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Member Since 27 Aug 2008
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In Topic: Voltage Drop issue HELP!

17 May 2017 - 02:12 PM

That sounds like a pretty significant short circuit somewhere.  The voltage drop would be from excess current flow.  Each time the short happens the voltage drops, and to go from 14 to 8 puts a big load on the alternator as it tries to bring it up to 14.


So I am dealing with a wire shorting or a component shorting based off the reading for sure?


It might be that you just have a dangling wire somewhere that is bouncing around.  The high voltage when you start might be because the battery has capacity that is being used and the alternator can supply a charge on top .  As the short continues the battery dies and the alternator can't keep up with the short.  Does the battery get warm while this is happening?  And do you have to recharge the battery to restart the whole process?


I checked and changed all the wiring. I swapped out my main harness, EFi harness, and engine harness with very clean ones I had laying around, so there are no lose wires hanging around  I cant find any components that are getting hot while the car is on. 

The battery has not drained or needed to be recharged yet.


If it's not a loose wire it could be an electrical component that shorts out more as it warms up.  The coil is a possibility.  I think somebody mentioned that.  Whatever it is should be getting hot as the current flows so touching things while the engine is warming up might find something.


I started to eliminate  electrical components by swapping them with others I have but none of them seem to be the problem.

coil, dizzy, transistor, ecu, afm, dropping resistors, all fusible links, ignition switch, starter motor, fuel pump, all relays.


Another thing to check is if you have replaced fusible links with regular wire, or wired something directly to the battery with no fuse.  If it is a short that's draining the battery that quickly, it really should be blowing a fuse or fusible link.  That's the other benefit of fuses, they tell you where the short is.

Thanks for the response, Im going to continue to watch videos on tracking down short circuits, up my electrical knowledge! See If i can give some better descriptions to solve this.

In Topic: Voltage Drop issue HELP!

17 May 2017 - 10:32 AM

In Topic: Voltage Drop issue HELP!

17 May 2017 - 10:23 AM

Swapping parts is not diagnosis. You are wasting time and money.


Learn how to use a voltmeter to diagnose charging circuits/battery. Shouldn't take more than ten minutes using a volt meter correctly.  Google it.


Verify that the battery and alternator are working by taking them to your local parts store.

Thanks for the shared link, I watched a couple of that guys videos and another video On "voltage drop"


After watching the videos which were informative, including the one on "voltage drop" I still am not finding anyone describing the voltage reading I am getting on my multimeter.


Yea Im not proud of my parts replacement strategy, I know its not the proper way. But I do have spares of every part laying around, so I just gave it a shot.




You should probably study up a little more on electrical basics.  You might be killing your own alternators with improper wiring.  You're still having problems describing what's happening.  "moving on the gauge from 12" doesn't tell much.  Describing the problem is 90% of solving it.



Edit - seriously, all that can be pulled from your posts is that your alternator has quit working twice, you have odd readings on your meter, the engine dies after it wars up, and the injectors make a humming noise.  


Here's a question to ponder - how do you know the alternator has quit charging if the reading on your meter is jumping around?


I really need to work at better describing the problem forsure. Its honestly been a while since I have been on forums,  I am pretty rusty at describing in words what My problem has been. Ive done so many things, I guess I am struggling when I write, where to even start. So thanks for letting me know what errors Im posts descriptions.


To answer the statement you left me to ponder above. The alternator has not quit charging(although two have died). I have a old spare one in the car right now i just threw on. The battery reads 14.4V when running. But the voltage starts jumping all over the place. So the voltage will jump from 14.4 to 8v, It will go back to 14.4 then 10.7. It will just keep doing this and get worse the longer I run the engine, until the engine eventually dies.


When I disconnect the alternator, the battery reading goes to 12.6. The voltage will continue to jump as described above


I will make a video to show what i am trying to describe. 

In Topic: Stronger motor mounts

17 May 2017 - 08:53 AM

My question as well. The idea that the OEM mounts were going bad after 6 months is hard to believe. The ones in the race car are 3 years old and are checked often. The ones in the street Z are even older and they're fine.


How the mounts are at idle or at 3000 rpm aren't a concern, I'd like to know what it's like going up to 7000 rpm, down to 3000 and back to 7000 in a matter of seconds at WOT.


My car hasn't been running for a while now, so I cant say.


But the oem mounts weren't bad. They were worn from when they were new. And I could feel noticeable play in the drivetrain causing a drag/and clunk feeling between up and downshifting. Most Z people probably wouldn't think much of it  since these cars are prone to having really severe "Clunk" issues. But I daily drive mine, and it is really noticeable to me, even if its slight.


You can see on the stock mounts the rubber separates from the side on the metal quite quick, causing more engine movement.

In Topic: Voltage Drop issue HELP!

16 May 2017 - 09:30 PM

okay made a few changes to the post.


It runs for about ten minutes until it dies. when you start it back up after that, it dies quicker each time.


Yes I have tried different multimeter, and they read normal on my other cars


I currently do not have the dash board installed. But when it was a few weeks ago, the reading on the voltage gauge read steady at 12v(that was with the alternator disconnected)


There is definitely something off with the system electrically. Two alternators have died.

And also as the voltage reading begins to jump faster and faster on the multimeter, you can hear the injectors make a louder and louder humming noise that sounds like they are being starved of power.

I would put some better numbers on your description and don't use any "etc".'s  "I disconnected the alternator etc"


How long does the engine run before it dies (number of minutes)?  Have you tried another multimeter (maybe you just have a bad meter)?  Does the meter in the dash jump around like the multimeter does (78 has a dash volt-meter and an internally regulated alternator)?


Might be that you don't really have a voltage problem, just an engine that needs an idle speed adjustment.