Q: Car Loses Power And Puffs Out Large Amounts Of Black And Grey Smoke, First Backfire Was Very Loud, with sulfur/exhaust fumes smell.

Hello There, This is quite likely a sign of a failing or clogged catalytic converter. The catalytic converter converts toxic exhaust gases into less harmful pollutants that are suitable to be expelled into the atmosphere. When this is clogged, this causes these gases to be backed up into the exhaust system not allowing the engine to breathe properly. This can often times also cause unburnt fuel to be ignited inside the catalytic converter causing either backfire as you describe or in most cases emitting it out the exhaust in the form of black smoke and a very strong fuel smell. When this happens, the engine is forced to work much harder to expel these gases. This often results in the engine bogging down, hesitating, shaking and causing very poor fuel economy. This should also cause a check engine light to come on as the O2 sensors should be reading the incorrect amounts of oxygen in the exhaust gases if this is your problem. I would recommend having an expert from YourMechanic come to your location to diagnose and replace your catalytic converter.

Hi there. For the engine to backfire, there was a misfire on the engine and the spark plug was fired on the exhaust stroke causing the fuel to burn in the exhaust pipe make a loud bang noise. The black smoke is from fuel and the grey (blue) smoke is from oil. Check the spark plugs and see if they are needing replaced. Check to see if there is a vacuum leak on the engine and if the fuel system is low on pressure. This will make the engine backfire and cause the engine to have a loss of power. If you need further assistance with your engine backfiring, then seek out a professional, such as one from Your Mechanic, to help you.