Hello32

So I purchased a 2017 C300 wit 102k miles from the auction. It was misfiring heavy So I put in a new ignition coil and spark plug but didn't fix it. I saw it was dumping excess fuel in cylinder 1 so i had the local mechanic swap the injector. He put an aftermarket injector in and the vehicle ran smooth for about a day. After that misfiring started occurring heavy again. mechanic is saying cylinder 1 has a compression of 90 PSI. I don't understand how the vehicle ran fine for a day after changing the injector. anyone know what I should do?

ygmn

what are other cyl compression values.

90psi is low.