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Hi

Have a 2012 Traverse LTZ with 108k miles.

Lately it has started going up and down in RPMs by itself when driving, but only when the engine is around 1600-1800 RPM.
At higher RPMs it seems stable and it’s mostly noticeable when driving slow in lower gears but is still noticeable even at highway speed.
If I speed up to > 2000 RPM, the issue goes away.

At the same time it has started to vibrate and kind of stutter when gearing down while going uphill, again when around 1600-1800 RPM and most noticeable when doing slow in low gears. It feels like it’s not sure about when to change gear and kind of messes up the gear change, hence the vibration.

Finally I have seen 3 misfires (P0305 and P0300) and a Vacuum Sensor A/B Correlation (C0561) event.
When these happened it disabled traction control and lit check engine light.

Have already tried disconnecting battery for 5 min. No change.
Have drained and refilled transmission oil. No change.

Thinking about replacing spark plugs, coils and maybe throttle body and eventually TECHM/TCM, but wanted to hear here if anyone have an idea about root cause ?

/Jesper
 

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being that its 108,000 miles.
Run several bottles of Techron Concentrate PLUS- over several tank fulls.
Also change the plugs and clean the throttle body.
Im wondering if youve cleaned the oil in the tube-- and maybe it has gotten to your air filter and dirtied it.
Id also clean the MAF

The TECHM- Id probably do last depending on the results of the above
 

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Do you have anything plugged into the OBD port at all times?
 

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At 108K I'd definitely do the plugs and if planning to keep for the long term, might as well do the coils too just to rule them out and as preventative maintenance.
 

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I'd start with the throttle body -- clean it thoroughly; and if you've never cleaned it then also replace the MAF as well. If there's enough oil in the tube, it can propagate backward and contaminate the MAF.
 

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I started having similar issues around the 110k area. I'm also getting the banging sound when shifting from P to D, usually first thing in the morning. Plus there's a rattling/grinding noise coming from the rear underside of the vehicle as well. I fear its the tranny going up.

I've done all the usual fixes here lately. New plugs, new air filter, cleaned the throttle body and MAFS. I'm not saying yours is the Trans but keep that in the back of your mind.

Kev
 

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Based on the symptoms it sounds like the crankshaft position sensor is failing. This sensor tells the computer when the engine crankshaft has the cylinders at top dead center to get the timing right for sending fuel in and firing the spark plug.



Not an unusual problem and not terribly expensive (under $300 in total) to have the sensor replaced.


When it fails completely the vehicle will not be driveable at all so best not to wait to have this fixed.
 

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I am also having this issue. No codes. I keep wondering if the fuel pump is beginning to fail or if there is a cat starting to clog or is underperforming causing back pressure to engine. I've replaced fuel injectors, throttle body, MAF, plugs, wires, coils, intake manifold air cleaner tube, battery, hoses, ECM/pcm and o2 sensors. When I am trying to maintain a constant speed of any level wether on highway or not the RPM needle dances up and down a great deal non stop until I either give it more gas or let off completely. The GM dealer says the car is fine bc there are no codes but they also haven't test drove it to recreate the problem and won't help me diagnose the issue. I just had to cancel a trip for work across the country because the vehicle is doing this at an extreme level. I can feel the rpm surges up and down in the engine like hesitation when rpm goes down and surging when it goes up so it makes the vehicle seem like it's starving for gas/air or power. But with no codes and after all the parts having been replaced I just don't know where to go from here.. could the crankshaft position sensor be starting to fail and hasn't thrown a code yet? Any help would be greatly appreciated as I can not find anyone that is able to point me in the right direction. Thanks.
 

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Did anyone get a definitive answer on what this is and how to fix it? I have the exact same symptoms as original poster (Jesper) so did not want to start a new thread with the exact same description. I have done plugs, MAF replacement, throttle body cleaning, new air filter, PCV valve. I change the transmission fluid every 30k miles and am in mid cycle of that timeline. Vehicle runs great otherwise.

Anyone changed the crankshaft position sensor and this went away? Feels to me like fuel pump or fuel delivery or something related to air/fuel delivery as the RPM flux is generally at lower RPM (1300-2000) and when you get on the gas it does not happen. Just does not feel tranny related to me but I cannot find anything definitive anyone has found that fixes this.

Advice appreciated
 

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Same issue here. it is mostly between 13-1800 rpm, if I give it a little gas it runs great. Mine has been this way for 2 years, and it does seem to have gotten worse. Some day I will be on the side of the road... Someone said it was trans, and I have done 3 trans flushes, replaced the throttle body, not plugs tho. I'm at 136k miles. Hopefully someone finds the fix
 

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Same basic issue with mine.
I have been reading all over the net, and hope I can get some help here.
I know there are dozens of posts covering this problem, and have read quite a few of them already, so please excuse me if this seems to be a redundant post.
We own a Traverse AWD LTZ with a 3.5, which is a great vehicle and in excellent condition, especially for the high mileage, but has developed two main issues, a shudder when under a LIGHT load, which stops if you give it more gas, and rpms often bobbing around 200-300 rpms. It also throws an emission code. Shudder started only at highway speeds, but is now apparent at almost any speed. If the car sits a few days, it isn't nearly as bad as when you drive it a few days straight. RPM fluctuations started awhile after the shuddering started. Also, gas mileage seems to have gone down as well.
I have seen dozens of 'attempted' fixes, which usually stop the problem for a short space of time, but most of the time it comes back.
I have other cars to drive, and with warm weather almost here, I want to FIX this problem, one way or another.
If that means I have to put in a new timing chain, sensors, bearings, etc, so be it. I have all the tools and do almost all my own work, but need to know where to START. I have seen DOZENS of attempted fixes, yet no real 'fix'.
I would appreciate any and all help here, with the most likely problems and the cheapest fixes first.
While I am not ready to replace the entire drivetrain, I am not afraid to spend a couple thousand if that will actually fix this car. Crankshaft position sensor, , plugs, MAF, plugs, coils.....where best to start?
Thanks to everyone in advance!
 

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A good scan tool is the first place to start. One that will read all 4 code families of P, C, U and B not just basic P codes and has test functions in it.
Shop manual is next. I use alldatadiy.com for my fleet.
I say this as I chased a 3-mpg loss in my Tahoe along with emissions monitors not being ready for state inspection.
No P codes or any other codes where being set or appearing.
My Autoenginuity scan tool has 2 MAP sensor tests in it, mine was erratically failing one of the 2 tests. Great scan tool to the rescue. That's why I strongly recommend having a good scan tool if you are doing your own repairs.
Either you have one or pay someone to use theirs as a cheapo one scan tool doesn't cut it on the difficult diagnosis jobs.
You're at the level of looking at fuel trims both short and long among other readings.
 

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I have the same RMP fluctuation problem in my 2012 Traverse LTZ w/ about 156,000 miles. Like others I've not really started down the rabbit hole of trying various things to fix it. Will be watching the page for possible final resolutions.
 

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I too have just joined this "club". For mine this has been extremely intermittent. Maybe once per week. The lurching is extreme and I'm pretty sure it's the transmission. I have no set or pending codes and ignition is smooth. It did this today and this is what I did:
It started bucking as I was slowing down for a traffic backup. I shifted into L6--no change.
I turned off traction control--no change.
At this point the rpm surging between ~ 1000-2000 stopped and went low (deceleration). I responded with lots more throttle but it continued to slow. More throttle till I look at the tach and see it's holding SOLID at 4000rpm even as the vehicle is slowing.

Really feels like major trans slippage. It's curious that the ECM seemed to be maintaining the 4k rpm in response to my matting the pedal.
The only time I've seen that before was another make/model I was trying to hit the Rev limiter while in Park and the ECM responded the same way--held it solid and smooth at 4k. NOT bouncing off the limiter.

Do you all concur that this behavior is transmission and NOT engine?
 
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