been having issues where im loosing voltage as i turn things on such as..lights,radio turned up loud..even turn on the heat .... when all 3 are on its causing shitty idle and if my system and heats on at the same time power on the radio resets..whats goin on here ? oh and my voltage meter goes from 3/4 to 1/2

 

check all your grounds..... and id invest in a 2+ farad capacitor for your sound system and use the proper gauge wires for the amp power and grounds

 

alright ill check all my ground ....but my systems only 150 watts .. you think id need a cap for that?

 

Double check the Black output wire to the alternator at the alternator (bolted to the alternator and usually has a rubber protective cover on it) and see what voltage you are getting with the engine running. If the alternator belt is the proper tension then it is likely that the alternator is not providing sufficient voltage which should be close to 14 volts to 14.6 An upgraded alternator might be in the cards for your system.

 

Or it could be a short someplace in the electrical system. I had a bad battery cable in my old '90 GTU that caused very similar symptoms as you describe. Replaced a couple alternators because they would die after a couple of weeks. A new battery cable fixed the problem for me.

By the way, next time I'd post this in the technical section since it's a technical question. You might get more replies there.

 

don't waste the money on the capacitor, that is just a bandaid for a deeper problem.

 

yeah i wasnt sure where to post it lol ..thanks though im gonna check tension on the alternator and run a voltage test on it

 

Grab a DMM and check your system voltage with the car running. If it's lower than it should be (~14v, I'd have to look up the exact spec on an s4 alt) then check your battery terminals and alternator connectors for corrosion or resistance. Most likely your alternator is worn out and needs to be rebuilt/replaced.

 

since i started a new job i havent had time to mess with it in the daylight but i should be off tomorrow to get to taken a look at it .. i was on my way home from work today and every time my sub hit the voltage would bounce up and down to the beat lol

 

who woulda thought a minor adjustment of a alternator belt would make 100x's difference..steady 1,000 rpm no power drainage and no radio cutting out ! .. lead pipe for leverage FTW

 

You don't want the belt to be so tight that you damage a pulley or the alternator though. There should still be some slight deflection when you press on the middle of the belt. I think the FSM has the exact figures, but I think it's something like 1/2" with 5 lb. of pressure. Might want to look it up.

Glad it was an easy fix.

 

yeah its not too terribly tight..but definatley tighter than it was