She's acting up....
 

So I'm driving a bit aggresively and as I downshift from 4th to 3rth and allow the car to coast, the synchro rev perfectly matched 3rd gear revs and I let out of clutch, then something happened....

Instead of engine breaking the car maintains speed or even very slightly accelerates.(on its own with my feet completely off of all pedals) Once I apply break pressure it stops doing this. No the accelerator wasn't stuck I was curious so I tried to duplicate the action and once again the same thing. This time I put my foot behind the pedal and tried to pull out, it wasn't stuck. It only happened at right about the 4k rpm range and for only about 3 seconds.
The action felt like something was up with the Synchro system, like it was trying to bump the rpms while i was in gear

This happened about an hour ago and is definitely cause for concern. Anybody ever heard of this happening?

Well, not quite the same but related to the synchro rev...

I have the 7AT. I was under the impression that the synchro rev is only on when the tranny is in sport mode for the auto and I manually downshift. Until a few days ago this has always been the case for me.

Well this past weekend when I was coasting downhill in full auto mode with my foot completely off the throttle, the car suddenly revved twice! It was a decent rev too like up to 4k or something. I drive in full auto mode when I'm lazy or during my daily commute to work all the time. Its never gone off in full auto mode before.

I've had this happen many times with spirited on/off ramp driving. The car does feel like it accelerates, but I think it is only not braking (by the engine). I am not sure what or why the car does this - but it has done it since I have had it (Jan). It is only noticeable when I am at/near the limits in a turn (at no throttle).

i have heard of this before and more then likely what causes it is the that the rev match is designed so that when you downshift your going to be right back on the gas so it anticipates this and does it for you.

Same thing has happened to me (many times) while working through back road twisties. I'm just calling it a feature :ugh2:

Maybe the VVEL was throwing the ECU off.. interesting... lol my downshifts rarely end up near 4k

Had to bring this back alive. After driving this car for over a year, I notice it a lot more, and have the ability to recreate it. Anytime I am on a long on/off ramp from a highway, and have a good speed going, and lift off the gas (to hopefully let the car decelerate), the car maintains the speed. Being close to the edge of comfort, it does make me a little nervous, as it is close to the edge of a slipping (and I am prepared to countersteer). So there are 2 inputs, good amount of steering input, and g-forces - it is either condition (or a combo of them) that creates this problem. Anyone else out there have this issue and have you had more time to diagnose it? I am at the point now that I am going to test it around my dealership, so that when I take it in (in the next week or 2) I can show them. I would suspect those that do DEs would feel this (if it was common), on long sweeping turns (which is the only time I feel it). I also notice that it will start to decelerate once the long sweeping turn straightens out (less g force and steering input), or I slightly touch the brakes. It's actually much easier to recognize it since I have installed the FI exhaust as you don't get the decel gurgle until it goes away.

Any others? After all of these Toyota issues, I wonder if Nissan has something similar; these electronic gas pedals concern me.

I read that porsche has a feature called engine torque drag control or something like that as part of the porsche stability management program. What it does apparently is that it opens the throttle a bit so that the engine revving down doesn't rev down too quickly and cause too much drag on the rear wheels and break their traction and lead to spinning out. Perhaps the Z stability control has a similar feature?

What I am having happen is definately not a 'wanted' feature. And it doesn't rev down at all (maintains rpm), until either the turn increases radius (less g force) or I touch the brakes. Thanks though.

Why would you expect the car to significantly slow down just by lifting off the gas, especially if you are going at speed into a turn?

I don't expect it to significantly slow down, but I do expect it, due to friction, to not maintain speed, as anyone should. Cars won't maintain speed, if you don't have an input like fuel.

Very interesting. I have come across the same thing and thought it was just a placebo effect but it's just as speed works has described.

Yeah, you won't notice it, unless you are daring enough/experienced enough to take a turn at a significant speed. On a racetrack, I would feel this constanty. I scare my passengers every time I do it, but the issue I feel, scares me sometimes, and it isn't what a car is supposed to do.

I think this is calls momentum. Unless you guys shift it to a very low gear, where the rpm needs to maintain the same speed is significantly more, then you will likely not see engine breaking just by lifting off the pedal. Example: just accelerate, downhill, level pavement, etc.

As speedworks described, he takes a turn at a significant speed, that speed will maintain because of the angular momentum. Not sure what gear he is normally in, but if taking a sharp turn at like 4th or 5th gear going 65mph, simply lifting of the gas pedal will not slow the car down because the rpm needs to maintain the speed is still low. This is just an example. :)

Its not momentum, trust me, I have lots of experience at speed (on a track), and know how a car should feel/act in turns. The problem my car has, and I can assume others as well have, is that the car maintains a throttle in these situations. Its not normal, and hopefully I will be able to recreate it with a tech in the car. It does it for seconds in a long sweeping turn, so there is enough time for the car to slow (and when I say slow, I mean 1mph), you can hear the throttle (through the exhaust note not changing), until the situation changes (brakes or straightening) and then it releases the throttle. My guess is something with the g forces are causing a sensor to change.

I'll never feel it because I always downshift and accelerate into off-ramps :tup:

Yes.. it's called momentum. It's also called a heavy flywheel coupled with the fact that the engine has rev-matched so the rpm's are a spinnin!

I still have this somewhat even with my lightweight flywheel but not nearly as much as the heavy stocker.

Yeah, I accelerate out of the turn too, but I am talking going into the turn. If you are accelerating, in my situation, you will spin it. Again, momentum is not it, I can get it to do it for seconds on a long speeding turn.

Oh yeah, forgot to say, I don't use the SRM, so at the point this is happening, I am already in a gear (usually I am in 3rd at the time) for quite a few seconds.

No, no, I downshift and hit the gas going into off-ramps. It's a game..... and I never get the issue you described. I never head into off-ramps without downshifting, I guess it's just me. This issue would also have a lot to do with what gear you were in, no? In 6th, I could see where it would feel like it wasn't slowing down............

If you are accelerating into a turn, you are going to slow. I come into them at speed, brake initially, turn in, slight throttle if needed, and then you are at the edge of a spin/drift, and at the point, I will lift and ride it out a little (sometimes longer since MA doesn't develop on/off ramps well, and they become a decreasing radius), and that is when you will feel it. I am always in the sweet spot of the particular gear (usually 3rd). Steve, if you are ever in the Providence/Boston area, let me know, I will show you it.

Same with my 7AT, was going down a fairly step hill, foot off the gas just kind of coasting down at aprox. 40-45mph, the car downshifted but held the RPM at 4k. Didn't feel an increase in speed or anything, just held at 4k until I breaked. Took me by suprise but I don't think it's anything to worry about.

UPDATE: Just took it to the dealer, and was able to re-enact the issue with a tech in the car. One thing I didn't think about was putting my foot in the clutch when it happens. He suggested it, and what do you know, the car went to 4500 rpm and maintained that rpm through the turn (or until I touched the brake or the turn straightened out). So, it was definately maintaining a throttle. Those with this issue should try the same thing. Anyway, the car is in their hands now; and hopefully they call with a option/solution.

glad to hear this was reenacted with the dealer present. Please update us as this is still happening to me. And i agree it only happens at the "sweet spot" of the gear.

Quick update:
They couldn't find any obvious issue to cause the problem (checked all wiring and sensors, and found nothing). They have a call into Engineering, and are awaiting an answer of what to do next - they will have the car for a few more days. Its supposed to rain around here the rest of the week, so no biggie for me.

I also put in a complaint on the PW sideskirts not being a perfect paint fit (like all of them). Again, they will be reviewed by a corp representative when they are back in town (the run around on that one).

Well, they called today, and said I can pick it up. The dealer said that Engineering (Nissan) came back saying they are working on it, and will let me (the dealer) know when they have a fix - timing unknown.

Hmmm, disappointing.

They, Nissan Engineering, probably have to modify their algorithm used for SRM. Maybe/Hopefully enough people will complain about this issue to have it escalated so a fix (in the form of a TSB) can be pushed out sooner rather than later.

I wouldn't hold my breath in hopes of a fix to be released soon though. When they do develop a fix, it will have to go through extensive (read long) testing. :(

This ^^ sounds like a pretty logical explanation... Also notice that if you are cruising then move into neutral, when the snychro rev match kicks in (immediately), that it holds the revs for a long time before realizing that you are not moving into another gear (due to coasting in neutral) and then slowly allows itself to wind down. Thus, if you were to downshift and not manully get back on the gas, the synchro rev match is still electronically holding the throttle open for about 3 seconds or so. Because of this, any engine braking would be minimal, if any during that time period. One way to test would be to disable the syncro-rev match and try it again- you would engine brake much harder then.

Yeah this is same thing I was trying to explain in the autocross thread. Weird and threw me off the first few times it happened. Now I just run the car with the SRM off without issues.

^^^ Guys, I don't use the SRM - it is always off, so these explanations aren't in line with the situation. Also, this happens when the car is in gear already, not in neutral, or not in a position where any shifting is about to happen. It happens in gear, at fast speeds around turns. Definately a problem, they recognized that, but don't have a solution. What was interesting is when I did it with the tech in the car, and then put my foot in the clutch (no movement of the shifter), it moved the rpms to 4500, when at the time I was probably at around 4100-4200.

Those of you who noticed it in an autocross, take a long sweeping on/off ramp, at speed, in a single gear, take your foot off the gas (at the point you need to because you are bringing a lot of speed into the turn), and then you will feel the problem -feels like the gas is still on (steady, not increasing).

I've had the car for a little over a month and have about 1600 miles on it. I've just started to push it after break-in and I noticed this for the first time yesterday going onto an on-ramp. I have the base model, no sports package, no sync rev, so that takes out sync rev as the culprit.

I was approaching the on ramp pretty fast in 3rd, I rev-matched and put it into second at about 4k rmp (possibly higher), the car was in gear before I took the turn and noticed it's not engine breaking for s***! I almost went into the f'ing curb and if I wasn't somewhat experienced I probably would have.

This being a heavy flywheel issue SOMEWHAT makes sense from the way it felt. Like the flywheel was spinning and because it's heavy its momentum kept carrying the gear? F! I don't f'in know. :mad:

That's it. I would suspect quite a few people have it, they just haven't put the car into the situation. Please take it to the dealer, so there are more complaints to the problem. They supposedly give a case number by customer name (pm me if you want my name to reference). Obviously, they haven't come back with a solution yet.

This is a cause of major concern for me as I was planning on picking a Z this weekend. Do you guys feel that the issues you are seeing are an isolated problem (lemon vehicle) or a general engineering problem that all cars have? Someone in this thread mentioned that this is happening to
their 1 month old car, which I presume is a 2010.

The issue has gone on record with Nissan, as mentioned by one of the posting members in this thread. Given the advent of the Toyota's issues, it is (hopefully) unlikely that Nissan will not act on this if it is a problem. The final decision of buying the Z is up to you. You will be getting a lot of automobile for your money if you buy one.

All vehicles have issues, and all manufacturers address them in different ways. This issue sounds serious enough to warrant Nissan doing something as the car is not entering into a limp mode in what Nissan is essentially saying is a fail-safe measure—it is doing something out of the ordinary (unless, Nissan states that engine braking is not ordinary...pretty damn hard to do in the enthusiast world).

Rep point to speedworks!

Yeah I only had it happen during Auto-x. I'll try to replicate somewhere safe since the car is going to Korea with me. If there is something Nissan could do I would like to get it done before then.

why would the problem only happen on turns? how would g forces affect the throttling system? do the cars even have g sensors? if so they'd tie in with vdc. but vdc only cuts engine power, not increase it.

Can't answer this question. I did get the impression from the service manager that Nissan engineering kind of already knew of the issue, and that it was related to the ecu program (which I believe). I used to own an SVT Focus when I worked for Ford, I was able to work with the SVT engineers to diagnose an issue with the throttle map (it would surge at constant cruising speeds) - it took them some time then to develop a new map for the ecu. So much electronics in these things, this issue doesn't surprise me. As for the other person above concerned about buying the car - all cars have issues, and my guess is most people won't be putting their cars in this situation that often (unless you drive close to the limit on turns). It bothers me when I feel it, but I now can predict it. I just look forward to the fix - ecu update is my guess.

still doesn't answer why it only happens on turns. are there any g force sensors or sensors for steering angle or yaw?

I'll take it in to the dealer as soon as I get a chance...I'll let you know what they say.

Pharmacist, do you have a bigger pic of your avatar?