Collisional excitation by free electrons of transitions in various ions of the type 2s²2p^q-2s2p^q+1, determines the strength of many semi-forbidden lines observed in quasars. Collision strengths for the transitions N⁺ and O²⁺ 2s²2p² ³P-2s2p³ ⁵S⁰, and N²⁺ 2s²2p ²P⁰-2s2p² ⁴P are calculated from solutions of coupled integro-differential equations. In all cases allowance is made for configuration interaction between 2s²2p^q and 2p^q+2, and all 2s2p^q+1 channels are included.