Ok so I got a new motor built (d16y8)

I bought a new high output alternator from http://www.4alterstart.com which spits out a max 135 amps
battery was what i had for a while.

I have both an autometer voltmeter, and a voltmeter build into my greddy turbo timer...

when cruising around, my car reads at least 14.0 volts (up to 14.4)
when sitting at a light (aka idle) it dips down to about 12.5 volts and sometimes even lower!! (11.8).

I went to an auto shop to test the battery which they said was fine...
they saw the load from the alternator as 60 amps at idle, and they thought that was great.


they had no idea why my voltage dropped...
anything i could check?

 

bump

 

Check the alternator 'C' wire. The ECU grounds that wire when it wants to disable the alternator. Maybe it's sometimes shorting to ground thru worn insulation somewhere?