The generator matrix

 1  1  1  1  1  1  1  1  1  1  1  1  1  1  1  1  1  1  1  1  1  1  1  1  X  X  1  1  X  X  1  1  X  X  1  1  1  1  X  X  1  1  X  1  X  X  X  1 2X+2  0  X  X  1  1 2X+2  0  1  1 2X+2 2X 2X+2 2X+2 2X+2 2X 2X+2  X  X  X  X  1  1  X  X  X  X  1  1  X  X 2X+2  1  1  1  1
 0  2  0  2 2X 2X+2 2X 2X+2  0  2  0  2 2X 2X+2 2X 2X+2  0  2  0  2 2X 2X+2 2X 2X+2  2  2  0  2 2X+2 2X+2  0  2  0 2X 2X 2X+2 2X 2X+2  2  2  0  2 2X+2 2X  0 2X 2X+2 2X+2  2 2X+2  0 2X  0 2X  2 2X+2  2 2X+2 2X+2 2X+2  0 2X 2X+2 2X+2 2X  0 2X  0 2X  0 2X  2 2X+2  2 2X+2  0 2X  0 2X  0  2 2X+2  2 2X+2
 0  0 2X 2X 2X 2X  0  0  0  0 2X 2X 2X 2X  0  0  0  0 2X 2X 2X 2X  0  0  0 2X  0  0 2X  0 2X 2X 2X 2X 2X 2X  0  0  0 2X  0  0 2X  0 2X 2X  0  0 2X  0  0  0 2X 2X  0 2X 2X 2X 2X  0 2X 2X  0 2X  0  0  0 2X 2X  0  0  0  0 2X 2X 2X 2X  0  0  0  0  0 2X 2X

generates a code of length 84 over Z4[X]/(X^2+2X+2) who´s minimum homogenous weight is 84.

Homogenous weight enumerator: w(x)=1x^0+112x^84+12x^88+3x^96

The gray image is a code over GF(2) with n=672, k=7 and d=336.
This code was found by Heurico 1.16 in 0.64 seconds.