A chugging or choking sound can be caused by a blockage in the exhaust system, such as a bent pipe or plugged catalytic converter. Rattling noises can be caused by a misaligned exhaust system that is touching something under the car, or by a loose baffle in the muffler or resonator. Rattling noises can also be caused by a catalyst that has broken apart internally and is loose in the system or has worked its way back to the muffler. A loud metallic vibration usually indicates something is touching the exhaust pipe, or a clamp or hanger is loose. A more muffled metallic vibration coming from the back of the car, especially one that changes in pitch with different engine speeds, is more likely to be a broken baffle in the muffler.
Black smoke indicates that the air-fuel mixture is too rich to burn completely.
White smoke is steam, and is normally visible on a cold day. However, it can also indicate an internal engine coolant leak, especially if accompanied by a pungent odor. Mike Schmitt is General Mgr.at Midas in Effingham. Mike and his staff are simply the best in the business when it comes to servicing your vehicle. Click here to get answers to your automotive questions.