PSA for Hyundai Nu engine owners: Check your ignition system!

Messages
389
Location
Oklahoma
Within the last year I purchased a 2018 Hyundai Elantra with 23K miles. It's not my first Nu engine, but it's the first one I've had an issue with. It currently sits at 28,718 miles. During the extreme cold we saw recently, it developed what I truly thought was some sort of transmission issue. It reminded me of a 4R70W with a torque converter shuddering, just a little less rapid and less consistent. No check engine lights, no other indicators. I monitored it carefully and it persisted, regardless of gear, throttle, or speed. The final straw was when it tried to surge forward while I was in drive at a complete stop with my foot on the brake. It went to the dealer because it's under warranty for 5/60. They had it for almost two weeks (without a loaner :mad:, thank you Thetas...) and couldn't duplicate the issue.

I drove it back home last Monday, nothing. It sat until Friday morning until my buddy picked it up and drove it to his work (a dealership next to my Hyundai dealer) because he was going to detail it after work. After his shift he drove it around back and he noticed the same issue at a stop. He put it in park, and the problem continued. That was what sparked my curiosity.

Additionally, my sister just test drove (and bought last night) a 2017 Tucson with the same 2.0L Nu engine (the only differences being GDI and on this particular one, AWD). She brought it to me to do a pre-sale inspection and complained of the same symptoms. It checked out other than that one issue. But I was overwhelmed with curiosity.

Now that my Elantra is back in my garage and detailed, I decided to do some deep research. After a whopping 20 minutes of research online for "2018 Elantra transmission issues" it quickly morphed into "2018 Elantra misfire/coil/plug issues." Example links here and here. I always check everything before I buy a vehicle, then recheck once it's home. But I'll admit the one thing I didn't check was spark plugs, because I assumed a "100,000 mile" Iridium plug would be perfectly fine at 23K. Well, you know what they say about assuming...

When I pulled the plugs, I confirmed everything I read online. I was shocked. The plugs were atrocious, and the coil boots showed chalky residue at the tips (which the camera couldn't really emphasize, but I believe this to be evidence of a misfire condition). It's sad to see Hyundai not go with NGK like plenty of their other years and models. This is what I found:

20210310_172727.jpg


20210310_172807.jpg


20210310_172857.jpg


20210310_174445.jpg


20210310_174514.jpg


20210310_174542.jpg


Aside from the horrors above, I did find an additional abnormality within the cylinder #4 boot (Hyundai I believe is driver's side 1 to passenger side 4. Someone please correct me if I'm wrong). The other three looked perfectly clean and new inside as you can tell from the image immediately above, but the #4 boot looked like this:

20210310_174838.jpg


I went back to the dealer with the plugs in-hand and explained why they couldn't find a transmission issue. Sorry, I'm going to go off-track and type what happened...I asked what the warranty is and was told it's on me to replace. I was dealing with the assistant service manager, and I've had a phone conversation with him prior. He is a complete tool, but I was still polite since I'm the one asking for something. He pulled my vehicle information and said "That's normal, plugs get dark....what kind of fuel do you use?" I replied "normal 87 octane E-10, just like everybody else." He assumed he had his 'gotcha' moment and replied with "Hyundai recommends 100% gasoline, so that's probably your problem." Little did he realize I'm not stupid and asked him to show me where that recommendation is stated, because it clearly states "do not use gasohol containing more than 15% ethanol" and "Discontinue using gasohol of any kind if drivability problems occur" in the owner's manual. That's exactly what I did (good thing I live in a place where I can get 100% gasoline).

20210310_203341.jpg


A customer walked in and he changed the subject and arrogantly said "look, it's not uncommon for plugs to need changed at even 45K on turbo and GDI vehicles. I've been doing this for 10 years, this is nothing new. So... we charge $189.99 for plugs and labor." I arrogantly replied back "what relevance do GDI or turbos have exactly?" He replied in a tone like I was stupid and said "your Elantra has GDI." I rightfully replied with the same stupid tone "and you've just lost all credibility in this conversation, so please call the REAL service manager so the big boys can talk." He persisted. "I'm not here to argue. All 2011 and newer Hyundais are GDI, but believe what you want." So I snapped back with "No, I bought the car specifically because it does NOT. So let's put the fake news to rest." I pulled out a photo on my phone that I took prior to leaving for the dealer and zoomed in to see this:

20210310_125715.jpg


After pointing to those three letters I said "I'll speak to your boss now." He stormed off. The other advisor present the whole time went to get the manager without a word.

It seemed like the manager (that I liked dealing with on the last visit) wasn't aware of what just happened so I started fresh and polite. I explained again. He said the last time that he's no technician, and had a humble manner. I showed him the plugs and he immediately called his senior tech over. He agreed with me that is was NOT normal especially for the mileage. He also (without prompt) said that coils for the '17+ Elantras are a well-known problem already. The manager then looked in a book a bit extensively and said "you have coverage for 5/60, but we can't just give you plugs. We'd have to pull them ourselves and prove they are faulty to satisfy Hyundai" (which is 100% true) and I agreed. I didn't shoot myself in the foot, but I think he actually is wrong when he said plugs are covered. Regardless, he stated I'd be taken care of, even if it means getting Hyundai Customer Care involved.

Moral of the story, don't assume the plugs and coils are good on 2017 and newer Nu engines. Hyundai needs to recall these, but at the very least, issue a TSB. I'll be sure to reply back with updates as I learn more. Hopefully this helps someone with a misfire/shudder/transmission/shifting complaint like I had.
 
Messages
5,605
Location
NJ
One plug to the far left looks like it has a chipped electrode.

This hybrid approach of troubleshooting yourself but then wanting the dealership to cover repairs never seems to work out well. Either change the plugs yourself or just let the dealership find the problem. You had the loaner so there was no rush. Maybe tell them that your cousin thinks it might be the plugs or coils.
 

OilMagnate

Thread starter
Messages
389
Location
Oklahoma
One plug to the far left looks like it has a chipped electrode.

This hybrid approach of troubleshooting yourself but then wanting the dealership to cover repairs never seems to work out well. Either change the plugs yourself or just let the dealership find the problem. You had the loaner so there was no rush. Maybe tell them that your cousin thinks it might be the plugs or coils.
I thought that too, but it's just a shiny white spot.

And I did NOT have a loaner. "(without a loaner :mad: )" They basically said they don't plan to have loaners for a long time because of all of the Theta engine replacements they have to do. I was hoping to show them the plugs and then they schedule my repair so I don't have to go without a vehicle again. I'm just not looking forward to intentionally exposing it to further misfire issues...

I guess on the bright side... this whole fiasco let me see the piston tops through the plug holes. They look almost brand new. So new that I can still see the circular lines around the center.
 
Messages
3,243
Location
USA
Yes there's been sparking inside the boot on that one, leading to all that yellow stuff inside. Could be a crack in the plug insulator where the line is. Need to replace that plug, coil, boot and all. It's burnt up.

It's been running on 3 cylinders a lot because of that.

The white stuff on the outside of the boot and the yellow brown color of the insulator right above the metal are results of corona discharge, which is normal.

This is a parts failure outside the cylinder which is immediately clear on visual inspection. It has nothing to do with fuel type or anything inside the cylinder.
 
Last edited:
Messages
220
Location
Toronto
Hope this helps... TSB on misfires...





Within the last year I purchased a 2018 Hyundai Elantra with 23K miles. It's not my first Nu engine, but it's the first one I've had an issue with. It currently sits at 28,718 miles. During the extreme cold we saw recently, it developed what I truly thought was some sort of transmission issue. It reminded me of a 4R70W with a torque converter shuddering, just a little less rapid and less consistent. No check engine lights, no other indicators. I monitored it carefully and it persisted, regardless of gear, throttle, or speed. The final straw was when it tried to surge forward while I was in drive at a complete stop with my foot on the brake. It went to the dealer because it's under warranty for 5/60. They had it for almost two weeks (without a loaner :mad:, thank you Thetas...) and couldn't duplicate the issue.

I drove it back home last Monday, nothing. It sat until Friday morning until my buddy picked it up and drove it to his work (a dealership next to my Hyundai dealer) because he was going to detail it after work. After his shift he drove it around back and he noticed the same issue at a stop. He put it in park, and the problem continued. That was what sparked my curiosity.

Additionally, my sister just test drove (and bought last night) a 2017 Tucson with the same 2.0L Nu engine (the only differences being GDI and on this particular one, AWD). She brought it to me to do a pre-sale inspection and complained of the same symptoms. It checked out other than that one issue. But I was overwhelmed with curiosity.

Now that my Elantra is back in my garage and detailed, I decided to do some deep research. After a whopping 20 minutes of research online for "2018 Elantra transmission issues" it quickly morphed into "2018 Elantra misfire/coil/plug issues." Example links here and here. I always check everything before I buy a vehicle, then recheck once it's home. But I'll admit the one thing I didn't check was spark plugs, because I assumed a "100,000 mile" Iridium plug would be perfectly fine at 23K. Well, you know what they say about assuming...

When I pulled the plugs, I confirmed everything I read online. I was shocked. The plugs were atrocious, and the coil boots showed chalky residue at the tips (which the camera couldn't really emphasize, but I believe this to be evidence of a misfire condition). It's sad to see Hyundai not go with NGK like plenty of their other years and models. This is what I found:

View attachment 48692

View attachment 48693

View attachment 48694

View attachment 48724

View attachment 48726

View attachment 48727

Aside from the horrors above, I did find an additional abnormality within the cylinder #4 boot (Hyundai I believe is driver's side 1 to passenger side 4. Someone please correct me if I'm wrong). The other three looked perfectly clean and new inside as you can tell from the image immediately above, but the #4 boot looked like this:

View attachment 48728

I went back to the dealer with the plugs in-hand and explained why they couldn't find a transmission issue. Sorry, I'm going to go off-track and type what happened...I asked what the warranty is and was told it's on me to replace. I was dealing with the assistant service manager, and I've had a phone conversation with him prior. He is a complete tool, but I was still polite since I'm the one asking for something. He pulled my vehicle information and said "That's normal, plugs get dark....what kind of fuel do you use?" I replied "normal 87 octane E-10, just like everybody else." He assumed he had his 'gotcha' moment and replied with "Hyundai recommends 100% gasoline, so that's probably your problem." Little did he realize I'm not stupid and asked him to show me where that recommendation is stated, because it clearly states "do not use gasohol containing more than 15% ethanol" and "Discontinue using gasohol of any kind if drivability problems occur" in the owner's manual. That's exactly what I did (good thing I live in a place where I can get 100% gasoline).

View attachment 48762

A customer walked in and he changed the subject and arrogantly said "look, it's not uncommon for plugs to need changed at even 45K on turbo and GDI vehicles. I've been doing this for 10 years, this is nothing new. So... we charge $189.99 for plugs and labor." I arrogantly replied back "what relevance do GDI or turbos have exactly?" He replied in a tone like I was stupid and said "your Elantra has GDI." I rightfully replied with the same stupid tone "and you've just lost all credibility in this conversation, so please call the REAL service manager so the big boys can talk." He persisted. "I'm not here to argue. All 2011 and newer Hyundais are GDI, but believe what you want." So I snapped back with "No, I bought the car specifically because it does NOT. So let's put the fake news to rest." I pulled out a photo on my phone that I took prior to leaving for the dealer and zoomed in to see this:

View attachment 48764

After pointing to those three letters I said "I'll speak to your boss now." He stormed off. The other advisor present the whole time went to get the manager without a word.

It seemed like the manager (that I liked dealing with on the last visit) wasn't aware of what just happened so I started fresh and polite. I explained again. He said the last time that he's no technician, and had a humble manner. I showed him the plugs and he immediately called his senior tech over. He agreed with me that is was NOT normal especially for the mileage. He also (without prompt) said that coils for the '17+ Elantras are a well-known problem already. The manager then looked in a book a bit extensively and said "you have coverage for 5/60, but we can't just give you plugs. We'd have to pull them ourselves and prove they are faulty to satisfy Hyundai" (which is 100% true) and I agreed. I didn't shoot myself in the foot, but I think he actually is wrong when he said plugs are covered. Regardless, he stated I'd be taken care of, even if it means getting Hyundai Customer Care involved.

Moral of the story, don't assume the plugs and coils are good on 2017 and newer Nu engines. Hyundai needs to recall these, but at the very least, issue a TSB. I'll be sure to reply back with updates as I learn more. Hopefully this helps someone with a misfire/shudder/transmission/shifting complaint like I had.
Within the last year I purchased a 2018 Hyundai Elantra with 23K miles. It's not my first Nu engine, but it's the first one I've had an issue with. It currently sits at 28,718 miles. During the extreme cold we saw recently, it developed what I truly thought was some sort of transmission issue. It reminded me of a 4R70W with a torque converter shuddering, just a little less rapid and less consistent. No check engine lights, no other indicators. I monitored it carefully and it persisted, regardless of gear, throttle, or speed. The final straw was when it tried to surge forward while I was in drive at a complete stop with my foot on the brake. It went to the dealer because it's under warranty for 5/60. They had it for almost two weeks (without a loaner :mad:, thank you Thetas...) and couldn't duplicate the issue.

I drove it back home last Monday, nothing. It sat until Friday morning until my buddy picked it up and drove it to his work (a dealership next to my Hyundai dealer) because he was going to detail it after work. After his shift he drove it around back and he noticed the same issue at a stop. He put it in park, and the problem continued. That was what sparked my curiosity.

Additionally, my sister just test drove (and bought last night) a 2017 Tucson with the same 2.0L Nu engine (the only differences being GDI and on this particular one, AWD). She brought it to me to do a pre-sale inspection and complained of the same symptoms. It checked out other than that one issue. But I was overwhelmed with curiosity.

Now that my Elantra is back in my garage and detailed, I decided to do some deep research. After a whopping 20 minutes of research online for "2018 Elantra transmission issues" it quickly morphed into "2018 Elantra misfire/coil/plug issues." Example links here and here. I always check everything before I buy a vehicle, then recheck once it's home. But I'll admit the one thing I didn't check was spark plugs, because I assumed a "100,000 mile" Iridium plug would be perfectly fine at 23K. Well, you know what they say about assuming...

When I pulled the plugs, I confirmed everything I read online. I was shocked. The plugs were atrocious, and the coil boots showed chalky residue at the tips (which the camera couldn't really emphasize, but I believe this to be evidence of a misfire condition). It's sad to see Hyundai not go with NGK like plenty of their other years and models. This is what I found:

View attachment 48692

View attachment 48693

View attachment 48694

View attachment 48724

View attachment 48726

View attachment 48727

Aside from the horrors above, I did find an additional abnormality within the cylinder #4 boot (Hyundai I believe is driver's side 1 to passenger side 4. Someone please correct me if I'm wrong). The other three looked perfectly clean and new inside as you can tell from the image immediately above, but the #4 boot looked like this:

View attachment 48728

I went back to the dealer with the plugs in-hand and explained why they couldn't find a transmission issue. Sorry, I'm going to go off-track and type what happened...I asked what the warranty is and was told it's on me to replace. I was dealing with the assistant service manager, and I've had a phone conversation with him prior. He is a complete tool, but I was still polite since I'm the one asking for something. He pulled my vehicle information and said "That's normal, plugs get dark....what kind of fuel do you use?" I replied "normal 87 octane E-10, just like everybody else." He assumed he had his 'gotcha' moment and replied with "Hyundai recommends 100% gasoline, so that's probably your problem." Little did he realize I'm not stupid and asked him to show me where that recommendation is stated, because it clearly states "do not use gasohol containing more than 15% ethanol" and "Discontinue using gasohol of any kind if drivability problems occur" in the owner's manual. That's exactly what I did (good thing I live in a place where I can get 100% gasoline).

View attachment 48762

A customer walked in and he changed the subject and arrogantly said "look, it's not uncommon for plugs to need changed at even 45K on turbo and GDI vehicles. I've been doing this for 10 years, this is nothing new. So... we charge $189.99 for plugs and labor." I arrogantly replied back "what relevance do GDI or turbos have exactly?" He replied in a tone like I was stupid and said "your Elantra has GDI." I rightfully replied with the same stupid tone "and you've just lost all credibility in this conversation, so please call the REAL service manager so the big boys can talk." He persisted. "I'm not here to argue. All 2011 and newer Hyundais are GDI, but believe what you want." So I snapped back with "No, I bought the car specifically because it does NOT. So let's put the fake news to rest." I pulled out a photo on my phone that I took prior to leaving for the dealer and zoomed in to see this:

View attachment 48764

After pointing to those three letters I said "I'll speak to your boss now." He stormed off. The other advisor present the whole time went to get the manager without a word.

It seemed like the manager (that I liked dealing with on the last visit) wasn't aware of what just happened so I started fresh and polite. I explained again. He said the last time that he's no technician, and had a humble manner. I showed him the plugs and he immediately called his senior tech over. He agreed with me that is was NOT normal especially for the mileage. He also (without prompt) said that coils for the '17+ Elantras are a well-known problem already. The manager then looked in a book a bit extensively and said "you have coverage for 5/60, but we can't just give you plugs. We'd have to pull them ourselves and prove they are faulty to satisfy Hyundai" (which is 100% true) and I agreed. I didn't shoot myself in the foot, but I think he actually is wrong when he said plugs are covered. Regardless, he stated I'd be taken care of, even if it means getting Hyundai Customer Care involved.

Moral of the story, don't assume the plugs and coils are good on 2017 and newer Nu engines. Hyundai needs to recall these, but at the very least, issue a TSB. I'll be sure to reply back with updates as I learn more. Hopefully this helps someone with a misfire/shudder/transmission/shifting complaint like I had.
 

Attachments

  • MC-10172218-0001_Misfire.pdf
    611.5 KB · Views: 55
Messages
4,481
Location
Central Arkansastan
I thought that too, but it's just a shiny white spot.

And I did NOT have a loaner. "(without a loaner :mad: )" They basically said they don't plan to have loaners for a long time because of all of the Theta engine replacements they have to do. I was hoping to show them the plugs and then they schedule my repair so I don't have to go without a vehicle again. I'm just not looking forward to intentionally exposing it to further misfire issues...

I guess on the bright side... this whole fiasco let me see the piston tops through the plug holes. They look almost brand new. So new that I can still see the circular lines around the center.
The bolded is total BS as well (The part about them not being able to give you one).You've just got a bad dealer. My daughter had engine work done on her 2017 Sonata, and they gave her a new 2021 KONA 1.6T limited to drive while she got hers fixed.
 
Last edited:

blupupher

Site Donor 2021
Messages
6,956
Location
Katy, Republic of Texas
Have not heard of these issues with the Nu.
My mom has one in her '18 Kia Soul (a GDi version).
Just over 30,000 miles right now with no issues so far.
Guess I need to check plugs next time I service it (just did and oil change yesterday).
 
Messages
3,243
Location
USA
The TSB says if the coils are the original type with white dots on top and no ribs on the mounting foot, they'll automatically put in four new ones if you complain of CEL coming on with a misfire code.

The OP's coils appear to have gray dots so that wouldn't apply.

Also since the engine was misfiring but not throwing a code you probably want the software update which addresses that.
 
Last edited:
Messages
415
Location
Southeastern, PA
Call me crazy, but I would just spend the $65 for four new plugs and a new coil and replace them myself. After my five year ownership experience with my 2011 Sonata, I got really tired of dealing with the local service department and know what a headache it can be trying to get them to look into something. Most of the time it was considered "normal" even though it clearly was not.
 
Messages
6,133
Location
Texas Hill Country
So who makes the OEM plugs for the NU engine?

Our 17 Tuscon GDI NU has about 13k miles on it. I'll probably change them out at 30k.

No need for the dealer to do plugs on this type of engine very simple.

Don't buy plugs on ebay or amazon they are probably fake. Get them from a parts store (ask me how I know)
 

OilMagnate

Thread starter
Messages
389
Location
Oklahoma
Good old Hyundai quality. AFAIK, all of their engine families have known defects. Kind of sad really
This is an ignition issue, not an engine defect. The Nus, IMO, are almost perfection and I'd rate them much higher than countless other manufacturer's engines (Honda's Earth Dreams engines come to mind).

I have no defense for the Theta II fiasco or why they continued to use them for so long even knowing the issues...
 
Top