can use coupled solver to calculate combustion

cfdfans

I use finite-rate or eddy-dissipation calculate combustion of ch4 , when I choose segregated solver the results are ok. But when I choose coupled solver (implicit or explicit) , ch4 is very difficulty to combustion(I have patch the ignition temperture and species), even if the ch4 combustion ,the results are very bad. I wonder can can use coupled solver to calculate combustion ,or there are particular measures to use use coupled solver to calculate combustion . Thanks in advance!!