My wife is the proud owner of a Max 2005 SL with 900 miles and absolutely loves it. What she is trying to figure out if the transmission is working correctly. When she goes down a long hill and uses the brakes slightly it downshifts into 3rd gear while still maintaining a speed of at least 50 mph and tachs up to about 3000 rpm. Then at the bottom of the hill she has to throttle it to up-shift. What I am wonder is if this is normal to help slow the car or the transmission is not working correctly. This certainly feels weird and will take getting used to if this is normal. Other than that the transmission seems to work normally… Thanks in advance for and feedback on this…

 

you know what... we just bought a new maxima 05 sl 2 months ago and i've noticed that with the rpm.. kinda weird but i got used to it.. I want to avoid bringing a new car to the shop unless it REALLY needs to go, I hate tinkering unless I'm doing it.. lol

 

im pretty sure its the electronic drive by wire, or something along those lines.. its the same way when you have it in cruise control going down a hill you will feel a tug and pull sensation..

 

if it helps any, my 2004 Titan did the same thing. I thought it was actually pretty neat that it did that. The vehicle senses you are braking going downhill and actually uses the tranny to slow it down.

 

it is very normal. Honda calls it grade logic control. I don't know what nissan
calls it. however it seems like that feature is pretty much standard on most
vehicles now and some manufacturer like nissan don't even list it as goodies anymore.

It downshifts if it senses that you need engine braking which will reduce brake overheating on downhills. on very steep uphills, it downshifts and hold the lower gear to avoid frequent gear changes.

 

NORMAL. engine breaking is what manual drivers should do. but it usually is only noticeable when your decending fairly quickly

 

does it do it by itself or do we make it do it?

cause the car on auto tries do drive at the lowest possible rpm to save gas, now if you are braking the rpm's are dropping putting the car in a down shifting situation to stay runing.. cause if going down the hill, if you stay steady on the throttle and don't brake, it won't do that..

this is no option, the car is doing exacly what it has to do.... anyone agree?

 

when decending at a high speed, if you apply a lot of brake, it will downshift enough that the RPM is noticeably very high. this gives you assistance and more control.

I experience it when I'm in a hurry and going faster than I know I should going downhill with curves that require braking.

 

I notice it alot during low speed driving (30+ range) It slows down with higher RPM then catches itself. There was a TSB for this but my vin# didnt fall in line. Sometimes it almost seems dangerous, Ill be creeping in traffic and then give it a little and it jerks its self into place...? Seems funny, but maybe thats how its made?

 

My '04 SL has done this from day one. It startled me the first few months. I have gradually grown used to it, and now sort of appreciate it.

It usually happens when I am going down a fairly steep slope at less than 25 mph, and have no foot on any pedal. The engine compression kicking in as a result of the tranny downshifting sometimes allows me to avoid using the brakes to slow the car.

But every time it happens, I notice it. Never had this 'feature' on any other vehicle in over 55 years of driving.

 

It was a new one on me too. A smart automatic transmission, who'd have thunk it? I can forgive myself for not buying a 6-speed.

 

In May of 2003, before I finally setteled on a Silver Max with a 6-speed manual, I test drove an SE with automatic. I drove up to my house (1200 feet above the city). I did not experience this trannie feature driving back down hill again. (Is it only in the SL?)

I got the 6-speed because of the control it offered and the fact that I could use engine braking to keep from prematurely wearing out the brakes. I still like the added control a manual trannie gives, but this certainly seems like a nice feature for an auto trannie. In my previous car (98 Olds) I think that I substantially shortened the live of the auto trannie because I used lower gears in that GM trannie for engine braking. (That trannie failed just as the warranty was ending.) Suspect the Nissan trannie is better built.

 

SilverMax_04 - Until February, 2004, the SL had a four speed auto. I have no idea if that trannie had the trait being discussed here. But SLs built from February 6th, 2004 until the present have exactly the same five speed tiptronic tranny as the SEs.

I use the tiptronic feature to reduce braking effort by using engine compression every time I have to navigate down long steep curvy roads, such as dropping from the crest of the Blue Ridge to the piedmont in North Carolina. I frequently travel several places there where the road loses between one and two thousand feet in elevation in only half a dozen miles of sharp curves.

Earlier generation Maxima auto trannies had the ability to keep the tranny in lower gears via the '1' and '2' positions on the tranny gear selection dial. I have always used these on steep descents (and steep climbs) on my Maximas, and so far, have never had any problems with the trannies.

 

Most German cars have this from what I know... I've experienced it first hand in my coupe and my in-laws ML. I'm pretty sure VW touts it as a feature in their Touraeg thing (or whatever it's called), and they call it "Hill Descent Control" or something like that.

Maybe this is VDC-related on the Max? I know I haven't felt it on my SL yet (don't have that option), but on my MB it doesn't kick in if I turn off traction control (don't ask ).

It's picky about when it kicks in though... you have to be going down a steep hill, with the throttle less than 5% and the vehicle has to be accelerating. I suppose the car feels that it's going down a hill (tilt sensor), that you're not on the gas and that it's gaining speed, so it engine-brakes for you.

 

Thanks everyone...

Does anyone know if turning off the VDC control has any affect on this????

 

Well i use steptronic to down shift and slow down my car alot (auto tranny) is that going to hurt my transmission or is it ok?

 

I am pretty sure it's alright. I had to compromise with my wife otherwise I would have a 6-speed and my fun-o-meter would be pegged. It won't down shift until the engine is at a safe enough RPM anyway.

I don't like the pause though. For instance, going down to 1st catches me off guard everytime, and I was almost rear-ended once because of the lag between downshifts.

 

bertl - I would guess the VDC might not be involved here, as only around 5% to 10% of '04 Maximas even have the VDC option, and only around 15% to 20% of the '05s I have looked at on the Nissan site have VDC.

The sensors that trigger the VDC system are looking for situations in which the car is not going where it is pointed, which indicates the driver may be losing control of the vehicle.

Unlike traction control, which helps most in startup and low speed conditions, especially when the road is slick or icy, VDC is at its best when the vehicle is moving at or near highway speeds. About the only way a car would be out of control at low speeds would be when the road is slick or icy. But VDC would not be very effective on slick roads, and totally ineffective in icy conditions.

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belal242 - As I indicated in my post back at 6:04 PM Thursday, downshifting to use engine compression for braking has never caused any problem with my trannys.

BUT - I downshift at the top of downgrades while moving very slowly, then let the compression do its thing all the way down. This avoids any sudden stress on the tranny. Dropping the tranny into a low gear in order to slow the car from speed is an entirely different situation, and puts considerable stress on the tranny. I would not recommend regular use of the tranny as a serious braking mechanism in everyday driving.

Some heavy diesel trucks have a device that allows use of the engine compression to slow down from speed. The device is called 'Jake Brakes', and the tranny is designed to handle this. But I would not think the Maxima tranny was designed for frequent use in braking from speed, except possibly with a manual tranny, where careful handling of the clutch would avoid the sudden jerk on the tranny.

 

Could not agree more with light about: "Dropping the tranny into a low gear in order to slow the car from speed is an entirely different situation, and puts considerable stress on the tranny. I would not recommend regular use of the tranny as a serious braking mechanism in everyday driving." The bigger the engine RPM difference between gears, the more stress there will be on the auto trannie. This is even true to some extent for manuals. But with manual trannies, I think that double clutching helps to substantially reduce this strees because (if done right) the engine, lower gear and drive shaft are all going closer to the proper speed (ie the speed they will be going when all are meshed together and the clutch is all the way out). Double clutching is a somewhat better description of what light calls: "careful handling of the clutch" -- althought he could also mean slowly engaging the clutch to reduce the strees. Of the two, I prefer double clutching.

 

Thank you Lightonthehill and Silvermax i guess i need to stop using the down shift to slow my car down. But i think in sudden stops it might be ok to use given the fact that is really helps slow down the car, and its much better than running into somones bumper but i will most def keep your suggestions in mind.

 

i got a 05 SE and when i go down hill i notice the same thing, but i got use to it. So before i reach a hill i just use the manumatic mode.

 

I have the 4-speed auto, and it does behave pretty much exactly as you guys have described. So I presume that it has the same "feature", though I certainly don't know for sure.

 

SilverMax04 - You are correct that I was meaning 'double clutching'. I avoided the terminology because I was not sure if many posters here were familiar with it.

You mentioned preferring 'double clutching' over slowly engaging the clutch. That is because you are wise enough to know that slowly engaging the clutch when the tranny and engine speeds are not in sync simply moves the stress and wear from the tranny and puts it on the clutch.

 

Correct light, it just moves the stress (and wear) to the clutch. I thought that the young guys on this site should learn about "old techniques" that still work -- and are very effective -- today. Double clutching is one of those. It was used by truck and bus drivers for years to keep from clashing non-synchronized gears in their rigs (where some are today auto-trannies). {I first remember double clutching when riding a Greyhound bus in the early 50s. I sat where I could see the driver work the clutch and the gear shift. I asked him why he did that, and he explained it to me. Without synchronizers, he had to double clutch every shift, both up and down, to put a spin on each gear he was about to use.}

But even with synchronizers, double clutching is a good technique to master. If any are curious, light or I can describe the technique.