problem with premixed combustion
 

Hello,

I try to simulate a premixed combustion in a chamber. I inject CH4 and after a certain time I want it to ignite.
My problem is now that CO2 appears in my chamber out of nowhere.(it starts at the boundary and I tried EBU and CFM)
It seems like the combustion is happening before I even ignited it?

Can someone help me and say how I can get rid of this problem?
Any suggestion is appreciated:).