I have a Fiat Punto MK2 with a petrol engine. It initially had a faulty ignition coil that would cause the car to idle rough when the engine gets hot.
Few days ago, I changed it along with spark plugs. When I removed the spark plugs, I found that there is dark soot on all 4 of them.
The same day, I started smelling fuel inside the car and there was black fumes from the exhaust. However I'm not very confident that these problems started after the repairs. I suspected a fuel and exhaust smell 2 days before the repairs but wasn't sure it came from my car and didn't mind to check.
I decided to check the new spark plugs suspecting a loose spark plug and discovered that they were all black already and a bit wet. I cleaned them and put them again and made sure they are tight but the problem remained. This led me to believe that I'm running on a rich mixture.
The next day I cleaned the throttle body and tried to figure out the problem and while I was revving while idle and checking for smell and smoke, I got a check engine light that lasted for a few seconds and the code was a faulty lambda sensor. I decided to remove the sensor all together to make the car run on the default value. The black fumes from the exhaust stopped completely but the odors of fuel and smoke are still lingering. Now, when I drive the car (without the lambda sensor), when it is idle, sometimes it starts revving to about 2000 rpm and the fuel and smoke odors are still present although much less.
I don't know where to go from this point on.
