LT1 Based Engine Tech 1993-1997 LT1/LT4 Engine Related

what can I do to bring the volts up 12.3 I need 13.5

Old Jul 24, 2008 | 11:54 AM
  #1  
Billet ss's Avatar
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what can I do to bring the volts up 12.3 I need 13.5

Went to the dyno and was told and showed I'm lean because my volts are low they were 12.0-12.5 during the run,which had a a/f of 14.2,then made anther run with a charger hooked up to the car it had 13.6 volts and the a/f went to 13.0
What can I do to solve this?
Old Jul 24, 2008 | 11:57 AM
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Is your alternator good? Mine did the same thing when it started to die would only run with 12 to 12.5 volts eventually it killed my battery and the car wouldn't start new alternator fixed it.
Old Jul 24, 2008 | 12:00 PM
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I believe its good,the car has always stayed the the low 12's,I think I'll check it today.I never have staring problems,hell I just started it after 3 weeks?
Old Jul 24, 2008 | 12:11 PM
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Are you going by your gauge? or a meter at the battery?

Also make sure you have good grounds all around - they are as important as anything else in an electrical system.
Old Jul 24, 2008 | 12:49 PM
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scaner on the car grounds are good even added 1.
Old Jul 24, 2008 | 01:04 PM
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Battery is in the trunk right? What gauge wire are you running for your grounds and up to the front?
Old Jul 24, 2008 | 04:06 PM
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alternator should be between 13.5 to 15.5. any less and you need a new alt...or new cables. any more and you'll likely toast the pcm/ecm
Old Jul 24, 2008 | 04:30 PM
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Checking volts with a code scanner can be decieving. I have a 95 Z28 and the scanner reads 12.8-13.2 and a meter reads 14.2 on the batt while running. Chech the volts at the batt while running.

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Old Jul 24, 2008 | 04:48 PM
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12 volts won't toast anything on the car, but it generally is a sign that the alternator is going bad.

That is, of course, assuming that the alternator is actually pumping out 12 volts and that you're not losing a volt or two due to some unknown parasitic draw.
Old Jul 24, 2008 | 09:33 PM
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The difference in the voltage you see across the battery and what the scanner sees is normally real. The PCM is not getting all the voltage. It is often worse in the summer (when ambient temps are high).

I believe it is a voltage drop across the ignition switch and/or it's connection. One of these days I intend to investigate this further and come up with a clean way to circumvent this issue (probably install a relay).
Old Jul 24, 2008 | 09:39 PM
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As noted, in another post he mentions the battery is in the back, and that he used a 1 gage wire. Sound like its too small, possibly not good grounds or sloppy wiring. Do you have a battery kill switch (required)? Is it a high amp rated switch?

Low voltage at the PCM could affect injector pulse widths, but the offset table should compensate for that, unless the injectors are too small. What you need to measure is the voltage at the fuel pump harness connector at the rear axle. Low voltage to the fuel pump will reduce the flow capacity.

You lose continuity on the responses when you start a new thread, and don't at least include a link to the old thread.

https://www.camaroz28.com/forums/sho...d.php?t=622646

Last edited by Injuneer; Jul 24, 2008 at 09:41 PM.
Old Jul 26, 2008 | 10:10 PM
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I tryed putting a new alt,and it brought the volts up to 14.0 at the battery,alt and ax post but with the scanner plugged in the still reads 12.5 and through the cigar lighter with a gauge it reads 12.5,so that would mean the pcm is only getting 12.5? I checked all the grounds that I know = by the ax post,driver front ground strap,small wire by the #6 plug is there any more?
Old Jul 27, 2008 | 10:39 AM
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The stock positive battery cable has 3 wires on it.... large gage black to the starter, and two smaller red wires that go to the alternator and to the "+" distribution box. How did you rearrange those wires when you moved the battery to the back?

How did you wire the grounds? Where does the battery ground in the back?

Did you check the volts at the fuel pump connector over the axle?
Old Jul 27, 2008 | 11:00 AM
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I have a distribution box that I used,the wire coming from the back comes in,a small wire to the post from the box,4 gauge out to the alt and the black wire goes out to the starter? the original battery ground I put on the post in the front,is that wrong? the battery in the back is grounded to the body,could it be that? I didnt check fuel pump volts,but I put a new alt now the volts are 14.3 at the alt,the post and battery,but was still 12.5 on the scanner.I cleaned and checked all the grounds and the scanner volts went up to 12.7-8
Old Jul 27, 2008 | 11:02 AM
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I was thinking of just putting a racetronix harnss on,I see guys getting a volt out of that what do you think injuneer?

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