620i starting issues

[bigb]

Have a 620i that will start perfectly on initial startup, once it warms up (2-4 minutes) it will not start in crank position on key switch, if engine is spinning fast enough it will start when key returns to run position. Installed new ECU,starter,starter relay, ignition switch voltage regulator. What am I over looking?
It's driving me nuts!

[campoman]

check all your grounds

[bigb]

OK just so if it happens to anyone else, we checked the 2 relays by the battery and that seems to have been the issue. It's been running and starting for 30 minutes as it should.