Da Hell? Electrical Gremlin(s)

[WastedTalent]

Okay so here's a problem I've seen many people experience before, except completely opposite.

Usually when low voltage, rev engine and it'll jump up, hence why at competitions and such, you rev to about 2k rpm. This... is opposite. Rev engine and voltage drops.

So to give the background info first. Big 3 done in 1/0 wire, with factory wire still intact. XS D3400 under hood (brand new) and D3400 in trunk (5 months old, if even that). Alpine 920HD head unit, SMD VM-1 hooked to the remote of head unit (remote to remote) and to the power of amp. Car is a 2013 Mitsu lancer se. That should be all the info that matters, plus a little extra.

So start the car and voltage goes up to 14. Put car in drive and it'll drop down to 12.2 and sometimes 11.8 when I'm on the gas or fully stopped (red light, stop sign, ect). If I'm coasting? 20-30 mph and just off the gas? Voltage rises up to 14.

Now, doesn't always do it. I've gone days without it and almost forget about it doing it but then it comes back and starts up again.

May ask what the conditions are, such as engine hot? Might be the pcm turning off the alt... or how about the system's pull? I've found nothing that triggers this. Engine can be hot or cold. Car's been off for 8+ hours with outside temp of about 50 degrees and it'll do it. Car's been running for over an hour doing 75mph, turn it off to get gas, turn back on and it'll do it. Also done the same (Be off for 8+ hours or run for over an hour) and not do it. The system isn't up or is up and it'll do it. I see no factor that will make it do it.

Today (Yesterday now), I used my remote start (again, happens with remote start and also happens when I start with key, also doesn't happen with remote start and doesn't happen with key. It's completely random) and got in car. Noticed that my head unit's screen was dark, like it was off (can't remember if music was playing or not). The VM1 was on though. (Not sure what that means as remember, remote to remote. Head unit off? VM1 off). I pressed power button for head unit and it came on. Acted as if a fresh installed head unit. But, didn't lose settings. Pre-set radio stations remained in tact. Time was off by an hour, but it updates itself.

I'd say something with the head unit is happening. But, not the case. I noticed this problem awhile ago and so took it a shop, the shop who does the work for me (Yeah yeah, built and not bought, but try working my hours then let's talk). Gave em the keys and the car had the problem right then so they tested everything they could right then. Voltage at the battery was low. 12.4 I believe, and the car was running. So it's before the head unit.

Last little input, when this problem does happen, I experience no performance issues. I mean, when the pcm does tell the alt to relax due to getting so hot (I have experienced that but this is completely different), the car performs different. Those of you who have pcm controlled crap know what I mean. Whenever this problem happens, the ONLY way I know it's happening is by the VM1. Performance is the same with or without the problem, system sounds the same (as first time I noticed this crap, I had it up pretty loud), etc.

#1 suggestion is check connections obviously. Checked. Everything is good.

#2 suggestion is bad alt/voltage regulator. Car is too new so I'd think. Things do happen, lemons are made, but, trying to gather what all it could be. Let's not say lemon. If alt is bad or regulator is bad, why would this problem occur randomly and rarely? Why does it happen upon starting car, or it just doesn't happen? Why would the car hold voltage steady when problem isn't occuring?

#3 is belt slip. Nope. We're good there.

Also, batts don't run that low, unless bad. How in the world can I be at 12 volts without a system running on 2 D3400's? (continually test them with a DMM and they're fine)

The only fix I have found is turn the car off, wait a minute, start it back up. Voltage will then be steady at 14. I have taken it to the dealer who tested all they could. Everything was "good" at the worst, meaning good was the worst rating anything had. They sure don't like aftermarket things though as they don't like my XS battery lol. But they tested it and "Excellent" rating.

Anyone have any clue?

[rockFord_Expedition]

Voltage regulator on it's way out.

Is it an OEM alt?

Go to AutoZone or Oreilly's and they will check it for free.

I would do it now before it damages other things.

[WastedTalent]

That's the info i forgot to put. It is an OEM alt as haven't found a h/o alt for my car yet (looked literally everywhere, yes, all like 20 diff companies)

How do they check the regulator?

[rockFord_Expedition]

They clamp a device on the terminals and have you start your vehicle and let it run for a minute. The handheld machine analyzes different parts of the starting/charging system and what not. That's about all I know.

I asked if you were running oem alt because those tests don't work well to measure amperage on a HO alt but they will troubleshoot an oem model just fine. Like I said, they do it for free.

When your problem is intermittent, it obviously will only tell you what your problem is if it acts up while hooked up to the diagnostic machine.

[WastedTalent]

Clamp device on terminals of the alt? That... won't work. because if i turn car off, it'll start back up and... normal again. And I personally wouldn't let anyone, cept my worst enemy, attempt to hook it up while car's running. my alt is buried. Not like the GM people where "oh hey, I can fit 300 alts right here on top" lol.

[rockFord_Expedition]

they hook it up to battery terminals while its running.

im so jealous of the room those gm's have

[WastedTalent]

Ahh, then yeah. it'd work. just leave it running as i go inside to get someone lol.

And so am I. Not only because of the space but because everyone makes a h/o alt for em. Lol.

But next time it does that, if I'm near an auto store, I'll def do that. Got a trip planned today and won't be near any stores... hell, not even a gas station really. Won't have cell service. Gonna be in the boonies basically so if it happens? Just my normal fix... turn off, wait, turn back on.