Hard Acceleration Vibration

[prelude48]

Hey Guys,
I have a 2002 Qx4, its pretty much stock and has 219,000km.

When i accelerate hard from a slow speed (around 20-30kmhr) i get a nasty little vibration. Its a fast and relatively hard vibration that is only felt through the body (floor, seat etc) I searched all over the net and came up with nothing. All other speeds are fine at hard acceleration and its always driven smooth in town and at highway speeds. Some times its worse then others.

Any insight would be helpful.

Thanks

[EsotericImage]

sounds like a broken motor mount/mounts to me.. but maybe someone else will chime in who has experience with this particular issue.

[ARKQX33V6]

Check tire balance, drive shaft u joints, brakes grabbing, tire pressures, motor mounts, slippage of torque converter, transmission oil, engine misfire, any codes coming up?

[prelude48]

I am unclear how tire balance and inflation would effect hard acceleration vibration as well as brake grabbing. Motor mounts i will check, transmission fluid was changed to synthetic no that long ago.

I have no codes and if it was a misfire i would get a code so that eliminates that i guess. I did research the torque converter and that also does not seem to fall under the symptoms category. The drive shaft and U-Joints will have to be checked.

Thanks for your input.

[ARKQX33V6]

Vibration and noises are very difficult to diagnose from afar, but as mentioned all things can and cause certain vibrations

[ARKQX33V6]

In the body from the rear is a nasty little vibration, right? In 2 wheel High range
Drive line components as drive shaft, bearings of rear axle, brake drums too tight to brake shoes, e brake mal adjusted and too tight, rear tire balance will vibrate floor of vehicle,

At the very least check it out and get back. If not these things may be others.

A uni body vehicle is like a drum skin under tension...a vibration anywhere will transmit anywhere

[VG33QX4]

i had a weird problem like this and it wound up being the tps connectors were loose at the throttle body. they looked like they were legit but they were not i had to zip tie them as the harness clips were broken. check there first i bought new plug wires and changed plugs and didnt change a thing. 10cents in zip ties cured my issue

[prelude48]

*update*
So i inspected everything underneath my truck (drive shaft u-joints, mounts etc) and couldn't find anything wrong. So i decided to put my rear axle on jack stands and put it in Drive so i could listen to things and watch etc. you know what i found? nothing!! Everything looks and sounds good (used a stethoscope) transfer case was a little noisy but all seemed good.

Thanks again for the input

[ARKQX33V6]

Nothing ,all OK? If that is the case then that vibration you feel is in relation to the truck movement over a roadway.
torque is needed, if your torque converter locks up and releases (at around 40 MPH, 60Km) the torque lock up and releasing will cause a vibration feel under load.
??? Have you had recent transmission work done, has the converter been emptied. Another possibility is the limited slip fiff acting up under heavy loads.

This is going to be trial and error on your part. But during heavy loading as in heavy throttle all drive components work hard and hydraulic operation of the transmission needs to be accurate, smooth and constant.

If anything from the throttle, to motor, to converter, to transmission then onwards to the shafts and diff rear end has a slight tendency to slip then come out of play then return all under a heavy foot will show torque ingress and then slippage thus the torque movement at play throughout the total system will pulsate and manifest as vibration. But when gentle foot pressure with the gas none of this exists as said, the fault sounds to be in the drive line. The motor will do this if it misses, the TPS will also cause this but with each you should get a code.

The transmission ratios will set a code but the converter may not. The transfer case, the rear end and the brakes need to be inspected .

If you are not getting any engine or transmission codes it will take careful and time consuming inspections.

Have you done any tire, wheel work just before all of this, in fact think of the recent history just before all this took place.

[fleurys]

You cannot see if a u-joint is bad just by looking at it. you need to remove the driveshaft and rotate the joint in your hand to see and feel if it is bad or starting to cup. I had the same issue as you and when I changed my ujoints it was almost perfect but I could feel a small cupping starting... it was my vibration...

[prelude48]

I didnt just look at it, i put the truck in neutral and checked it by feeling if there was any play in the joint.
What do you mean by "starting to cup?'

Thanks for you input

[fleurys]

A bad joint is not only if there's play in it. My front joint had absolutely not play in it but turning by hand felt like the needle bearings inside were not round anymore...kind of if they were starting to become square... So when I was turning the joint, it was kind of turning in steps if you get what i mean...

if you want to confirm that it is your ujoint, do this test in a STRAIGHT LINE ONLY !

1) roll at 20-30km/h and put the truck in 4hi (not auto), then hard accelerate. if it is what I think it is, the vibration should be amplified alot. Before turning, get back on 2hi.

S.

[prelude48]

did that the other night, had less vibration then what it normally does.

[fleurys]

then check your rear u-joints....by removing your rear driveshaft (4 bolts) and play with the ujoint in your hand... it really takes 10 minutes to remove and you'll be set. The ujoint should really operate freely and rotate in a linear fashion, not in steps or with difficulty...

[prelude48]

Both u joints are good, nice and smooth and feel noramal

[fleurys]

usually vibration when hard acceleration is related to parts that can move or bend when put to a stress... A ujoint is a good exemple.. a tire is not..so to be honest i'm a little perplexed... maybe a transfer case bearing or even a pignon bearing etc... but at 219k km, I would still go the route to change all the ujoints just because of what I saw and felt with my own truck... Like I said the vibration was there but the ujoints still look no bad... So... sorry I can't help more, but to give you a link to the part numbers of the joints I bought. If you decide to go this way, at least you won;t have to search for these... http://npora.ipbhost.com/index.php?show ... t&p=481906

[prelude48]

Thanks fleurys, appreciate the help

Im chatting with a mechanic from Just Answers, so far he says my differential might be the problem.

[prelude48]

Well the guy from Just Answers said it sounds like a bad transfer case. Im not sure i agree 100%.

Thanks for all the help

[fleurys]

once you find the problem, please come back here and write it. Everyone, including me, will benefit from it.

S.

[Pathfound49]

I agree. Please post any findings Prelude.

[prelude48]

The guy from "Just Answers" says tansfer case is worn. I asked him for a little more detail as "Worn" Is pretty in-descriptive.
Anyone ever heard of a bad T-case in QX or Pathfinder? I got a used price of 375 so its a good price if i have to change it.

Also, anyone know of how much play should be at the output on the transfer case? if i shake my drive shaft it has a little play there, but not to much.
Thanks

[Pathfound49]

Been told by a few folks with a lot of knowledge that "some" play is normal. Now that term can be interpreted differently by just about anybody. Without a runout gauge, my best explanation would be that if you grab the driveshaft and push it up and down or side to side, if it feels like it moves, but you can't be sure, that is "some" play.

With regard to the worn transfer case, I know there is a bearing for for the output for the rear driveshaft, and one for the front driveshaft in the transfer case. I'm about to just throw some parts at my vibration issue, and these sound like as good a place to start as any.

If anyone has ever had these replaced, could you tell me if the transfer case needs to be removed to press them in, or can it be done underneath the truck with hand tools?

Sorry for the thread hijack Prelude.

[ARKQX33V6]

When you drive in reverse do you come to a complete stop before shifting into drive and the other way do you come to a complete stop prior to a shift or are you like most, shift into D or R while the vehicle is still moving.

Shifting into the opposite gear while still on the move create extreme pressures in transmission and drive line and motor mounts.

[rigamorand]

Hey Pathfound49,

Did you ever figure out your transfer case bearing issue? Im having the same problems and I've put on new u-joints, checked the balance of the shaft, balanced tires, tightened wheel bearings and I'm still getting the vibration. I'm thinking about the transfer case bearing. Did you do it? if so how hard was it to change? did it fix the prob?

thanks

[Pathfound49]

Sorry man. I've just come to grips with it as part of my vehicles' list of flaws. I haven't made any more attempts at it. I'm basically waiting for it(whatever IT is) to wear out and break. So far i've put 17,000 miles on it and it still feels the same. Bothers me to no end, but i have no patience for it anymore.

If the cause ever jumps out from underneath my pathy and slaps me in the head, i'll post it up right quick.

[prelude48]

I have a little update

I worked at Nissan for a while and i asked all the techs there and not one had a answer, Or any help at all.
I managed to get a tech to drive my truck and feel the vibration and he didn't have a clue what it was, we put it on the hoist and checked all mounts and bushings etc and he said everything felt very good and i agreed, he also said the truck felt tight when driving. I also pulled a 02 qx4 out of the shop a while ago and floored it off the line and it did the same thing, (shaking). When a qx4 or finder came in the shop i always checked the t-case front and rear outputs and all felt like mine.

Recently i swapped out my rear gears(diff) because mine was making a weird noise and i didn't want it to f*** me over on the side of the highway, that made no difference, i also bought a 1700lb tent trailer and i pull that up to three hours away and drives fine at speeds but not when you accelerate off the line, the vibration is worse. The last thing i did was mount a digital camera on the rear axle and drive around to see if it would shake or something and you could see in the pic it did but that didnt really point me in any right direction. I kinda recall the tech saying it might be the t-case and the just answers guy said the same thing. So im not about to swap it out because it works fine and it cost 375 for a used one.

So as pathfound is doing, just wait until it gets more obvious i guess and it has gotten worse over the year that i have had the truck.

[K03sport]

have you thought that this vibration could be the nature of the beast?

Even with all of the rubber mounts, vibrations from the engine will be amplified or feel there worst when they reach the natural freq of the vehicle. Although the PF/QX4 comes with a 6-cyl engine, it is still not as smooth as it could be.

There has to be a certain RPM range that these vibrations occur. I feel a little harshness as the tach climbs to 3K, but then it goes away as it continues to climb to 4 and 5K. There are lots of parts thrashing around under hard acceleration and the combination of them all could give you these vibrations.

That is just like the stupid heat shield rattle. Under certain acell characteristics, my heatshields rattle. I can stop the rattle if I speed up or slow down the engine. In actuality, I think the PF's VQ35 is rough as 6-cyl engines go. Ours is a truck motor and not the same as those in the cars even though it shares the "VQ" part.