The present invention provides a process for manufacturing polyethylene-diene-copolymer conducted in a plant including at least one compressor unit, at least one preheater unit downstream of the compressor unit and at least one reactor, in particular a reactor, downstream of the compressor unit and the preheater unit. The process comprising the steps of (a) feeding a first feed stream comprising ethylene into the at least one compressor unit and subsequently into the at least one preheater unit, and (b1) feeding a second feed stream including at least one diene comonomer to the first feed stream leaving the at least preheater unit, and feeding the combined feed streams including ethylene and the at least one diene comonomer to the at least one reactor, and/or (b2) feeding a second feed stream including at least one diene comonomer to the at least one reactor at at least one location along the reactor.