Lights and Volt guage flickering at idle??

[JCDSparky69]

Hello All , New here, love the site.

I have a problem with my '87 GT, it just started a few days ago when I went to leave work the other night. When I start my car everything is fine , no starter drain or weakness sounds, just starts right up, but as soon as it does my volt guage, tach, and any lites that are on ( dash,headlites,or stereo) all flicker very quickly?
The alternator is brand new about 2 months ago, the battery checks out ok (?), the batt is not new but electrically sound. I did a draw test on the starter and only dawing about 276 Amps on cold start with a 850 CA battery , which I am told is fine seeing the draw is equal to or less than half the battery's CA capability.
I did throw on new 10.2 mm VR racing wires and a MSD cap rotor and coil lately and when I put the 10.2 mm coil wire on the car spits sputters and backfires, put the old crappy accel 8mm wire back on the coil only ( the plugs all 10.2mm) it runs like a rocket??? Don't know if there related but I think so.
Could the TFI unit be going bad causing this, I did contact the plug wire manufacturer and they sent me a new coil wire and it did the exact same thing so it's not the wires near as I can tell.
Well it's buggin the hell out of me and can't pinpoint it. I don't wanna just throw parts into it without some kinda knowledge of the root cause of this issue.
Thanks All.
JCD

 

[MaximumRisk]

when I read the title of the thread first thing that came to mind was the alternator, but you said is new. Now, when you say new you mean new, new or newly rebuilt? Most aftermarket rebuilt alternators are hit or miss and usually takes a few trips to the store before you get a good unit. Anyways you can always remove it and have a local Autozone test it for free.
The other problem could be the wires. Maybe (big maybe) they don't have any, or enough, RF protection which could be driving your electronics a little crazy.

Also Check your grounds.

 

[JCDSparky69]

Yeah I thought it could be them too but they have been on there for a month now and I ruled them out. I am still curious if the TFI unit might be going bad as there is no way I know of to test them?
It is possible the alt could be going but if it is still under the napa warranty I will call it takes 10 min to swap out for a new one and I have to run out for lunch anyways.
Ill call them and see
And as far as the RF protection , that is why I bought those wires they said superior RF protection but could they be wrong?

 

[MaximumRisk]

I still think its the alternator. Start with that. Take it out and have them test it to see if it is bad.
The TFI module is ignition related, it basically tells the coil when to fire. When it goes bad the car missfires, shuts off, or won't start at all.

 

[JCDSparky69]

Yeah I just got off the phone with my local Napa where I got it and they told me it only had a 30 day warranty and I said BS. So because I spend bout 10K a month in there he is going to test it tonite and jimmy the paperwork around if it is bad. Will let you know how I make out when I get home . As luck would have it it is snowing here today and my napa is 2 blocks from the house and I work 1 1/2 miles from napa. Thank you
JCD

 

[JCDSparky69]

Okay just went for a ride to the bank and stopped at my place and left it running. When I first started it up it was doing it , went down the road and noticed it only does it (flickering, needle bobbing) at or near idle RPM's . I let it idle at my house for 5 min and came back out and it wasn't doing it anymore ? But on the down side I only live mile and a half from work which really isn't enough time for my car to get up to temp. I don't have alot of time to let warm up in morning but I could let it run a few min before I leave work though. just throwin it out there
JCD

 

[JCDSparky69]

Hey Maximum where in the Bronx r u . My father was a firefighter there for 35 yrs he retired about 6 yrs ago and has recently passed a few weeks ago. He was in engine 41 on 141st street. We used to ride the fire engines to opening day at Yankee stadium every year.

 

[MaximumRisk]

I still believe its the alternator, but just have it tested to be sure.
I live in the Northern are of the Bronx, near Gun Hill Rd.