So I took off my new spark plugs (bosch platinum) that i put on a week ago and found on cylinder # 4 that it has carbon deposit all over the tip. I also looked down into the cylinder and saw that there are carbon pieces or dirt with either fuel or oil on top of the piston. The other three cylinders are fine, all clean. I know my car is running rich from a OBDII scan but is it possble in just one cylinder? There is no blue or black smoke coming out the exhaust but only black when i hit VTEC. Other than that, my car has idling problems and my engine will die when the throttle body is closed like it should so i had to set it open just a little so the car can stay on idling at 900-1200 (varies). I checked all my sensors and cleaned them, they work fine, i just replaced the spark plugs with denso double platinum. I'm at the point where im about to take it to Honda but ill have someone i know to look at the car. He's a honda head and has built many engines. He told me i might have a head gasket that is just starting to go which is leaking into cyl 4. But it can be the mods i have on my car. I dunno what to do so if anyone knows, PLEASE HELP!!!!!!!
My mods are cam gears(set to 0), aem fuel rail with stock injectors and stock fuel pressure regulator, aem cone filter w/ stock tubing, and a skunk 2 cat back. And im not sure if my ecu was messed with but it it is, i was planning on getting a apexi vafc to tune my fuel settings. i bought the car like 2 wks ago and it ran fine when i test drove it. THANX TO ALL!!!

 

maybe a leaking injector on the cylinder. you can balance test the injector maybe.