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  1. 2017 Acadia Vibration at steady speed
    GMC Acadia
    ...a 2017 Acadia that has the problem when the engine goes from V6 to V4. My issue has finally been resolved with Technical Service Bulletin 17-na-168. This bulletin recallibrates the ECM (computer). I had it done yesterday at my dealer and the vibration is gone. To say I am overjoyed is an understatement! ...
 
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Good thing it's the same TSB number. (y)
 

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2020 Acadia, SLE, V6 w/trailering package
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My 2020 (V6 with 1400 miles)has developed a low vibration/rumble when at idle RPM in park or in drive. I will be taking it in because a new car should not sound that way and it is annoying to me. I will have to see if it is in 4 cyl mode when the issue occurs.

I have turned off the AC/defrost and anything else I can think of and the issue persists.
Just a follow up on my post, I took it to the dealer for another issue and asked them about the rumble that I was hearing. They did hear it also but later said it was normal (same as others on the lot). They gave me a 2021 AT4 as a loaner is it had a similar sound at low rpm. So I guess what I was hearing is normal.

That AT4 feels so different (stiffer steering, gas pedal, suspension) than my SLE. The AT4 feels more like a truck and that is not a bad thing.
 

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Ha guys i found if i drive in tow-haul mode it does not go into 4 cyl. mode, not a real fix but works for me,and i read driving in toe-haul mode all the time does not hurt anything. I do realize i will lose gas mileage but that shame is on gmc,at least now i can drive the car without getting mad and twisting the material off the steering wheel HA HA. PS don't get me wrong i am not a 6cyl. nut i would not mind it going into 4cyl. mode for better gas mileage if it didn't vibrate and make that droning sound.Thanks for listening to my rant.
 

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Something must have changed in the 2020 models with the 9 speed. I have no droning sound in our 2019 with the six speed transmission and have to really look at the DIC to see the V4 indicator lit up in order to determine that it IS in 4 cylinder mode.
There is no real noticeable change in sound, no vibrations. . . it motors along just as quiet as in V6 mode.
 

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2020 Acadia, SLE, V6 w/trailering package
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You should not have to drive your brand new Acadia in tow/haul to eliminate any problem you hear.

I am still not convinced the droning/vibration sound on our 2020 is "normal" as the dealer says. if I just raise the RPM slightly it goes away. It just seems to idle too low in park or drive. I did hear something similar on the 2020 AT4 loaner we had but our noise is much worse and annoying. It was not there during the first 800 miles or so, it was very quiet.
Our noise is not related to 4 cyl operation though.

So far with this issue and a few others that have not been resolved I am very disappointed in our Acadia with only 1500 miles. This is my wifes vehicle and I get frustrated every time I drive it. I would trade it in a heartbeat but I don't want to take a beating on the trade in value.
 

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In the last week I have been in 2 different 2021 models and both make an obvious vibration with droning noise. It is better or worse during different conditions but is always there when in V4 mode. Hopefully as time goes by they have a software update to somehow help with this. All 6 Acadia's I have been in now (2020's and 2021's) do this so unfortunately it does appear normal.
 

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My 2020 (V6 with 1400 miles)has developed a low vibration/rumble when at idle RPM in park or in drive. I will be taking it in because a new car should not sound that way and it is annoying to me. I will have to see if it is in 4 cyl mode when the issue occurs.

I have turned off the AC/defrost and anything else I can think of and the issue persists.

Keep us posted if you do take it in and I will do the same (unfortunately it will not be until after Christmas).
We just bought a 2021-GMC Acadia denali with V6. I have yet to see it in V4 and only about 15mpg. It also makes a purring/rumbling noise in park and when idling. Unfortunately I only drove it a few miles before purchasing. I had test driven the AT4 for 3 days prior and thought it would be the same. I was wrong.
 

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The dealer says the low rumble in park and idling is "normal" and the put it on the lift and could not find anything. That type of noise does not sound normal to me. I find myself stepping on the gas when its idling to bring the rpm up slightly to stop the rumble sound. Our V4/V6 mode works and are averaging 20 MPG right now with 2200 miles . The auto stop/start is not working either, dealer had to reset it one time and the other time I took it in when it was not working they could not find a problem with it and it worked for one day after that.

I am starting to think I got a lemon, very disappointed so far and we bought it instead of leasing.

Please post any new info you get on your problem if you find something out.
 

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We just bought a 2021-GMC Acadia denali with V6. I have yet to see it in V4 and only about 15mpg. It also makes a purring/rumbling noise in park and when idling. Unfortunately I only drove it a few miles before purchasing. I had test driven the AT4 for 3 days prior and thought it would be the same. I was wrong.
Goodmorning if you put your instrument cluster to where it is showing instant mpg it will always show weather it is in v6 or v4 mode, in v4 it mode it will highlite in green. I drive mine in toe /haul mode all the time and it never goes into v4 mode. Shame on gmc for not fixing this problem. Let us know how you make out.
 

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Our 2019 Acadia with V6 engine and 6 speed goes into V4 mode quite often and steady speeds and even on some slight grades.
I'm thinking the 9 speed transmission (also depending on trim level) having more gears may not need V4 mode very often.
 

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I've switched the display to watch AFM in action a few times. Disappointed in the way it's programmed. The switch to V4 doesn't happen often enough, IMO. I couldn't care any less, though. I'm getting about 30 mpg on highway trips most times.
 

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Our 2019 Acadia with V6 engine and 5 speed goes into V4 mode quite often and steady speeds and even on some slight grades.
I'm thinking the 9 speed transmission (also depending on trim level) having more gears may not need V4 mode very often.
Ha it would go into v4 mode more often then yours because of the higher gears, it goes into v4 anytime its at a steady spead 50-60 -70-80-klm any time the tack reads about 1500RPM it goes into v4 mode
 

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It does not go into V4 as often as I would expect it to either. Kind of a stupid feature the way it is implemented.
 

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The dealer says the low rumble in park and idling is "normal" and the put it on the lift and could not find anything. That type of noise does not sound normal to me. I find myself stepping on the gas when its idling to bring the rpm up slightly to stop the rumble sound. Our V4/V6 mode works and are averaging 20 MPG right now with 2200 miles . The auto stop/start is not working either, dealer had to reset it one time and the other time I took it in when it was not working they could not find a problem with it and it worked for one day after that.

I am starting to think I got a lemon, very disappointed so far and we bought it instead of leasing.

Please post any new info you get on your problem if you find something out.
Ty I will. Off that you say that about the auto start/stop. I’ve been wondering. Sometimes I’ll stop and the car continues running and sometimes it doesn’t.
Have you noticed thst when slowing down the car feels like it’s automatically gearing down. Or as if someone is tapping the brakes for you? Lol. I’ll be stopping and it’s as if I’m not stopping fast enough and the car will slow me down.
I love the car, but definitely some kinks to figure out. I also have a rattle from the driver side door or mirror that is driving me crazy. It sounds like a piece of paper stuck in the door. I’ve looked all over.
I also have a piece of the DENALI molding that is coming off on passenger side.
I’m thinking $53,000 was very pricey at this point.
 

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Ty I will. Off that you say that about the auto start/stop. I’ve been wondering. Sometimes I’ll stop and the car continues running and sometimes it doesn’t.
Auto stop/start doesn't always shut off the engine at a stop. It's explained in the owners manual.
Have you noticed thst when slowing down the car feels like it’s automatically gearing down. Or as if someone is tapping the brakes for you? Lol. I’ll be stopping and it’s as if I’m not stopping fast enough and the car will slow me down.
The transmission will downshift automatically as you slow down. It's programmed to do that.
 

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With start/stop if you lighten the brake pedal pressure when almost stopped, it won't shut off.
 

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With start/stop if you lighten the brake pedal pressure when almost stopped, it won't shut off.
It won't shut off the engine if there's high electric demand and the alternator is charging the battery or the A/C compressor is running, either.
 
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Our auto stop does not work, I have done all of the research and know what causes it not to operate as you list some of them above. I have a 2020 Sierra and am very familiar with the auto stop/start, it works as it should and i sometimes deactivate it in traffic since it becomes annoying.

My wife drives the Acadia and she said the auto stop/start worked yesterday but is not working again today. This was the first time it worked in 2 months. Its not an outdoor temp issue which I know is another factor in it working. Something is going on with our Acadia when coupled with the low rpm vibration we hear. We also have a rattle in the passenger side dash. This is not what I expect from a new vehicle with less than 2500 miles.

I may try another dealers service department to see if they find anything that my current dealer cannot.
 
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