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Discussion Starter #1
I started noticing vibrations at around 35mph and RPM around 1100 while steady cruising going downhill and when I try to push on gas gently. Took it to the dealer, tech drove with me but I don't think he noticed much. But tech anyway went ahead and did the tranny drain/refill TSB and applied a software update. Since then, the car has got little bit better but I still have the 1100RMP/35MPH vibrations.

So, what is next? hope it is not a failing transmission. My 2014 MDX is at 52K, so the work was covered under power train warranty.

Also, there is a humming/grinding sound while cruising (usually when foot off the gas pedal). Tech says it is normal, apparently he drove other 2014 MDXs and they had similar issue, so says it is not abnormal.

So, what do I do now?
 

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Well, you could either 1) keep pushing the dealer (maybe go to the service manager) about the persistence of the issue and also that humming/grinding noise (it would bother the crap out of me) or 2) try another dealer or 3) open a case with Acura Client Relations on the basis that the problem still exists and that noise is far from normal for you but the tech believes it is.
 

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We had the same issues. The weird noise was taken care by a TSB, which was done incorrectly the first time and fixed the second time. The transmission was worked a couple of times, the last TSB helped some, but we still hated the transmission we finally traded in for a 2017, love the new 9 speed transmission after the horrible rubber band 2014 transmission. We also had weird suspension noises, which they could never duplicate, imagine that...
 

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Discussion Starter #4
The tranny vibration issue is pretty obvious, I can reproduce it every time I drive my MDX. It is going back to the dealer next Tuesday, will let you know the outcome.
 

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Discussion Starter #5
My dealer shop contacted Acura and my MDX is getting Torque Converter replaced. I am getting back my MDX next week, hope Torque Converter replacement should take care of vibration issue.

I don't see a lot of Torque Converter replacements posted on this site, I am sure there are many others who must have experienced Transmission vibration issues with their 6-speed trannys.

I got a 2018 TLX(V6) as a loaner. It has only 3500 miles on it, surprisingly, even that had vibrations around 1500RPM(I can feel it through steering wheel as well. Also, while driving to work, I pushed on the gas hard and used paddle shifter to down shift... the RPM shot up to 4000 and started swinging back and forth 500-1000 RPM, It continued to do that until I shifted to higher gear using paddle shifter. Whats up with Acura transmission programming?

My 2015 TLX V4 with DCT is soo much better.
 

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Discussion Starter #6
Update...

Torque convertor replaced free of charge by Acura, did it solve the issue?. The original issue was vibrations at exactly 1100 RPM & 35MPH speed, now the same vibrations occur between 1100-1400RPM & between 30-40MPH.

My MDX is going back to the dealer, have an appointment to drive with the technician and show them what I am talking about. I am working on recording the video to support my case.
 

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Is this possibly a VCM problem, and not a transmission problem?
I am thinking the same. I do not know for sure about Gen. 3 models, but earlier models with VCM would not allow the VCM to switch in until the engine got close to operating temperature.

See if your problem exists only after the temperature gauge gets above 1/4 from cold. If so, that may be a clue.
 

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Discussion Starter #10
I am thinking the same. I do not know for sure about Gen. 3 models, but earlier models with VCM would not allow the VCM to switch in until the engine got close to operating temperature.

See if your problem exists only after the temperature gauge gets above 1/4 from cold. If so, that may be a clue.
Yes, the problem exists only after temp reaches normal operating temperature. Also, I am suspecting this vibrations occur when the car fails to down shift from 6th to 5th at 35-40 MPH. I did notice some times it does down shift(RPM jumps to 1500+) and I don't experience vibrations.
Why do you think it is VCM? Isn't the VCM supposed to kick in only at cruising/highway speeds and not at 35-40 MPH?

My MDX has been with the dealer already twice for the same issue, not sure how many more visits :(
 

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i have the same problem, even after the dealer did the transmissin flush, and from what they said they did the software update, right around 37K miles, it worked fine for few months , but the judder came back after few thousand miles, currenltly at 43k, I read there was a new TSB update 16-063, that fixed the issue.
hoping to get the software update soon to see if this will resolve the problem.
i wonder if TSB will be free as i dont have extended warrenty
 

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Not sure when the vcm kicks in, but dropping from 6 to 3 cylinders creates some sort of inherent balance issue or vibration issue (so I've read) that the engine mounts and even the active noise cancelation inside the cabin is supposed to deal with.

So, when. I say VCM, it could be any number of systems related to it, but definitely engine mounts would be a thing to check. I know they're not simple hydraulic mounts like in the old days, but electronically controlled.

Having said that, I would hope that Acura would have ruled them out when investigating this issue and determining that it's a fluid problem.

Having said that, it could be wishful thinking, otherwise TSBs wouldn't exist.. Lol
 

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Discussion Starter #14
Update....

Drove the MDX with technician, I was able to reproduce the issue(vibrations at 35-40 mph). Most importantly, technician felt it sitting in the passenger seat. Tech asked me to stop the car and he disconnected something in the engine bay. I drove the car, this time no vibrations. Tech suggested replacing engine mounts, my MDX is going back to get the mounts replaced probably next week.

So, those who suspected VCM as the issue, you are correct(though I still don't agree why VCM at 35-40 MPH, my be VCM kicks in every time you take the foot off the pedal while in higher gears)

So,
1. Tranny flush & software update did not work.
2. Torque converter replacement did not work
3. Engine mounts - will see what happens

BTW, do you think mounts are bad or something that controls(software?) the mounts requires a fix/update?
Guys, give me some hope.
 

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BTW, do you think mounts are bad or something that controls(software?) the mounts requires a fix/update?
Honda vehicles with VCM tend to be very hard on the motor mounts. It's not uncommon for them to require replacement. I'm curious to hear if that fixes your issue... But I won't be surprised if it does.
 

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Yes, please keep us updated. I did the 3x flush / fill myself and it sort of helped, but not really. Trying to find a day to leave it at the dealer to have the software update done, but not high hopes if the software update didn't help you.

I'm going to disconnect my engine mount(s) and see what happens (but not today when it's -22 out).
 

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Discussion Starter #17
Below is from Acura website..... VCM does kick in at low speeds

"
Variable Cylinder Management™ (VCM®) automatically changes the V-6 engine to run on six or three cylinders, depending on driving conditions, resulting in significantly improved highway fuel efficiency.
During startup, hard acceleration, hill climbing or when high output is required, the engine operates all six cylinders.
At low-speed cruising on city streets, the engine will shut down one cylinder bank (which has three cylinders on one side of the “V”) and operate on the remaining three cylinders.
Active engine mounts improve engine smoothness while the engine is running on three cylinders.
The system monitors throttle position, vehicle speed, engine speed, gear selection and other factors to determine the correct cylinder activation for the operating conditions. The system also monitors catalytic-converter temperature to make sure it remains in the proper range to keep emissions low.
"
 

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There you go... And they make mention of the engine mounts helping. If it turns out to be the engine mounts, I'm mind boggled that Acura hasn't figured it out.
 

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The engine mounts on 3rd-gen have electromagnetic elements that vibrate to cancel engine vibration at the source. When they are working. I have a vibration problem in our 2014, and I’ve been thinking the mounts are suspect.
 

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Discussion Starter #20
Update....

I dropped off my MDX at the dealer shop yesterday to replace motor mounts. Picked up my MDX today(thought they would replace both front & back but they replaced only front), and drove home. Though I drove for less that 30 minutes, I can clearly say that my MDX drives much better now. Though my MDX still exhibits vibrations(which is in line with other V6 TLX loaners I drove), I think I will stop worrying about vibrations for now and start enjoying(?) the ride.

So, anyone feeling vibrations(ignore minor, apparently all Honda V6s with VCM seem to have that) between 1100-1500 RPM and around 35MPH, first get the front engine mounts inspected/replaced. I strongly believe Honda/Acura are downplaying the VCM design flaw and asking the techs to do unnecessary tranny TSBs.

Thanks,
 
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