If you have a bad injector and it's dumping too much fuel in the cylinder it's called "wash out". What happens is the fuel can't be burned (because of excess) and it "washes out" the oil lubricating the rings and will eventually wear the piston, rings, and possibly the block badly. That raw fuel winds up in the crankcase diluting the oil and making the whole engine have trouble from lack of lubrication.
You can narrow down which injector is bad by starting the engine and loosening the injector line at the injector, it will cause the engine to skip from lack of fuel. If it skips there's nothing wrong with that injector, tighten it and move onto the next one and so on.
I had an injector tip come off on a J.D. 2555 once and this is how my brother and I found it.
This is if you have a bad injector, it's a simple test and will tell you if it's an injector or not. If it's not then it could be valve related.
