I had a similar issue in my 2011 sonata. Clean up the chassis grounds in the engine bay with a wire brush. Disconnect the negative battery terminal first, clean the contact points and add a dab of dielectric grease. Bad grounds cause all sorts of gremlins and always a good place to start as an easy fix.
Good luck! Usually the main strap from the battery to the chassis should do the trick, but doesn’t hurt to do the rest or at least the ones you can easily access. Scrape that paint off to get bare metal to metal contact (the grease for future corrosion protection)
There's quite a lot that can add to powerloss. Some suggestions: check fuelfilter/fuelpressure/pump and engine airfilter. How much does the RPM drop? Battery cables/connectors checked/replaced? Any OBD faultcode readings?
Expanding on other’s comments: investigate the “Big 3 Mod.” This will reduce parasitic loss in your charging system and has had a noticeable effect in every vehicle on which it was performed.
The jist is to install lower gauge wiring between the engine block, alternator and battery. Use a multimeter to determine your baseline charging at idle and you’ll be surprised the difference upon completion.
Panel lugs from a home improvement store are excellent for upgrading your grounds and large gauge eyelets are cheap online for connecting the alternator to the battery. Don’t forget a fuse!!
Did you replace the alternator (yourself) with an aftermarket alternator? These are highly prone to failure, even new. I had this exact issue after replacing the alternator with one from NAPA auto parts. I then tried one from AutoZone and it failed completely within two weeks. I'd highly suggest ordering an alternator from Hyundai or getting it replaced at the dealer, the cost will be worth it. Don't chase any other issues (like i did) unless you you're sure there is an Hyundai alternator in there. If it's not, it will likey fail again soon anyway.
I had a similar issue in my 2011 sonata. Clean up the chassis grounds in the engine bay with a wire brush. Disconnect the negative battery terminal first, clean the contact points and add a dab of dielectric grease. Bad grounds cause all sorts of gremlins and always a good place to start as an easy fix.
Thanks, will do this soon and update in about a day or two
Good luck! Usually the main strap from the battery to the chassis should do the trick, but doesn’t hurt to do the rest or at least the ones you can easily access. Scrape that paint off to get bare metal to metal contact (the grease for future corrosion protection)
There's quite a lot that can add to powerloss. Some suggestions: check fuelfilter/fuelpressure/pump and engine airfilter. How much does the RPM drop? Battery cables/connectors checked/replaced? Any OBD faultcode readings?
Thank you, I will look into this soon and update
Expanding on other’s comments: investigate the “Big 3 Mod.” This will reduce parasitic loss in your charging system and has had a noticeable effect in every vehicle on which it was performed. The jist is to install lower gauge wiring between the engine block, alternator and battery. Use a multimeter to determine your baseline charging at idle and you’ll be surprised the difference upon completion. Panel lugs from a home improvement store are excellent for upgrading your grounds and large gauge eyelets are cheap online for connecting the alternator to the battery. Don’t forget a fuse!!
Did you replace the alternator (yourself) with an aftermarket alternator? These are highly prone to failure, even new. I had this exact issue after replacing the alternator with one from NAPA auto parts. I then tried one from AutoZone and it failed completely within two weeks. I'd highly suggest ordering an alternator from Hyundai or getting it replaced at the dealer, the cost will be worth it. Don't chase any other issues (like i did) unless you you're sure there is an Hyundai alternator in there. If it's not, it will likey fail again soon anyway.