Using a combined configuration interaction and many-body perturbation theory approach, we calculate the level energies of 1s^2^2l^q^ and 1s^2^2l^q-1^3l' (1<=q3 transitions of iron ions are compared with the published experimental measurements, and discrepancies are found to be mostly within {+/-}10m{AA}. Similar accuracy is expected for wavelengths of nickel ions. Such accuracy is a significant improvement over that obtainable with standard configuration interaction methods. A complete table of 2l->3l' transition wavelengths of all L-shell ions of iron and nickel is presented.