2018 Buick Enclave extremely loud transmission or engine rumbling/booming noise problem resonating throughout the cabin while the vehicle is idling in drive with the AC on with foot on brake. Does anyone know what the issue is? The noise will go away immediately when foot is off brake pedal or when shifted into park or neutral. Usually will happen on a hot day in stop and go driving with the engine rpm elevated to 900 rpm, if engine rpm is below or more than 900 rpm there’s no rumbling/booming noise coming from under the hood. You have to have headphones or speakers with bass to be able to hear the sound I’m talking about.