Yep I had a mech time me driving and the gear shift seems like 2to 3 rd was .06 of a sec and 3 to 4 th ( around 40mph) was sometimes as high as .08 but I did notice I’m low on fluid where’d it go I dunno, but I’m getting the same answer you are seems like the plates aren’t locking up and the shudder we feel is when it’s trying to Grab hold to change gears ,
3.6L LLT RPM jumping, engine surging, poor gas milage
I’ve seen posts similar to this issue I’m experiencing but wanted to throw out my experience. It started with noticing my car feeling like it was jumping slightly while in cruise or sometimes when I’m pressing the Accelerator. I recently noticed my RPM bouncing up and down very noticeable when in cruise or any other time really. Gas Mileage is horrible now as well. Got the oil changed and put fuel injector cleaner and it seemed to act better but soon (a few days of driving) symptoms returned.
Took it to a state park with many steep hills with a speed limit of 15 and at two points when going up the steepest it felt like it was going to choke out and die but I gassed it and it went away. I drive it daily in home health and noticed it getting worse with the engine jerking a couple of days ago it felt like I was driving on a cobblestone road when trying to accelerate onto the highway but after pressing gas harder it stopped. took it to the mechanic not throwing any codes.
Took it to a state park with many steep hills with a speed limit of 15 and at two points when going up the steepest it felt like it was going to choke out and die but I gassed it and it went away. I drive it daily in home health and noticed it getting worse with the engine jerking a couple of days ago it felt like I was driving on a cobblestone road when trying to accelerate onto the highway but after pressing gas harder it stopped. took it to the mechanic not throwing any codes.
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This is 100% the transmission solenoid computer. I took our 2017 Acadia in with a jumping tachometer and surging at hwy speeds with no dummy light on and told them I felt like it was computer related. They called in a GMC engineer and he hooked up a computer from the factory and it threw some codes. He reset it and there have been no issues since. It's not spark plugs, coils, or carbon build up its the solenoid computer.Had the wave plate issue at 116,000 miles on my 2010 Outlook. Tranny was rebuilt and everything was fine for about 2,000 miles. Started acting like previous owners said ie... speedo jumping, tach reading erratic due to tranny shifting up and down and poor mileage. Shop checked it out and determined that a bad torque converter was at fault. Fixed under the tranny warranty free. Was still working fine when the timing chains failed at 223,000. Bought new Acadia Limited to replace it.
I have a 2014 arcadia, loved it, but having similar issues. Feels like its choking, or bogging down when accelerating, similar events when driving press the gas pedal to the floor to stop it, or smooth out the shaking . one trick i noticed under the steering column i moved some wires and it started to drive alot better. The gas millage is around 8 to 11 miles if on the freeway or going around town, town sometimes 3-5 miles. I also took it in but its not throwing a code so they told me its all good. does this sound close to your issue?.I’ve seen posts similar to this issue I’m experiencing but wanted to throw out my experience. It started with noticing my car feeling like it was jumping slightly while in cruise or sometimes when I’m pressing the Accelerator. I recently notice my RPM bouncing up and down very noticeable when in cruise or any other time really. Gas Milage is horrible now as well. Got the oil changed and put fuel injector cleaner and it seemed to act better but soon (few days of driving) symptoms returned. Took it to a state park with many steep hills with speed limit of 15 and at two points when going up the steepest it felt like it was going to choke out and die but I gassed it and it went away. I drive it daily in home health and noticed it getting worse with the engine jerking couple days ago it felt like I was driving on a cobble stone road when trying to accelerate onto the highway but after pressing gas harder it stopped. took it to mechanic not throwing any codes.
2012 SLT2 with 134k, original owner, motor & transmission. Experiencing similar issues. (bouncing RPM and occasional vibration during acceleration).
Came across a post of someone who had replaced transmission & torque converter but problem re-appeared so I'm not going to jump into getting a new transmission & torque converter just yet.
First step I'm taking is to replace the battery. Low voltage can make the Transmission Control Module not behave correctly. Seems a bit weak in starting and has 40k miles & 2-1/2 years on it. Still under warranty. I had a previous non GM vehicle that started having transmission issues due to a weak battery. Replaced the battery and the problems were gone.
I'll report back when I have new information.
Came across a post of someone who had replaced transmission & torque converter but problem re-appeared so I'm not going to jump into getting a new transmission & torque converter just yet.
First step I'm taking is to replace the battery. Low voltage can make the Transmission Control Module not behave correctly. Seems a bit weak in starting and has 40k miles & 2-1/2 years on it. Still under warranty. I had a previous non GM vehicle that started having transmission issues due to a weak battery. Replaced the battery and the problems were gone.
I'll report back when I have new information.
Any luck with solution? Mine does the surging randomly under light acceleration as well. Already replaced coils, plugs, intake manifold gasket, map, maf, O2 sensors, knock sensors. (Most of this was done to address a misfire, but helped uncover the surging now)
Have run compression check and leak down and everything looks great. I am thinking it may be timing chains or the camshaft actuators not functioning properly. I don't believe it is a transmission issue but could be wrong.
Have run compression check and leak down and everything looks great. I am thinking it may be timing chains or the camshaft actuators not functioning properly. I don't believe it is a transmission issue but could be wrong.
Whew, you did a lot. Thank you. That's good information to know.Any luck with solution? Mine does the surging randomly under light acceleration as well. Already replaced coils, plugs, intake manifold gasket, map, maf, O2 sensors, knock sensors. (Most of this was done to address a misfire, but helped uncover the surging now)
Have run compression check and leak down and everything looks great. I am thinking it may be timing chains or the camshaft actuators not functioning properly. I don't believe it is a transmission issue but could be wrong.
I took it to a reputable transmission shop for a test drive. They believed it was the torque converter but said the clutch pack (wave plates) don't last forever, either the TCM, and it just doesn't make sense just to replace individual components with the labor involved to drop the transmission, one with 134k miles on it. I totally agree. They quoted about $4k for a reman transmission with a 18mo/18k warranty.
While I respect their expertise, I also realize their financial interest in the recommendation.
I may take it in to a GMC dealership to get their analysis and recommendation. I'm sure they have had enough of them come thru to know what needs to be done. Doesn't hurt to get a second opinion.
I also noticed there is a slight bump when shifting from Park into Drive. My first thought was worn CV joints but I don't experience any other issues with them. Hence, another sign pointing to the torque converter.
I still plan on replacing the battery but will wait until closer to Winter at the end of the battery warranty period. The vehicle otherwise continues to drive/shift smoothly under all other conditions. I've adjusted my driving style to try to avoid the rpm fluctuations and bump on light acceleration as much as possible.
I was looking at engine and noticed I have a really bad front motor mount. The engine is rotating alot under load. I am going to replace it this weekend should fix the thump I started getting recently. I am also going to test the accelerator position pedal and throttle body to see if I am getting a steady signal throughout the range.
Great ideas and potential sources of the bump out of Park. Let us know what you find out.I was looking at engine and noticed I have a really bad front motor mount. The engine is rotating alot under load. I am going to replace it this weekend should fix the thump I started getting recently. I am also going to test the accelerator position pedal and throttle body to see if I am getting a steady signal throughout the range.
Curious how you're able to see the engine rotation under load?
This takes 2 people to do..Curious how you're able to see the engine rotation under load?
Open the hood, have someone start the vehicle. Apply the brakes and put it in drive.
You should see the motor move up. If it doesn't, keep applying the brake and give it some gas.
This is how I found mine were broke on our traverse. Also the torque strut rod was broke/wore out as well.
Hope this works
Thank you. I misinterpreted the previous comment and was thinking how they were checking the engine load while the vehicle was in motion.This takes 2 people to do..
Open the hood, have someone start the vehicle. Apply the brakes and put it in drive.
You should see the motor move up. If it doesn't, keep applying the brake and give it some gas.
This is how I found mine were broke on our traverse. Also the torque strut rod was broke/wore out as well.
Hope this works
I'll check mine when I do my next oil change. Will be changing the front rotors, pads as well.
Please be sure to stand off to one side when you do that and not directly in front of the vehicle. Better safe than sorry, as they say.I'll check mine when I do my next oil change.
Thank You. Agreed and was the plan but very important to point out. Would not be fun getting pinned up against a garage wall....Please be sure to stand off to one side when you do that and not directly in front of the vehicle. Better safe than sorry, as they say.
Murphy can show up with that law book almost any time. I've seen things happen that would stand anyone's hair on end - most with minor injuries or property damage and bruised egos, TG.Thank You. Agreed and was the plan but very important to point out. Would not be fun getting pinned up against a garage wall....
Remember to check in forward and reverse same way as outlined above. In drive you will be checking the front mount and the rear mount when you are in reverse.
You can also easily check the trans mount using same method (you can also apply a pry bar to it). It is located and easy to view by turning steering wheel all the way to the left then lifting the flap at the back of the wheel well toward the front.
You can also easily check the trans mount using same method (you can also apply a pry bar to it). It is located and easy to view by turning steering wheel all the way to the left then lifting the flap at the back of the wheel well toward the front.
Came across this discussion as well as a potential cause/solution to the issue(s):
www.acadiaforum.net
Hesitation & jerky between 1000-2200 rpms
I have visited the dealer 3x. I have a 2012 Acadia with 86,000 miles. The car is hesitating and jerks when applying,releasing and reapplying the gas while the car is running at 1000-2200 rpms. The car never puts out error codes and the dealer can't duplicate the problem. It happens consistently...
www.acadiaforum.net
I had the surging hesitation and it seems to be gone now (I have only driven a couple times though).
What I did was two fold I drained trans and refilled and added 2 containers of Shudder fix, then I replaced the accelerator position sensor (even though I had no cel for it). It seems to be gone and the APP was the most noticeable.
Hope it doesnt come back but happy for now.
What I did was two fold I drained trans and refilled and added 2 containers of Shudder fix, then I replaced the accelerator position sensor (even though I had no cel for it). It seems to be gone and the APP was the most noticeable.
Hope it doesnt come back but happy for now.
Thanks for the information. What made you decide to change the accelerator position sensor? What does APP stand for?I had the surging hesitation and it seems to be gone now (I have only driven a couple times though).
What I did was two fold I drained trans and refilled and added 2 containers of Shudder fix, then I replaced the accelerator position sensor (even though I had no cel for it). It seems to be gone and the APP was the most noticeable.
Hope it doesnt come back but happy for now.
It is essentially the pedal side of the drive by wire system that activates the throttle body. It seems to me that I got the worst surging when I held the pedal steady at very low load, light acceleration. I could have tested the APP to see if I was getting a smooth arch but I decided to just spend the $30 and install a new one. Seems to have helped just as much or more than the Shudder fix.Thanks for the information. What made you decide to change the accelerator position sensor? What does APP stand for?
That's great to hear. I experience the same symptoms. Can you reference the part number for the APP? Was it AC Delco or a 3rd party? The vehicle has 135k on it so I'll replace that first and see if that solves it.It is essentially the pedal side of the drive by wire system that activates the throttle body. It seems to me that I got the worst surging when I held the pedal steady at very low load, light acceleration. I could have tested the APP to see if I was getting a smooth arch but I decided to just spend the $30 and install a new one. Seems to have helped just as much or more than the Shudder fix.
84024926 GM part. Also when you do it be sure and pull the ECM and TCM fuse for 20-30 min to force a relearn of the throttle body.
GM Genuine Parts 84024926 Accelerator Pedal
They had a used one in new condition and I only paid $30 for it.
GM Genuine Parts 84024926 Accelerator Pedal
They had a used one in new condition and I only paid $30 for it.
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