Electrical Car starts, then dies, then kicks back on again.

Vulpes5.0

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Nov 17, 2018
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Warner Robins, Georgia
Hey all, I've got a weird issue going that's got me kind of stumped lately. Haven't been able to find much online.
When I cold start my car (1987 5.0 manual) the RPMs go to 1500-2000, and then the RPMs drop to 0, or close to it, the car acts like it has actually been shut off completely, even going so far as to have the bottom right warning lights turn on, fuel, oil, etc. After it drops to 0, it bumps the RPMS up once again and then idles fine. The key doesn't change position at all, and I've pretty much only had this happen when the car has been sitting for a while. This all happens over the course of about 5 seconds. When this happens it seems to also reset my aftermarket radio settings for some reason. I don't think this would be related to the radio but anything is on the table at this point.

Could be related, a few weeks ago the Tach started going crazy along with a misfire, but it only happened once and I couldn't reproduce it.
 
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General karthief

wonder how much it would cost to ship you a pair
Mod Dude
Aug 25, 2016
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First thing I would do is check the charging voltage at the battery with a volt meter at start up, pay attention to what the volt meter is say'n when it acts up. I'm basing this on the fact that the radio is losing memory when this happens.
 
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Vulpes5.0

Active Member
Nov 17, 2018
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Warner Robins, Georgia
Typical battery voltage = 12.6V
Voltage on startup = about 11 or so
Running voltage = 14.6V

I couldn't get it to reproduce this symptom, but my car has not been sitting for very long so I'll try to give it a day or two and see if it will do it again. Most recently it happened after about 12 hrs of being off. But I can't quite tell if this is a purely random issue or cold start only

Some other notes would be that this is a new Optima red top battery and a new 130 Amp alternator, upgraded a couple months back. The ignition switch is also relatively new, bought from LMR a few years ago.

Happy Easter!
 
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Vulpes5.0

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Nov 17, 2018
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Warner Robins, Georgia
I would say no but stranger things have happend,
I tried again to replicate the issue to no avail, so I guess it's either random or something failing intermittently :(

I have one vague idea though - There is a ground that sits just behind the radio where 2 things ground. One I know is for the radio's ground, and the other I'm unsure of, one wire is red and one is black iirc, but I have moved this ground down to the 2 studs where the factory amplifier mounted because I was getting a lot of audio feedback in my radio.
The original location was on a small rusty dash bracket that sat just behind/above the radio with a 7mm bolt, and I felt it was inadequate for the upgraded power that the new radio would be drawing. It helped the issue to some degree, but I also moved the other ground because I figured they were together, may as well stay that way (especially if it's a better ground, right?)

I wonder if this may be the ground for the ignition switch or something, and when the radio is turned off/on during startup, it could be causing this issue somehow.

PS, here's my radio setup, relocated HVAC, got a 10" sub and amp in the spare tire location, even got a rear view camera going in there. only a little proud of it :D
 

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CAMTWO1070

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Whatever circuit you have your memory wire on could be your issue..Lots just take the wire and wrap it around a fuse and over time that spreads the terminal out causing an intermittent connection..They have piggyback adapters for that task..

Screenshot 2022-04-26 154635.jpg


If the memory wire is wrapped around a fuse its most likely the fuelpump fuse....Fuelpumps pull a bigger load when first started after sitting....

When I do an aftermarket Double Din stereo install I buy the interface wires that hook into the stock stereo plugs and allow it to interface with the deck..

75116-2.jpg
 
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Vulpes5.0

Active Member
Nov 17, 2018
116
16
28
21
Warner Robins, Georgia
Whatever circuit you have your memory wire on could be your issue..Lots just take the wire and wrap it around a fuse and over time that spreads the terminal out causing an intermittent connection..They have piggyback adapters for that task..

Screenshot 2022-04-26 154635.jpg


If the memory wire is wrapped around a fuse its most likely the fuelpump fuse....Fuelpumps pull a bigger load when first started after sitting....

When I do an aftermarket Double Din stereo install I buy the interface wires that hook into the stock stereo plugs and allow it to interface with the deck..

75116-2.jpg
I took my time and made sure that none of my wiring was janky doing this install, I got my conversion harness from Crutchfield and all that. I do think that this issue has something to do with my radio, it seems like this startup problem happens if I let the radio come on before starting the car, like it pulls too much power in some weird way. Where can I find the memory wire? I dont believe i have it wrapped around any fuses. I’ve also yet to try adjusting the ground to see if it fixes this
 

Jose2008

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May 1, 2022
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I had a issue where my mustang died at idle
I fixed it it was a Ground cable.
The car worked fine
 

Vulpes5.0

Active Member
Nov 17, 2018
116
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21
Warner Robins, Georgia
I had a issue where my mustang died at idle
I fixed it it was a Ground cable.
The car worked fine
I went through and cleaned all the under hood grounds while back to make sure that wasn't a problem, all bare metal. it seemed to improve overall running but I may have just imagined it lol
 

Vulpes5.0

Active Member
Nov 17, 2018
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Warner Robins, Georgia
Finally found the root of the problem, as it seemed to only happen after I had messed with the radio settings- My BOSS radio has a function that allows it to stay on for 0-3 seconds after you turn the key to the off position (to i guess emulate newer cars or allow you to go to accessory without the radio resetting)
Somehow or another this keep-on function would cause the funky startup problem, as I haven't adjusted the setting since and it's working fine. maybe it simply draws too much current with the amp, sub, etc and causes an ECU/ radio reset or something odd.
 
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