The generator matrix

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

generates a code of length 21 over Z4[X]/(X^3+2,2X) who´s minimum homogenous weight is 20.

Homogenous weight enumerator: w(x)=1x^0+18x^20+96x^21+6x^22+5x^24+2x^30

The gray image is a code over GF(2) with n=168, k=7 and d=80.
This code was found by Heurico 1.16 in -1.01e-007 seconds.