I bought a 2012 Buick Enclave about a month or two ago and within a week or so the SUV started missing or shuttering. I felt it needed a tune up. I called my mechanic and ask him to look at it explaining to him what was happening . he called a few hours later and said the valve cover gasket was leaking and oil was getting on the spark plugs. ok do the fix. well $642.00 later no fix!! I was pissed to say the least.

I took matter on myself and cleaned the throttle body but still the car did not stop the shuttering at low speeds. The car while cruising around 55 or 65 mph the rpm would start fluctuating up and down. New spark plug and ignition coils and still the problem remains. I decided to talk to a mechanic at the local dealer and he looked on the computer and questioned he transmission guy. He re-tuned telling me that this was normal for this type engine and GMC said for its dealers not the do anything.

The dealer also said this was happening the a lot of cars that have this type of engine and transmission. GMC needs to fix this problem with a recall.

Driving down the highway with the cruise control on, all of a sudden my speedometer drops from 65 mph to 20 and then back up to 65. At first i thought i hit a button or something so i just put cruise control back on kept singing to the music. about 10 minutes later it happened again. So i kept cruise control off and kept going. about 15 minutes later a Traction control off message came on the screen and the icon blinked. 30 seconds later a service stabilitrak message came on, then the dreaded "check engine" icon lit and stayed on. After taking it to the dealership, the diagnostic message had something to do with the transmission module. That was fixed and light was off, but the problem still happened. My vehicle has been to the dealership 3 times since and has not been solved. After doing some research, I found that others with the same problem said the timing chain needed to be changed to fix the issue. I will take the car back and see if that fixes the issue.