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View Full Version : Battery loses volts while driving? wtf


03cobrarocks
11-15-2013, 11:02 AM
So my car has always had issues starting, ever since I bought it. I feel like I have to crank it two or three times way to often... But anyway that isn't too bad anymore.

Now I have this wierd thing about my volt meter (on my radar) showing 13.2 to 13.4 right after I start the car and a couple mins after driving it goes down to 12.4 or so. Sometimes it stays at 12.0 - 12.4 range and I am fine but other times it drops as low as 11.6 or 11.8 and that is when it gets iffy.

I have a pretty new battery (2 years old or so) optima yellow top.

Last time it was at the shop they checked the alternator, said it was fine.

They did say the ground connection sucked, but they fixed that I believe.

What else should I look into? It is freaking annoying!

I also have idle issues sometimes with it getting "stuck" at 1800 rpm or so, if I smash the brake pedal really hard it usually lowers the idle...

doubt these are connected, but might be daily driving the car for awhile so would like to get these issues fixed.

Any help appreciated

fha8388
11-16-2013, 11:40 PM
Get your battery tested..

03cobrarocks
12-03-2013, 05:43 PM
Had autozone test the battery and alternator said they were good :(

TrueStreetTim
12-03-2013, 07:27 PM
Check your grounds but it's a pretty common problem with the Termi's and killing alternators. Get an alternator with a good warranty. :emotions34:

re-rx7
12-21-2013, 03:51 PM
My rx7 did the samething. Never really dropped below 11.6. After rebuild it still did that verified through my HKS TT. Going down the hwy was a steady 12.8 or so.

03cobrarocks
12-25-2013, 02:01 PM
My rx7 did the samething. Never really dropped below 11.6. After rebuild it still did that verified through my HKS TT. Going down the hwy was a steady 12.8 or so.


So did you ever do anything about it or just live with it?

Replacing alternator next week so hopefully that fixes things... Or at least helps

03cobrarocks
01-09-2014, 11:58 AM
Replaced the alternator this weekend. Didnt seem to help much.

Next step is going to hook it up to a battery maintainer for a few days and go from there.

Also ordered a multimeter to see if it will tell me anything.

Everytime I go to autozone/oriellys they say my battery is fine, but I have an optima yellow top and hear there testers only work well with cheaper batteries.

Darkhelmet22
01-14-2014, 11:04 AM
Replaced the alternator this weekend. Didnt seem to help much.

Next step is going to hook it up to a battery maintainer for a few days and go from there.

Also ordered a multimeter to see if it will tell me anything.

Everytime I go to autozone/oriellys they say my battery is fine, but I have an optima yellow top and hear there testers only work well with cheaper batteries.

Factory or aftermarket alternator?

Mistergee
01-26-2014, 01:27 AM
My car does the exact thing, the whole idles high, and when I mash the brake it drops down idle, I too have starting issues, and my gauge cluster and lights flicker like if they are pulsing, I have not done anything about it, just the other day I started to hear whisteling noise come from the alternator, that I changed out 2 years ago, I will be changing it out tomorrow since it's still under warranty, I found out that start up issue is due to the fuel pressure regulator sensor above the fuel rail also someone mention that the flicking of the cluster is due to a piece that's behind the cluster, not sure what it's called though. Anyways after I change out my alternator I will let you know if that helps, also one thing that did help out with idle was I cleaned out my tps sensor and dragon throttle body, and I took of my custom tune and reinstalled it.

03cobrarocks
02-04-2014, 01:51 PM
Factory or aftermarket alternator?


Had a factory one in there. Replaced with an aftermarket unit from pa performance.

03cobrarocks
02-04-2014, 01:52 PM
My car does the exact thing, the whole idles high, and when I mash the brake it drops down idle, I too have starting issues, and my gauge cluster and lights flicker like if they are pulsing, I have not done anything about it, just the other day I started to hear whisteling noise come from the alternator, that I changed out 2 years ago, I will be changing it out tomorrow since it's still under warranty, I found out that start up issue is due to the fuel pressure regulator sensor above the fuel rail also someone mention that the flicking of the cluster is due to a piece that's behind the cluster, not sure what it's called though. Anyways after I change out my alternator I will let you know if that helps, also one thing that did help out with idle was I cleaned out my tps sensor and dragon throttle body, and I took of my custom tune and reinstalled it.



Freaking annoying aint it? Do you by chance have a redfire cobra and live in grapevine? A guy at my apartment told me he had a friend with a redfire that had some idling issues, just figured would check

blownaltered
11-07-2014, 05:23 PM
interesting