Voltage Drop while idling, need some ideas

extreme_audio · Postby **extreme_audio** » June 4th, 2011, 10:54 am

Hy guys i need some help trying to figure out what next i should check. About a week now i noticed when my car, ck2 4g15dohc btw, is idling the the voltage drops from 13.5 to about 12.4 volts. if I turn on anything, lights, ac, ect. it sometimes drops to 12. While driving the car it goes back up to 14-14.5volts.

So far Ive change the alternator 2 times, with one that i bought and swapped back to the original once it was repaired. (By Brent in Arima, dude does real good work) Both alternators were tested out of the car and are working fine. The battery is also new, changed about a month ago and thats fine also. Also +tive and ground wire and ground points are in good condition. All stinger 0agw plus the original wire is in place, installed about 6-7mts ago.

Can the computer in the car cause this problem? any ideas would be greatly appreciated...

anthonyanthony · Postby **anthonyanthony** » June 4th, 2011, 6:50 pm

could it be idle control on engine?
when lights or ac is turned on , the computer suppose to sense this and increase the idle of the engine to maintain a voltage of over 12V.
so check your idle speed control motor/ valve or respective port.

extreme_audio · Postby **extreme_audio** » June 4th, 2011, 9:12 pm

That seems to be working fine. The idle goes up when I switch on the AC. It normally idles at about 700 then goes to about 900 rpm when the ac is on. At times i had to rev up to 2500 - 3000 RPM before the voltage jumps back to 14.5V

Postby **MISHI** » June 5th, 2011, 12:36 am

was this an engine conversion? And if so, when wiring did thay have to do?

extreme_audio · Postby **extreme_audio** » June 5th, 2011, 5:28 am

its the original engine

raybic · Postby **raybic** » June 5th, 2011, 7:47 am

ground the engine properly. groundin kit might help

extreme_audio · Postby **extreme_audio** » June 5th, 2011, 9:48 am

0agw plus the original wire run throughout d car. batt to chassis to engineblock

Postby **MISHI** » June 5th, 2011, 11:03 am

I once had an issue from a conversion and the alternator would only go to correct voltrage after revving the engine... after 2 failed alternators found that the electrician wired a feed to the alternator to the wrong point on the fusebox... straining the alternator itself.

Now I dunno if you have anything aftermarket wired, in the engine bay, but my suggesstion is to check those wiring connections. Check the wires to the fuse box and possibly test the resistance from wires going to the alternator (2 or 3 smaller wires)

Check the alternator fuse and check the belts on the car. I doubt somehow the ECU will cause the alternator issues...

gallantpan · Postby **gallantpan** » June 6th, 2011, 7:11 am

raybic wrote:ground the engine properly. groundin kit might help

X2

extreme_audio · Postby **extreme_audio** » June 6th, 2011, 10:02 am

MISHI wrote:I once had an issue from a conversion and the alternator would only go to correct voltrage after revving the engine... after 2 failed alternators found that the electrician wired a feed to the alternator to the wrong point on the fusebox... straining the alternator itself.

Now I dunno if you have anything aftermarket wired, in the engine bay, but my suggesstion is to check those wiring connections. Check the wires to the fuse box and possibly test the resistance from wires going to the alternator (2 or 3 smaller wires)

Check the alternator fuse and check the belts on the car. I doubt somehow the ECU will cause the alternator issues...

Thks man, will give this a check..