2011 4.6 Possible Battery/Alternator Issue?

[JennyGen]

Hi all! I'm new to this forum and typically just get on to read others posts so I hope I'm posting this in the right place. Also, I'm not a mechanic by any means; just a girl who's had a lot of crappy vehicles in the past and a love for learning about cars (thanks dad). Forgive me if I sound totally ignorant.

My baby, Sega, has been doing her job and running perfectly up until today. She's 104k miles in. Today I started noticing that at some points when I'd try to take off from slow speeds or a full stop, my acceleration would stall briefly and my power steering would act funky (slightly pulling, not giving into turns as easily). Only once, for an extremely brief millisecond, I saw the red battery icon show up on the display screen. No other warning lights or messages since.

When I pulled into a drive thru and came to a smooth stop, my RPM dropped rapidly from the usual 650-750 it usually rests at to zero and the car shut off while still in gear. Everything else remained on, electric and all. When I went to start it back up, it hesitated and took a few seconds of pressing the ignition to start back up. Luckily I got it started and was able to reverse it out of the drive thru and to the AutoZone that was conveniently on the other side of the parking lot. The AutoZone employee tested my terminal and said my battery was dying. I have an auto parts store I'm loyal to across the street from my home and my car started back up with no problem so I took her back home and planned on getting a new battery.

I'm just curious because I got into the ENG menu to see what the voltage reading on the battery was and I got 14.2V without the engine on. 15V with it started up. It almost died again when I decided to loop it around my leasing office and I came out of a slow turn. Does this sound like a battery issue or something else? I've heard the batteries and electrical issues on Gennys are weird sometimes and I replaced my alternator two years ago and never had problems.

I also just replaced my purge valve solenoid a couple of weeks ago because it was getting faulty and giving me a check engine light if that could be any bit relevant.

Thanks squad!

 

[JennyGen]

*EDIT: I posted this twice because the original post disappeared from my history and I thought it was gone. Did not mean to spam.*

Hi all! I have a weird problem that I haven't experienced before. My Gen is about to hit 105k miles. I replaced the purge valve solenoid last week and my alternator back in October '19 and kept up with my maintenance. My car has been running fine up until yesterday. She was trekking along smoothly until about mid-afternoon when I started noticing when I'd turn at low speeds my RPM would drop and the power steering felt a bit firmer. I got no warning lights with the exception of one mid-turn when the RPM dropped and the battery icon popped up for half a millisecond. Everytime it did this it would take a second to respond to me throttling the gas. At one point in a drive thru, I came to a smooth stop behind a car and left it in drive. As soon as the car reached idle, the RPM dropped from the usual 700-ish mark down to nothing and the car died. Everything electronic stayed on. I got it to restart but it struggled for a few seconds and I took it to AutoZone so they could test my battery, which they said was dying and that I should buy one online when I got home (already done but I have to wait).

I'm not denying that it could be the battery, but has this happened to anybody else? I only had power steering issues when my alternator went out and my power steering was shot. It has died the one time and tried to twice more at stop lights before I'd hit the gas. Otherwise the performance at speed limits and the highway are completely fine. My voltage reading in the ENG menu show 14.2V with just the battery and 14.8-15.0V with the engine running. It doesn't struggle to start up besides the one time after it died in the drive thru.

Thanks!

 

[Shady_panda]

does sound like an alternator issue.

 

[Gunkk]

I agree with the preliminary alternator diagnosis (or internal voltage regulator, which is the same thing). Power steering will go firm with low voltage/current supply (the electric power steering pump draws a lot of current, particularly when stopped or moving slowly).

Stalling COULD be voltage related, but only if something is dragging down voltage from an otherwise healthy battery. Other possibilities are battery fuse, loose battery terminals or a bad ground, but these issues are less common. A sub 500 RPM low idle or near stall could trigger a momentary battery light and hard steering if caused by fuel/air/spark issues.

A stuck-open Purge valve will indeed cause low idle or rough idle and possible stall issues (excessive air, low manifold vacuum, lean condition). But as long as it was installed correctly (i.e. no air leaks) then you should be fine.

Is the Check Engine light still on?

 

[JennyGen]

I agree with the preliminary alternator diagnosis (or internal voltage regulator, which is the same thing). Power steering will go firm with low voltage/current supply (the electric power steering pump draws a lot of current, particularly when stopped or moving slowly).

Stalling COULD be voltage related, but only if something is dragging down voltage from an otherwise healthy battery. Other possibilities are battery fuse, loose battery terminals or a bad ground, but these issues are less common. A sub 500 RPM low idle or near stall could trigger a momentary battery light and hard steering if caused by fuel/air/spark issues.

A stuck-open Purge valve will indeed cause low idle or rough idle and possible stall issues (excessive air, low manifold vacuum, lean condition). But as long as it was installed correctly (i.e. no air leaks) then you should be fine.

Is the Check Engine light still on?

Nope! The check engine light has been off since the purge valve replacement. I took it to a different AutoZone where I actually trust the employees and they confirmed the alternator is dying. Diode failure. The first AutoZone I went to, I cringed when I watched the employee ask his customer if a Hyundai Elantra was a truck... what...?

I'm not surprised it's the alternator now that I think about it because I'm nearly positive the alternator they used back in 2019 to replace my original one wasn't powerful enough. I just noticed today that my high headlight bulb is out for the first time ever so I'm sure that was the cause.

The first one only failed because I let my group of guy friends jump start their car.. not knowing they had no idea what they were doing (until I came outside screaming when saw my headlight flickering due to them hooking up the cables incorrectly).

One of them had a PhD in electrical engineering. You'd think he'd understand how battery circuiting works! Haha.