Hello,
This could be a case of your vehicle just sounding louder when it's operating in Open Loop operation. When your vehicle first starts up the Power-train Control Module [PCM] or "computer" can't get all of the information that it normally gets from the input sensors because the vehicle hasn't yet reached it's normal operating temperature. So it reads the required information it needs to work from a pre programmed fuel injection and ignition table. When the PCM does this is called Open Loop operation. It usually lasts for a couple of minutes until the Engine Coolant Temperature[ECT] and, more importantly, the front O2 Sensor[s] [HO21S1][s] get up to temperature. After this, the PCM then gets all the required information from the input sensors to operate and adjust the fuel injection and ignition tables as engine conditions dictate. This is known as Closed Loop operation. Since Open Loop operation is not as efficient as Closed Loop operation, your vehicle may just sound louder, and there should be nothing to worry about.
Thanks,
Alex
2CarPros
Nov 24, 2019 at 8:45 PM
