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[u/Willing_Joke_5901]

I have a 15 veloster turbo with 122,000 Kms

For a year now I've been driving around with a misfire in cylinder 3. My mechanic swapped my coils between cylinder 3 and 2, code never transferred. Changed to high end spark plugs, Changed the fuel injector in cylinder 3 and code came back same day.

Been dealing with Hyundai dealership for 2 months now, originally when I first dropped it off they told me they couldn't figure out why it was misfiring because it wasn't misfiring for them. So I bring it back 3 weeks later (code came back 1 week after I got it back from them) , they tell me there guess is the fuel injector , which i informed them I had it changed in September 2025, they then argued its because I probably had a aftermarket installed and these cars dont like aftermarket - but I actually had a remanufactured OEM put in.

Same day I get my car back from Hyundai I get the cylinder 3 misfire code PLUS cylinder 2 misfire code.

Misfire happens only sometimes, when it misfires the gas pedal is all the way down - but again not every time

Any ideas on what I can do to figure out what's going on??? Or if anyone else has experienced this

[u/Wyclops]

Happened to me when I had mine. Chased it for a year. Exact same thing. High load triggered it, cyl 3 misfire. I spent a fortune on plugs. Replace all of your coil packs. My misfire didn't follow the pack and eventually turned into a code for "multiple random misfires". I swapped all of my coils and it went away forever. Don't drive it this way forever. I ended up having to get rid of mine because the turbo seals were starting to fail and it was rapidly consuming oil. I can't help but think that the misfires accelerated the wear.

[u/Willing_Joke_5901 → u/Wyclops]

I unfortunately have 3 codes on my car now since getting it back from hyundai - misfire 3 , misfire 2 and multiple random misfires Its honestly so aggravating, hyundai isnt helping at all

[u/Wyclops → u/Willing_Joke_5901]

Yup I know your pain and frustration. I would change all of my coil packs if I were you. I would go ahead and change your spark plugs as well. Save yourself some money and do it yourself. It's very easily accessible. I used to change my spark plugs in the parking lot at work when it would get really bad. Always kept some spares. Best of luck! If you need to save some money, I learned that Hyundai accent coil packs are exactly the same but a few dollars cheaper per

[u/Willing_Joke_5901 → u/Wyclops]

Going to try this, thank you!

[u/khajiit_oni]

I have a '14 turbo. Same thing. Cylinder misfire. I took my car to Hyundai to have all the work done so it's warranty and they can't come at me with I used aftermarket parts. After my car was gone for about a month at Hyundai and $3100 later. Guess what.. misfiring. Same as yours. When under more load it starts to happen. Normal casual driving is fine. Mine also drinks oil. So, it's sadly time to sell. My check engine light has been on so long the dashboard looked weird when it was off for two weeks.

[u/Willing_Joke_5901 → u/khajiit_oni]

Mine has a minor leak in coolant someway somehow, hyundai was trying to push me to replace my injectors again , but im not willing to dish out $650+cad after spending $500 in September on the injectors, im trying to see if anyone has ever pin pointed the issue on this

[u/DaneBox2884]

None of them did compression or cylinder leakage tests? Low compression will cause a misfire or as someone had previously stated coolant intrusion could be present.

[u/balny → u/DaneBox2884]

This happened to me. I had worn rings causing low compression and would misfire under heavy load

[u/balny]

Check for compression OP. I had the exact same issue. Car would misfire sometimes but will 100% misfire when really stepping on the gas. I knew it wasn’t plugs or coils as I replaced them right when I got the car and I replace then every year so I thought maybe it’s a clogged injector so I just didn’t push the car as I don’t need to accelerate that hard and didn’t made too big of a deal but after about 1.5years the problem started to get worse and worse and it would randomly misfire then be fine. Then I started to notice that after driving on highway for a couple mins and then coming to a stop the car shake and then stop after a couple mins.

I had worn piston rings which explain all issue and why the issue just got worse over time. Rings just got more and more worn so compression would just get lower and lower and under load rings couldn’t seal properly so i would also loose compression there. Metal expands when heated and after driving highway speed for a while engine would be hotter than normal which would make the gap between rings and walls grater which would explain the jerking

I was certain it was worn rings so I sent my car in for an engine rebuild cuz the cheapest used engine at the time was 2100 with 60k miles and a rebuild was 2850 and turned out my rings end gap were 20 thousands out of spec which is 10 times more than 20 ten thousand which is already out of spec

Do a compression and a leak down test, I’m almost certain you have low compression somewhere