EAP teachers often discuss whether or not grammar has a role in an EAP course. They often talk as if EAP is simply about vocabulary, texts, strategies, referencing etc, forgetting that without grammar, there is nothing to hold the vocabulary items together within the texts.
Grammar is an important part of ESP, especially EAP, as, ultimately, all that exists is words on the page or sounds in the air. These words are constructed from parts and inflect (morphology) and occur in sequences (syntax). Like all registers of English, ESP uses prepositions, articles, adverbs etc. So it is obvious that grammar is an important component of any EAP course.
Many people have also said that ESP is for advanced learners and that learners should have learned most of the grammar before they start their ESP course, or that they cannot learn ESP without a good grammatical foundation.