swapped engine no start

[bmwm42]

so i just replaced the engine in my e30, no start and it spins slowly or not at all. the battery is good and ive doubled checked the connections that i removed when i replaced the engine harness. there are only four. the three on the terminal post the ground for the coil pack the ground from engine to chassis on the passenger side. im stumped ive checked the voltage at the terminals and starter they register 13.4. seems like the issue is a ground somewhere, any ideas are much appreciated

[romkasponka]

check your engine-body earth cable and starter motor power cables for good connection and clean surface where cable terminal goes.

[bmwm42]

check them both check out, where does the fusebox ground at? i know it has to cables from it but are they both power cables?