[Cryogenix1]

Yes it is under service functions then engine option you can set it drive mode or idle mode when switching between the two I could hear something happening. No change with the vibration when switching between the options though unfortunately.

I wonder if you keep the car running and look at one of the affected mounts, and then change settings, you could see what it's doing. I wonder if what you heard was the valve turning as shown in the video. Too bad it didn't work. Maybe try fast acceleration and fast braking action. And I'm not slamming the brake pedal so the car skids, but the car slows VERY rapidly and I let off once I've slowed to around 10 MPH. The braking event lasts maybe a 1-2 seconds going from 65 down to 10 MPH.

 

[jholland757961]

I wonder if you keep the car running and look at one of the affected mounts, and then change settings, you could see what it's doing. I wonder if what you heard was the valve turning as shown in the video. Too bad it didn't work. Maybe try fast acceleration and fast braking action. And I'm not slamming the brake pedal so the car skids, but the car slows VERY rapidly and I let off once I've slowed to around 10 MPH. The braking event lasts maybe a 1-2 seconds going from 65 down to 10 MPH.

I will have to give that a go tomorrow morning and see what happens. I've highly considered disconnecting the negative battery cable and leaving it undone overnight just to see what would happen. Allow it to maybe reset the TCM

 

[Cryogenix1]

CVT learnings can be cleared by erasing TCM memory (after which it will be necessary to write calibration data and to perform "clutch point learning" procedure).
"clutch point learning" by the way... Maybe results of this learning also influencing what's happening at 1000rpm.

Engine learnings also resettable and this is easier - no need to do anything afterwards.


Engine for example continuously broadcasts current estimated torque lbft it produces and CVT somehow uses these numbers. So if real torque is noticeably different from the expected value then CVT can go rough.

Thanks for the insight. I was actually thinking about some system other than the CVT that may have some learning process that's trying to adjust things somewhere, and is setting values/parameters that don't actually make sense, or that make sense in the moment but later aren't cleared and brought back to normal. I don't know if the CVT is that hyper-sensitively influenced by a minor pedal release/depression. Particularly on the pedal release which feels like a nudge let-up and isn't an extreme act. I can't imagine the CVT would produce such a rumble and then it's gone in a fraction of a second by an almost non-event event. Then, again, we are talking about an electronics system, so things will react instantly as opposed to a cable-driven pedal which will likely have some fractional time delay when compared to electrical signals communicating something.

 

[Cryogenix1]

I will have to give that a go tomorrow morning and see what happens. I've highly considered disconnecting the negative battery cable and leaving it undone overnight just to see what would happen. Allow it to maybe reset the TCM

You can try, but prior to my car suddenly coming out of the rumble for months, I hadn't disconnected the NEG battery lead or anything. I did so while the rumble was already gone (due to a stereo glitch), and the rumble didn't return until a few months later (meaning a few days ago).

 

[Cryogenix1]

Rumble was present this morning, only quieter. Oddly, rumble was not there while using cruise. Gas pedal response was actually good. Later in the morning after shopping for about about 15 minutes, I fired up MO and there was a "swarm of insects" sound coming from what seemed to be the driver's side area beneath the hood. It was noticeable prior to shifting from P to D, and still noticeable after shifting to D and starting forward. Nothing made it change its frequency or go away. This was not the same "chainsaw" or "swarm of bees" noise I originally posted about last year.

Went into a place for about an hour, came back out and started the car and that insect noise wasn't there. Maybe noise from the master cylinder? Rumble and conditions were still the same as earlier in that morning, but the vibration aspect of the rumble problem did not seem obvious.

 

[jholland757961]

Update: I tried the braking thing you were talking about and my rumble is gone. I ran it up to 70 and braked down to 20 and took off again then when slowing down for a light I did some aggressive braking just for extra assurance I will update when it returns. Seems to be a temporary fix at least or could even be a permanent fix but I'm not holding my breath 😆

 

[Cryogenix1]

My rumble is basically the same as yesterday: a bit quieter with less vibration and good pedal response.

It's never been a permanent fix for me; lasts a handful of days, if that. But at the very least it does seem to quiet the rumble and the vibration by maybe 70% (when it's not eliminated completely by doing that) so something happening during high-RPM events (or fast braking, accelerating) is affecting something that's making things change.

Just another piece of the jigsaw. I think we have too many similar edge pieces at the moment to conclude much of anything.

I think my new line of thinking is going to be the IPDM and surrounding relays/fuses in various boxes. I noticed there are a couple of capacitors in that area, and was thinking maybe something's not discharging correctly, or maybe an applicable relay is hyper-clicking and causing the swarm of insects noise. While that insect noise and rumble don't appear to be connected, you never know. BTW, the insect noise hasn't returned.

 

[jholland757961]

Update: just as expected my rumble is back I knew it wouldn't last

 

[Cryogenix1]

The rumble-vibration on mine was a bit more noticeable yesterday under manual pedal, but is still not there when I use fixed cruise.

@jholland757961, have you tried using fixed cruise control to see if the rumble still happens?

 

[jholland757961]

The rumble-vibration on mine was a bit more noticeable yesterday under manual pedal, but is still not there when I use fixed cruise.

@jholland757961, have you tried using fixed cruise control to see if the rumble still happens?

I did after I seen you mention it and from what I recall it still did it. I did notice from time to time doing the misfire monitoring on the cvt app that it would show a misfire on cyl 2 and cyl 6 plugs aren't even supposed to be due until 100k. The misfire doesn't show up every drive either.

 

[Cryogenix1]

Unfortunately, the rumble actually is happening now (again) with cruise engaged, but only when there's slack acceleration such as when approaching the base of a hill where cruise is a little late to accelerate because it doesn't know an incline is coming, which causes the RPMs to drop to 1000 before acceleration kicks in. Once going uphill or along a flat road or downhill, the rumble isn't there. Somehow on flat roads at a constant speed the cruise system is keeping the RPMs around 1200-1300, which is typically out of the rumble zone. When I hold any speed manually with the pedal, the rumble is always there as RPMs lock in at 1000.

As for your misfires, there could be something wrong with those two ignition coils. Plugs can go bad before others that were installed at the same time. In a different car I had one of six plugs have its center electrode collapse and go crooked after 95,000 miles, and it was misfiring and throwing a code. You have the advantage of very easy access to those grille-side coils. Easy test: swap coils 2 and 4 and see if the misfire carries over to 4 and if 2 becomes fine. If it does, the coil is probably failing. If not, you may have a bad plug on 2, or maybe a connector/wiring issue, or something going on with the valves or a fuel injector, etc, etc.

If the plastic engine cover is already off (I tossed mine as soon as the car's warranty expired) all you need is a 10mm socket, a short extension w/ratchet and you can swap those out in less than five minutes. If the cover is still there, it may take 15 minutes and some patience. After that test, you can swap 4 with 6 (using 4's original coil) - you might want to place a piece of tape on the tops of the coils and jot down each one's original cylinder position.

 

[jholland757961]

Unfortunately, the rumble actually is happening now (again) with cruise engaged, but only when there's slack acceleration such as when approaching the base of a hill where cruise is a little late to accelerate because it doesn't know an incline is coming, which causes the RPMs to drop to 1000 before acceleration kicks in. Once going uphill or along a flat road or downhill, the rumble isn't there. Somehow on flat roads at a constant speed the cruise system is keeping the RPMs around 1200-1300, which is typically out of the rumble zone. When I hold any speed manually with the pedal, the rumble is always there as RPMs lock in at 1000.

As for your misfires, there could be something wrong with those two ignition coils. Plugs can go bad before others that were installed at the same time. In a different car I had one of six plugs have its center electrode collapse and go crooked after 95,000 miles, and it was misfiring and throwing a code. You have the advantage of very easy access to those grille-side coils. Easy test: swap coils 2 and 4 and see if the misfire carries over to 4 and if 2 becomes fine. If it does, the coil is probably failing. If not, you may have a bad plug on 2, or maybe a connector/wiring issue, or something going on with the valves or a fuel injector, etc, etc.

If the plastic engine cover is already off (I tossed mine as soon as the car's warranty expired) all you need is a 10mm socket, a short extension w/ratchet and you can swap those out in less than five minutes. If the cover is still there, it may take 15 minutes and some patience. After that test, you can swap 4 with 6 (using 4's original coil) - you might want to place a piece of tape on the tops of the coils and jot down each one's original cylinder position.

I went ahead today since I've been busy the past few days and installed 3 new plugs on that side. Easy access took me about 25 mins to change them all. Drove the car no more misfires car drove alot better but the rumble was still present. Just this time not nearly as bad and it seemed harder to get it to drop to a 1000 rpms. Doing a aggressive stop the other day remedy the issue completely which I find crazy makes me wonder what hard braking had to do with it. I did read somewhere awhile back about the front sway bar end links causing a hum at certain rpms but I find that hard to believe. And it just crossed my mind yesterday I read that back in the winter last year that's why I never bothered messing with them

 

[Cryogenix1]

Just an observation I hadn't really made with great clarity until this morning. Complicated to explain the details and process/steps, so I won't bother.

Under foot control, if the RPMs are at 1100 with no rumble present, if I barely touch the gas pedal the tach needle drops to 1000 RPMs and the rumble appears.

Why I find this important is because the typical response for a call for more gas/acceleration should result in an RPM increase, not decrease.

To update, the rumble-vibration is still there under foot control and cruise.

 

[jholland757961]

Just an observation I hadn't really made with great clarity until this morning. Complicated to explain the details and process/steps, so I won't bother.

Under foot control, if the RPMs are at 1100 with no rumble present, if I barely touch the gas pedal the tach needle drops to 1000 RPMs.

Why I find this important is because the typical response for a call for more gas/acceleration should result in an RPM increase, not decrease.

To update, the rumble-vibration is still there under foot control and cruise.

I've noticed on mine if I'll quickly mash the gas to the floor 2 or 3 times rpms will jump up and stay around 1500 rpms and at that point under light throttle rpms stay around 1800-2000 now. going up hill under medium throttle about 3000 this occured after changing the 3 misfiring plugs I had but it still occasionally drops back down to 1000 when cruising. I'm stomped on what could be the fix it's clearly not normal if it can be made go away for awhile and no matter what I do I can't get it to return then randomly it does.

 

[Cryogenix1]

It doesn't appear to be a product of the gas pedal, since it's happening under cruise. I was thinking about the ECM (or whatever's doing it) constantly calculating fuel economy, and wondering if something is stuck in a loop and constantly querying some aspect of the fuel/air system and causing a delay in things. Maybe something's being a data/voltage hog and causing a delay in fuel/air demands. Not sure how things are tied into one another.

I might see if I can disable that fuel economy thing by pulling a fuse. Maybe during a particular event something related to that system is retaining a value that's screwing everything up. Again, maybe even a bad capacitor.

 

[jholland757961]

It doesn't appear to be a product of the gas pedal, since it's happening under cruise. I was thinking about the ECM (or whatever's doing it) constantly calculating fuel economy, and wondering if something is stuck in a loop and constantly querying some aspect of the fuel/air system and causing a delay in things. Maybe something's being a data/voltage hog and causing the delay in fuel/air demands.

That could be a possibility I seen when the altimas were doing that they shimmed the alternator and it fixed the issue but the alternator is p.i.t.a to get to so I never tried it

 

[Cryogenix1]

I read where shimming solved a vibration-rattle in an Altima, but not a rumble. Another where someone said their rumble was solved by redoing an exhaust hanger (Altima). It seems maybe the Altima 2.5 has the rumble-vibration, but at a higher RPM range of 1300-1500. There are a few posts about the Altima 3.5 having some kind of lugging/vibration somewhere around 1250 RPM, along with a Maxima. On the latter, the dealership reflashed the CVT (TCM/EEPROM ??) and the problem was solved. However, it's possible the problem returned months later and the poster never returned to let others know.

https://www.nissanclub.com/posts/4934466/

The thing to always keep in mind is, it's happened on a brand new 3rd Gen MO and on ones after lots of miles were put on. The problem has to fit those extremes and a solution must make sense within both those instances. I'd say there's more of a chance that some electronics component has a glitch than something mechanical has. That is, unless something like the throttle valve was damaged during installation and it was seating wrong, causing a new car to have the rumble. Then with later cars, perhaps carbon build-up along the throttle valve's edges (or its chamber) or over-stomping the gas pedal changed the orientation of the throttle valve so it matched the mis-seating of the new MO's TV, and so both have the rumble. Too many scenarios to consider...

 

[jholland757961]

I read where shimming solved a vibration-rattle in an Altima, but not a rumble. Another where someone said their rumble was solved by redoing an exhaust hanger (Altima). It seems maybe the Altima 2.5 has the rumble-vibration, but at a higher RPM range of 1300-1500. There are a few posts about the Altima 3.5 having some kind of lugging/vibration somewhere around 1250 RPM, along with a Maxima. On the latter, the dealership reflashed the CVT (TCM/EEPROM ??) and the problem was solved. However, it's possible the problem returned months later and the poster never returned to let others know.

https://www.nissanclub.com/posts/4934466/

The thing to always keep in mind is, it's happened on a brand new 3rd Gen MO and on ones after lots of miles were put on. The problem has to fit those extremes and a solution must make sense within both those instances. I'd say there's more of a chance that some electronics component has a glitch than something mechanical has. That is, unless something like the throttle valve was damaged during installation and it was seating wrong, causing a new car to have the rumble. Then with later cars, perhaps carbon build-up along the throttle valve's edges (or its chamber) or over-stomping the gas pedal changed the orientation of the throttle valve so it matched the mis-seating of the new MO's TV, and so both have the rumble. Too many scenarios to consider...

Very true I hope to run up on a permeant fix one of these days and can give it to the world so they can enjoy their mo's. the other day when I did the braking thing it was completely gone not even a faint sound of it at 1000 rpms but when I drove it home and shut it off it was back the next day. tried the braking thing again but it wouldn't go away that time very weird gremlin for sure .

 

[Cryogenix1]

I might be looking at this from the wrong angle. Instead of trying to determine what's causing the rumble, maybe it would be easier to figure out what under the hood could produce such a loud rumble and a vibration (or that triggers a vibration once the rumble begins) from a simple, barely touched gas pedal event.

Based on what I'm experiencing with everything so far, my best guess is it's something on the top of the engine. I'm thinking the vacuum system or a power valve actuator or the throttle valve/throttle body. The last two examples both revolve around volumes of air being funneled into various-sized chambers where there's a chance for turbulence and back-pressure to create resonating sounds that could possibly stimulate a butterfly to flutter oddly and create a subtle change in how things work. Problem is, I don't know if something like this should produce a trouble code or might only be revealed monitoring live data to see what's happening with things. Since the intake is kind of tucked up closer to the dash, it might not take much noise or vibration from some part of it to make the driver feel it's coming from something far more significant, like the CVT.

Once the "where" is figured out, it might be easier to zero in on the "what" of things as the catalyst.

I think what I need to do first is record under the hood to try to figure out where the sound is loudest or when something changes in tone, then go from there. I'm also going to pay greater attention to the sensations from the steering wheel, floorboards, gear shifter arm and whatnot to figure out how extensive the vibration is during the rumble.

 

[Cryogenix1]

Recording was pointless while driving. Too much wind noise. Will have to use foam over the camera mic to try to diffuse that.

I think the vibration is too strong to be produced by something in, on or around the intake, although it's possible something there is the trigger for the engine or CVT acting differently. I can feel the vibration in the shifter, the door armrest, the windows, seats, glovebox, floorboard...it's all over. It's not shaking the car to pieces, but there's a noticeable increase in vibrations throughout the car once the rumble starts.

Something else I've noticed... I can't use the gas pedal to hold a specific RPM range between 1200-2900. Something is happening where even if I hold the pedal steady when it first reaches 2500, it will drop by itself, then climb a little, then drop a little, then climb, then drop to 1000 and stay there. And I now have to depress the gas pedal about 1/2" in order to get any response from the engine. I can hold RPM at or above 3000, just nowhere below that. That has to be significant. Not sure how I can test to see if that same condition exists under cruise control, though. Being unable to hold a specific RPM seems to reflect something is constantly at odds with the pedal's electronics or throttle control; possibly even fluctuating voltage or (as I posted earlier) something constantly querying another part of the system which is somehow interfering with things. It almost seems like something is trying to force better fuel efficiency by reducing the RPMs whenever possible.

I'd love to know if anyone with the rumble has the same problem holding RPM. Or, if those with a 3rd Gen and no rumble have the same issue, which probably means the car's gas pedal can't be micro-controlled, possibly due to all the electronics stuff happening.