When using FSRealistic with the PMDG DC-6, with the DC-6 Profile, the engine startup shake only occurs when engines 1 and 2 are started. There is no reaction from engines 3 and 4. Usual start sequence is 3, 4, 2, 1 and there is no visible reaction when I start 3 and 4 first but as soon as 2 fires up, I get engine shake and the same when I start 1.