I finally got my Mac UnderDrive Pulley set (came with the Crank Pulley and Alternator Pulley) on my 96 mustang v6 automatic, but now when I'm idling at night with the headlights on.

I get a drastic reduction in my voltage reading the little gauge actually bounces back and forth.... I have a voltage reader on my Cobra Radar Detector and it reads from 13.5 to as low as 12.3
The voltage will jump back up to 13.8 or higher when I'm driving normally though.

Anyone have any suggestions on how to fix this?

Thanks.

 

when's the last time you changed your battery?

 

About 3 months ago I believe.

 

Keep an eye on that gauge cause you need a minimum of 13.5 volts to keep the battery charged.

 

i would put the stock alt pully back on and see if it still happens, if not i wouldnt put it back on

 

what do you mean idling with the headlights on? what's the problem (i think i might be missing something..) but that's the point of udp: to reduce energy to components on your car and kinda convert it from that to hp. it's like a transfer of power.

 

I was looking around for something to help with this problem and I ran across this http://www.vmptuning.com/store/index...&parent=51 .

Do you think this would fix the low voltage at idle?

Should I try just switching back the stock Alternator pulley maybe?

Arggg I dunno. [:@]

 

You said the kit came with an alt pulley so it should be an over drive pulley that you got.

 

Is it possible to set the Idle Speed higher without using a Tuner?

I was thinking maybe the low idle speed I have (about 600 rpms) could be causing the low voltages, setting it to maybe 800-900 rpms would prolly fix it.

Right or wrong?

 

600 rpms sounds too slow. I think that is your problem, maybe around 750 rpms might be better.