New hight output alt

Just got my new high output alternator i have already upgraded cables. I got it installed and when im driving gauge is right at 14 volts. When i come down to idle the gauge is moving all around under 14 it isnt steady and if i have a draw it gose down. My question is do i need a external alternator or is there any other ideas why this is happening. Its a 1990 Laredo. Thanks-

Have you confirmed the voltage at the battery while engine is running. The stock gauges are known to not be accurate. Depending on your replacement alt. If may NOT have an internal regulator.

A battery that is close to dying will cause the same symptoms.
Charge the battery and have it load tested at your favorite auto parts store.

High-output alternators are usually happier at higher RPMs.

What is your idle RPM?

What engine?

BTW, this is a double post.

Recall that you can't get full output from an alternator - whatever that rated output happens to be - until up around 3200-3500rpm spindle speed (typically ~1200-1500rpm at the crankshaft.)

If you've got enough load, you'll get a little "flutter" at idle. See if it goes away when you turn accessories off...

Thanks for the help ill have the battery checked. Idle is normal im still working on a low idle once and a while. I know it was a double post. I also have the only engine you could get in a 1990 Laredo 4.0litre!