Charging Issues with Underdrive pullies

GreenMustangGt said:

I know i've read this before, but i wanted to confirm what i found. Ever since my underdrive pully install, my car's voltmeter would hunt down low at idle.

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Hey Kyle

I see my lights dim a bit during idle with mine. I have never paid much attention to the meter however. I idle at around 850. I did once set the idle at 900 and ran it for a while and I noticed the dimming was gone while using the higher setting.

I just replaced just the alt pully with the smaller stock one, and wanted to say that it helped the charging 100%.......i dont know but i could swear that it idles better now also.

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What you think you have noticed could very well be a reality. You got some parameters in the pcm that + or - injector pulse width based upon battery voltage. Since you moved to a different sized alt pulley, the pcm most likely changed your af ratio to a value you Stang responded better to.

Grady