mixing problems

Hello, good afternoon dear friends. My name is Felipe, and I have a 2000 Subaru Forester Turbo. I've been having problems lately. The check engine light came on, and it's throwing two codes: 23 and 13, which are for the oxygen sensor and the camshaft position sensor, respectively. A few days ago, the car was stalling a lot, so I removed the air filter and left it unobstructed. The car ran very well until yesterday when the same problem returned. It's backfiring, the engine won't idle when starting from cold, and it's emitting almost clear smoke with a strong smell of gasoline from the exhaust. I'd like to know what you all think, as I enjoy investigating these things. I'm a first-year automotive mechanics student, and I'd appreciate any advice that might help. Thank you in advance.

Hi Felipe, what I think is that the camshaft position sensor is either faulty, or it's shifted, or the timing is off. If any of this is happening, it's normal that it starts poorly and doesn't run well when cold. The smoke with the smell of gasoline means it's not burning properly...the ignition signal is out of sync because of the sensor, or the timing is off. The oxygen sensor might be measuring too much oxygen due to the poor combustion. You can check the camshaft sensor by measuring its continuity and comparing it to the nominal values. Also, check the condition of its plug or wiring and mounting bracket. It wouldn't hurt to check the valve timing either. If it's off, the crankshaft and camshaft position sensor signals will be out of sync, causing the fuel injection and ignition to occur incorrectly, as will the valve opening and closing times and piston height. In short, a real mess, just like you described. Good luck with it!