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Discussion Starter · #1 ·
2017 Acadia Limited AWD has progressively gotten more frequent engine shuttering at low end speeds of roughly 35-45 mph and as of today was in the 60-70 mph range. The issue started about 2-3 months ago. When the gas pedal is depressed the issue stops instantly. The last week or so its beginning to happen more often. I live 30ish miles north of Atlanta so I assume the colder weather is causing the more frequent shuttering. Ive looked around the internet and the throttle body seems to be a place of concern specifically the throttle position sensor. Ive looked in the TB and its really not that dirty. Im thinking/hoping its just a bad sensor. I want to disconnect the battery and check the sensor connection and or clean the connections but hesitant without some input from fellow Acadia owners and those familiar with known issues. I also ran across a post with similar issues but from an older gen of Acadias about reprogramming the PCM or something to that affect.
Any advice and input would be greatly appreciated.
 

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Do you have any mileage and maintenance history to provide along with the problem description? A lot of what you describe could be caused by something as simple as worn out spark plugs, or even a clogged air filter.
 

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Discussion Starter · #3 ·
Do you have any mileage and maintenance history to provide along with the problem description? A lot of what you describe could be caused by something as simple as worn out spark plugs, or even a clogged air filter.
mileage is at 85000ish. Air filter was replaced yesterday but the shuddering is still present.
Would the vehicle not have a problem starting if there were a spark plug issue?
I forgot to mention the RPM likes to fluctuate up and down 100-200 with and sometimes without the shuddering.
 

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...
Would the vehicle not have a problem starting if there were a spark plug issue? ...
Probably not at the temperatures experienced in Georgia if they were equally worn out. There might be some loss of power, or a decrease in fuel economy.
 

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2 Potential Culprits:

1. Check your transmission fluid level per the proper procedure. An over or underfilled transmission can be a source of the torque converter shudder.
2. As you mentioned, I came across the post below where someone replaced their APP (Gas Pedal Assembly). It may not be providing a linear voltage to the computer.

 

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Discussion Starter · #6 ·
Fluid level is adequate. Im wanting to go the cheapest route part wise to identify the problem. Although my concern is eventually I might end up spending what it would've cost to go to a shop but i need my car.
 

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Discussion Starter · #7 ·
A few things Ive left out my apologies ahead of time.
There arent any lights on on the instrument panel. No check engine light, no reduced power, etc.
I filled the tank this past Saturday. Its Tuesday and the vehicle has roughly at most 160/170 miles on it and just above 1/4 tank left. Yesterday morning was at half tank and i might of been a little 100miles into the tank. Absolutely getting terrible mileage.
So far Im considering changing the sparks because its nearing that time anyhow, but the gas pedal assembly makes sense seeing as to how the problem stops all together when depressed. Just not sure where to start. Hopeful a few more inexpensive options are presented. Had to happen around the holidays 🤯
 

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2017 Acadia Limited AWD has progressively gotten more frequent engine shuttering at low end speeds of roughly 35-45 mph and as of today was in the 60-70 mph range. The issue started about 2-3 months ago. When the gas pedal is depressed the issue stops instantly. The last week or so its beginning to happen more often. I live 30ish miles north of Atlanta so I assume the colder weather is causing the more frequent shuttering. Ive looked around the internet and the throttle body seems to be a place of concern specifically the throttle position sensor. Ive looked in the TB and its really not that dirty. Im thinking/hoping its just a bad sensor. I want to disconnect the battery and check the sensor connection and or clean the connections but hesitant without some input from fellow Acadia owners and those familiar with known issues. I also ran across a post with similar issues but from an older gen of Acadias about reprogramming the PCM or something to that affect.
Any advice and input would be greatly appreciated.
Please update if you find the answer. I have been searching all over to find the answer to the same shuttering symptoms on my older 2011( i just got it less than a month ago) so im unsure of the maintenance. no codes during the majority of the time ive had it, my mpg cant get much worse, i could also press through the shuttering and it would straighten out. Mine also has, what maybe you would consider a hard start. It just seems to take a bit longer to crank than you want it to.

Twice in the short time ive had it, i turn the key over and nothing at all happens...So i turn the key back off say a prayer and so far it has started on the second start. Ive check my sparkplugs which is no easy task as my luck would have it. But they looked fairly new. coil packs look new. as does my maf sensor and the tube connecting to the throttle body, they all look brand new. I cleaned the tb,it had some build up but not much. I replaced the air filter it was pretty dirty. Who ever installed it didnt seat it in the box properly so it was crushed on the back side. The new air filter didnt help,Unfortunately. i had a p420 code come up Finally. Researched it most likely cat is done for. Was going to try some cat cleaner but before i was able to today it went into low power mode then died. Crunk once or twice but would barley move, i was able to get out of the intersection i was blocking but thats as far as i made it. Battery died out pretty quickly from me trying to crank it. I live about 30 miles west of atl also,i dont think its weather related for either of us.

Ive also replaced the crank positioning sensor, i wouldnt say it helped any thing...i have a shitty third party warranty that i now see is pretty much a scam. Sounds comforting when you buy a car like i did but doesnt cover much. Lesson learned! i have access to a good scanner where i can see dtcs and there were a few fault codes but in other systems like hvac and the key transponder nothing related to this problem. Anyone who takes the time to read my long comment that can tell me anything i could look at with the scanner or at the live data would be greatly appricated. Other than what ive googled im clueless.

with the p420 it could be o2sensor, most likely bad cats. But with my low power mode today, im gonna cross my fingers its o2 cause it is more in my budget than cats. Good luck, ill report back also with anything i find out tomorrow. if o2 doesnt need replaced guess ill call a mechanic
 

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Discussion Starter · #9 ·
Ill share the info when it becomes available. I dont mind the diy mechanical stuff but remain hesitant on due to the anxious mindset on the issue and almost accidentally break stuff. Im hoping to have the issue resolved before the end of the year.
 

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You may want to look here, I have a shuddering also but to me it seems like a transmission problem.https://www.carproblemzoo.com/gmc/acadia/2012/ usually the torque converter or the wave plate.
 

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mileage is at 85000ish. Air filter was replaced yesterday but the shuddering is still present.
Would the vehicle not have a problem starting if there were a spark plug issue?
I forgot to mention the RPM likes to fluctuate up and down 100-200 with and sometimes without the shuddering.
I had the same issue with my 2017 SLT 3. Engine shutter at low speed, light throttle, along with RPM fluctuation. The transmission solenoid unit went bad and the transmission had to be replaced. $3300. When you take it to the dealer have them check the transmission shift solenoids. The check engine light will not come on for the solenoid failure until it’s too late. Sorry to be the bearer of bad news just wanted to give you a heads up.
 

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Cant seem to find the part on search engines anywhere. Sorry i haven't had time to look around on here before posting. Spark plugs changed but problem persists. Shuddering, terrible gas mileage, sluggish, now the sound of rolling over an interstate rumble strip has been occurring the past few days.

any thoughts on possible vacuum leak somewhere?

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I had the same issue with my 2017 SLT 3. Engine shutter at low speed, light throttle, along with RPM fluctuation. The transmission solenoid unit went bad and the transmission had to be replaced. $3300. When you take it to the dealer have them check the transmission shift solenoids. The check engine light will not come on for the solenoid failure until it’s too late. Sorry to be the bearer of bad news just wanted to give you a heads up.
Not to pile on, but this is definitely a TECHM failure. I have a 2016 AWD Denali that initially had the torque converter RPM fluttering, and after $800 to replace the TC, the TECHM shutter began and have been driving with it for over a year at this point (never had a trouble code). I'm not sure if this will eventually ruin the TC but I figured at some point I will be forced to replace the entire transmission. Use this website for what I've found as the best deal for our trannys: Remanufactured Transmissions Factory Direct | Street Smart® Transmission
 

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Cant seem to find the part on search engines anywhere. Sorry i haven't had time to look around on here before posting. Spark plugs changed but problem persists. Shuddering, terrible gas mileage, sluggish, now the sound of rolling over an interstate rumble strip has been occurring the past few days.

any thoughts on possible vacuum leak somewhere?
That part is readily available on Amazon.
 

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Discussion Starter · #19 ·
🤯
Well. The issue(s) im currently having are gradually worsening. Scheduled to drop off at dealer this weekend. The more i think about it the more im thinking its a fuel filter/pump problem. Sparks were changed, no luck, broke the purge valve in process the new valve didnt help tho. Im hearing a random rumble strip noise that only persists when foots on the gas. When depressed the shuddering, the noise all stop. The noise is coming from what sounds like the center of vehicle and to my knowledge as of recently ive read the fuel filter is in the gas tank. That extends up to under the front seats upon inspection. The bad gas mileage, shuddering at certain speeds and up a hill, and the noise are making me think its fuel filter/ pump related. By no means am i a mechanic but instinct and some common sense 🤷🏻‍♂️
Praying its not the transmission. That fluid is good and no codes have been thrown, no christmas dadhboard no nothing. Bad mileage, shuddering, and a rumble strip noise thats becoming more frequent.
 

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... The more i think about it the more im thinking its a fuel filter/pump problem. ...
The fuel filter is nothing more than a fine-mesh sock attached to the fuel pump's inlet. It's an integral part of the fuel pump assembly. Maybe it somehow got partially blocked from a load of dirty fuel. If that's the case, you're looking at a whole new pump assembly.

Fuel now gets filtered at the dispenser. That's why many makes only have some kind of 'final filtration' at the fuel pump and not a separate removable filter. The service station may have neglected its dispenser maintenance if the fuel had too much 'dirt' in it.
 
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