The contact owns a 2010 GMC Acadia. The contact stated while driving 45 mph, the vehicle began to idle rapidly and smoke was exiting the hood. The contact stated there was no warning light illuminated. The contact was able to park on the side of the road for approximately an hour before driving to her residence. The contact never saw a fire while examining the vehicle. The contact took the vehicle to an independent mechanic, where it was diagnosed with needing the timing chain to be replaced along with an oil leak. The vehicle was not repaired. A dealer was not contacted. The manufacturer had not been informed of the failure. The failure mileage was approximately 120,000.