavior, engine starts to vibrate in speeds between 30-40 mph in city driving. I informed the dealer of this and was told there was nothing they could do and the overdrive feature is there to save gas. What i don't understand is how can the car be in 5th gear at 40 mph in moderate city traffic? Is that what overdrive does to save gas? No wonder the car starts to vibrate and is sluggish. As soon as I switch to manual, it downshifts to 4th and vibration disapperas. I've been asked by delaer to give it quarter more gas when vibration starts. It works, but I almost hit the car in front of me a few times in aggrevation. Applying more gas is not the solution. I have never had a car behaving this way. Could this be caused by a bad sensor or something similar and not be overdrive related at all? I am not sure what exactly senses and shifts gears in automatic. Couple of days ago the symptoms disappeared and I thought finally, it's adjusted to my driving habits as dealer claimed it would do. But no such luck, it came back right the next day. Am I the only one with this problem? This is getting frustrating more and more with every passing mile. EX AWD/ 2 months old.

[302@12psi]

What brand/type of fuel are you using?

Another fellow MD'er and I do not have that issue. Althrough I hardly ever sit in traffic but I havent noticed your complaint. If you are using lower quality fuel it's possible that the car is knocking and/or defending against what it see's as a pre-knock situation and is jerking around a bit.

You could always try another dealership if this one is of the mind set that you are a paranoid owner. If that doesnt work then I'd simple just use DS when you are in stop and go traffic.

[kamiguy]

Had a similar problem with my Nissan Xtrail before I got rid of it. The transmission wouldn't downshift at city speeds, even on a slight incline, resulting in the lugging feeling. I had to shift manually. As mentioned. try another dealer since I have never experienced that issue with my EX. Good luck!

[aft981]

A side issue (mine drives perfectly, so no problems with that), but I've noticed some people still call the top gear 'overdrive'. Why?!

Maybe this is because I'm from the UK, where 90% of cars are manual, and you have to take your test in a manual car or else your license only lets you drive automatics. However, my EX has 5 gears. 1 through 5. There is no overdrive. 5th gear is 5th gear. It's the one above 4th.

With the new 7 speed box Infiniti are bringing out...7th gear is just that. The one above 6th.

[AWGD8]

Overdrive means the final drive(tailshaft) rotates faster than the engine. On 5- speed transmissions, 4th has a 1:1 ratio and 5th is in overdrive.

"A transmission in which the highest gear ratio is less than a one-to-one ratio. This means the drive shaft turns faster than the engine crankshaft. The overdrive feature saves fuel and, because the engine runs slower, engine wear and noise are reduced"

As you can see our EX35 5th gear is less than 1 which is 0.84 . This means engine speed turns slower (ratio 0.84) than the transmission (ratio 1)

This means a 3/4 Engine revolution will turn the transmission 1 complete revolution. This causes low engine RPM but more wheel revolution.

If you look at the 4th gear it says 1:1 means direct drive which is one is to one. This means 1 engine revolution = 1 transmission revolution.

So with new EX37 with 7 speed transmission, anything above the direct drive which is 1:1 is gonna be an overdive... I guess the EX37 might have 3 over drive gears.....

ex35 awdDrivetrain : All Wheel Drive Trans Order Code : Trans Type : 5 Trans Description Cont. : Automatic w/OD Trans Description Cont. Again : First Gear Ratio 3.84 Second Gear Ratio 2.35 Third Gear Ratio 1.53 Fourth Gear Rato 1.00 Fifth Gear Ratio 0.84 Sixth Gear Ratio Reverse Ratio 2.76 Clutch Size (in) : Final Drive Axle Ratio () : 3.69

[dividedhighw]

... I guess the EX37 might have 3 over drive gears.....

I hope NOT!! On a 7-speed, the car should be engineered so the ratios for the first 6 are spaced closer together to give it more responsiveness (especially given that max torque isn't available until higher RPMs), leaving the "tallest" gear for overdrive.

Mind you, Infiniti's various design/engineering decisions on this car have made me say ... so, it could well be that way on this point also!

Examples include:- ridiculous limit on number of files/folders for CF card- copying of MP3s from CF to hard drive disallowed- can't browse/scroll available songs on hard drive or CF card without interrupting the current song- lack of mirror-mounted (or fender-mounted) turn indicators- ICC's behaviour of charging up to another vehicle at full-speed, only to slam on the brakes (instead of sensing the fast closing speed and easing up on the throttle to match speed at the selected following distance)- overly intrusive VDC (to the point of being dangerous)- can't close moonroof or rear windows with key fob (thereby neutralizing the very reason for this feature at all)- TPMS only allows 4 registered sensors (should be 8 to account for one other set of wheels)- no display of tire pressure as detected by TPMS (only a single idiot light)... etc

Cheers,David

[AWGD8]

This is from the G37 SEDAN AWD

As you can see, there are 2 overdrive gears 6th(0.86) and 7th(0.77)

It`s also a close gearing ratio from 1st to 5th. Does this mean we have to

shift it more often bec. the rpm will hit the red quicker? You know, if you

want to use the manual mode which I do 99% of the time.

First Gear Ratio 4.92 Second Gear Ratio 3.19 Third Gear Ratio 2.04 Fourth Gear Rato 1.41 Fifth Gear Ratio 1.00 Sixth Gear Ratio 0.86 Seventh Gear Ratio 0.77 Reverse Ratio 3.97 Final Drive Axle Ratio 3.36 Total Cooling System Capacity (qts): 9.0 Fuel Tank Capacity, Approx (gal): 20.0

All Wheel Drive V6 Cylinder Engine

[dividedhighw]

Good call, AWDG8 - I wouldn't be surprised if a 7-speed EX was identical or at least similar to the G37!

Anyone have specs on the EX37's 7-speed being sold in Europe?

(Since I tend to keep my cars 4 to 7 years, I'm very unlikely to trade up to a newer 7-speed anytime soon, so for me - though interesting, it's a moot point.)

Cheers,David

[SteveTheTech]

David I agree with your annoyances of this car, all things the 07-08 Gs share. For some reason the models with 4 automatic window all go up when commanded. The software technology for audio operation could use an update.

I just wanted to through my hat into the ring on this to clarify a few things that stick out to me.

First off "overdrive" refers torque converter lockup. This is the clutch device inside the bellhousing, during acceleration the stator and vanes work to multiply torque of provide a fluid coupler between the engine and transmission. At cruising speed the main operation is to apply the torque converter.That's very general non informative information. If you read some of this link the basic operation of the JATCO model RE5RO5A is broken down a little more. This is from the G35 esm but the information is the same. Check out the information starting on page TM-80. It's some good stuff. In particular lock-up control is explained as well as Adoptive shift control, both feature common in these transmissions.

Lock-up control on the EX begins at roughly 43mph with <1/8 throttle input.