Idles rough while stopped in traffic or running in park. Desieling after shut off. Took to dealership and told them about dieseling. They checked for chain stretch and fuel pump and said they were fine.

Update from Apr 3, 2015: Car now 9 days out of warranty, as of yesterday. Rough Idle, dieseling,continue and have to feed with gas at stop lights. Now engine light on. They found no problem in Terrell County dealership when this problem originally occurred, I was told. Said that the timing chain was O.K. I told them that the car was not O.K.!

Now the dealer in Augusta is talking about replacing the timing chain and looking into the engine light problem.

I am working with dealer in Augusta now, but am so unhappy and alarmed. Why does this company seem to delay repairing their known, ongoing problems until the coverage is out of warranty. I only have 42,600 miles on this expensive vehicle.

First off, I LOVE my Terrain. This is literally the first problem I've had with it, so don't take this as a reason to totally shy away from them.

My car starting to idle really slowly (about 500 RPM) and was also running really rough. The idling at one point got so low the car actually thought it had shut off, and reset the dash lights (as if the car had just been turned on). The car would also "diesel" when turning off (the engine would chug so to speak for 10 seconds after the key was off sounding something like a lawn mower.) The check engine light came on so I scurried to a dealership to have it checked out under GM Certified Pre-Owned warranty. They plugged it in and decided that it was plugged fuel injectors. They cleaned them out and sent me on my way. Weeeeeelllll that lasted about 10 miles. It was still running rough but I gave it some time and thought maybe they were just still cleaning out. I gave it 3 days of light short driving, and decided that it was not going away. Took it to another dealer and they sent me away since I didn't have a light on. Came back with light on and they told me that the light that was on shouldn't have been causing the low idle, rough running. They at that point didn't feel it was the injectors either. They took a shot in the dark and replaced the High pressure fuel pump, which after about 45 miles of driving it seems to be doing the trick. It still idles low in Eco mode, with no rough idle though, and I assume it's always been somewhat low (650 RPM as opposed to a normal 700-800RPM) because Eco is geared a little differently. But as of now no issues at all outside of Eco mode. I am also using 91 octane premium gas in it now, as opposed to 87 octane mid grade, hoping that helps the problem from occurring again. Plus, the better gas mileage and extra power don't hurt :) The car does highly recommend 87 octane or better. I'd recommend that for sure just to get the better gas mileage.

What I as someone looking to buy this car would look for is idling low at stoplights, and rough idle after long periods of time running while sitting still. I think this was just a fluke, maybe from my car being a fleet rental car before I owned it? I don't know, but I still have a ton of faith in my car even after this. The warranty saved the day though money wise.