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Discussion Starter · #1 ·
Hello Everyone,
We have had our 2009 Acadia SLE fwd for 1 month now and it has 2100km or about 1200miles on it and it has started to surge or rev up when slowing down, it seems when coming to a stop from 40 km to 0km the engine rpm will slowly drop as normal with foot off the accelerator, as speedo nears 10km to 0 the RPM will drop to around 800rpm and than jump to 1200-1400rpm and than drop and hold at 600rpm when fully stopped. Have noticed this will happen with foot on and off the brake pedal. Brought to the local dealer and they had it for 1 day and say there are no codes so nothing is wrong, this does not seem normal as I have never had a car or truck that with your foot off of the accelerator and while braking or not will accelerate on its own. Anyone else have similar issues ?
Overall though so far pretty happy with the truck, just was hoping for better mileage with the 6spd tranny, if compared to my 2002 Envoy both at 120Km will turn 2000RPM, would have expected the Acadia to turn 1500-1600 rpm with a 6psd as the Envoy has a 4 spd.
Thanks
 

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Not sure if this is the issue but the tranny will downshift on downward inclines in an effort to control braking and speed. This is normal.
 

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Discussion Starter · #3 ·
It is happening on flat roads, no inclines or declines, it feels as if it wants to pull forward, I could understand what you are saying on a decline, much like a manual tranny if you gear down the Rpm will go up, other GM Trucks I have had never did this unless manually dropping the tranny from 4 to 3 to 2 and so on, but never when left in OD top gear and it slows down on its own. Or is this the NEW TECHNOLOGY of the tranny trying to keep the RPMS up for when it is go time so it does not have to run through the full shift pattern ?
Sorry but as said I have driven GM Manuals and Autos for many years and this is a first for me with an Auto, have logged many whiles with GM Auto Trannies and all have been Great, this just has me a little worried for when the wife drives it as she has a light foot on the brake pedal and would not want it to take off on her and she rear ends another car !!!
 

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The tranny is programmed on declines to downshift to help to slow down the vehicle, I don't think this is your issue from what you've explained. It's tough to diagnose issues without being there first person to see what the problem is.
 

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Sounds like you need to get it serviced. While many owners have found the Acadia transmission annoying, I have found no issues with it at all and it seems to be quite dependable. And if not, it's covered for 100K miles so no worries.
 

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mikemu said:
Sounds like you need to get it serviced. While many owners have found the Acadia transmission annoying, I have found no issues with it at all and it seems to be quite dependable. And if not, it's covered for 100K miles so no worries.
Same here; the trans is dependable, but the reprogramming seems to extend the shift points
 

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i noticed this several times during my roadtrip but its on when i am downhill, and its normal. did the dealer tried to replicate the problem and did not find the problem?

your mileage will be better. i averaged 11.7L/KM during my 2500 KM roadtrip 2 weeks ago. :thumb: Welcome to the forum :cheers:
 

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Discussion Starter · #8 ·
Thanks for the Welcome !!
Yes I took the tech for a drive and told him to watch the Tach, it was repliacted 4 times with me in the car, he said yah I see it how the Tach goes up 600-800 rpm, we than drove back to the dealership and they had the truck for the rest of the day. By their addmission they said it was hooked up to the computer to check codes, non found so they gave it back, seems to me unless the magic box tells them where to look, they have no clue what they are doing, obviously not old school mechanics that knew what parts did what in a vehicle. Oh well it is covered for 5 yrs 100,000 km, guess will drive it and see, there is a record at the dealer to the complaint so they cant say I did not bring it to their attention.
 

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cdnacadia said:
...unless the magic box tells them where to look, they have no clue what they are doing, obviously not old school mechanics that knew what parts did what in a vehicle...
That is a problem with "technicians" as opposed to purist mechanics with great technical aptitude. I can't understand why the tech would send you down the road without a full discussion between him and the service manager while you were still there. It sounds like something folks higher in the GM engineering 'food chain' should know about.
 

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RE: Engine Surge
I just expierenced a surge on my 2008 GMC Acadia and it acclerated suddenly with my foot on the brake and we hit the right rear quarter panal of the car in front of us. We were on a slight incline. In trying to duplicate the issue, I found that if the brake was applied with just enough force to prevent movement to the vehicle, and RPM at 700, with just a little increase in RPM to 1400 to 1800 RPM, the car will lurch before the brake can be applied further with enough force to stop the vehicle. I sware my foot was on the brake when the car suddenly acclerated and lurched with enough force to cause damage to the car infront of me. Movement about 3 feet total.
I was unable to get the engine to suddenly acclerate on its own.
 

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I just had this happen in my 2015 Acadia. Scared the crap out of me as I was waiting for people to cross in a cross walk in front of me. I had the brakes pegged down, and the engine just kept revving. When the people were safely passed I let my foot of the brake a little and she peeled out. When I stomped my foot back on the brake it stopped. Now I'm afraid to drive her as it happened at work in a large parking lot. What if I can't stop her next time.
 

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Hello and welcome.
Sorry to hear of your certainly scary issue! Hopefully you can get it to a shop to see if any "codes" are present in the car PCM. Or. . maybe take it to a automotive parts store where thyey often will read any potential codes for free.
 

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I just had this happen in my 2015 Acadia. Scared the crap out of me as I was waiting for people to cross in a cross walk in front of me. I had the brakes pegged down, and the engine just kept revving. When the people were safely passed I let my foot of the brake a little and she peeled out. When I stomped my foot back on the brake it stopped. Now I'm afraid to drive her as it happened at work in a large parking lot. What if I can't stop her next time.
Could be the accelerator pedal's return mechanism is sticky. When that happens in a parking lot, stop the vehicle, lift on the pedal (could do it with your toe), and see if the engine returns to normal idle. Doubtful if that type of failure would set any trouble code.
 

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Hello and welcome.
Sorry to hear of your certainly scary issue! Hopefully you can get it to a shop to see if any "codes" are present in the car PCM. Or. . maybe take it to a automotive parts store where thyey often will read any potential codes for free.
Thanks! That's my plan. Nothing like being afraid to drive... Nightmares of Christine ??
 

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Thanks! That's my plan. Nothing like being afraid to drive... Nightmares of Christine ??
LOL . . . yeah the demon car.
Pending codes can be logged in the ECM even if a CEL light is not illuminated. So a OBD II scan may or may not reveal something.
There is always a chance the gas pedal sensor or even throttle body may have some malfunction or hang up too.
 
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