Every 3 months misfires P0304

Hello,

I have a 2017 Hyundai Sonata. Overall I like it but one big issue is every 3 months it misfires and I get error code P0304. On Feb. 4th it misfired and I got P0304 so I took it to a mechanic. He said it was a bad spark plug, they replaced all the spark plugs, and everything was perfectly fine.

Then 3 months later, on May 10th, the exact same thing happened. The car started to misfire, and I got P0304. I took it back to the same mechanic and he said it was a bad coil, because if he moved the coil the issue followed the coil. After replacing the coil the car was perfectly fine.

Today, August 4th once again my car is misfiring and I have P0304. I find it very odd this happens every 3 months. Is it possible the mechanic is somehow breaking it so I keep coming back? I dont know how it would work for 3 months then break.

I also got a letter in the mail from Hyundai saying my warrenty is being extended for "fuel pump filter assembly". Is it possible the fuel pump assembly could be causing the issue? I tried to have a Hyundai dealer look at it but they are booked until Oct, because a new round of recalls just went out for the theft issue.

Anyone have any idea on this? I just want my car fixed. We are going on vacation in a month and dont want to be stranded because of this issue.

Thanks

 

Update: I took my Sonata to another mechanic and he said the spark plug in cylinder 4 had oil on it, it was only 3 months old. The cylinder 4 plug has oil caked on, possible valve seal failure or piston ring failure. He said I need my engine needs to be replaced. He also told me replacing the spark would temp resolve the issue, but eventually I would have the issue again until the engine was replaced. That's exactly what I have been seeing. I did some research and found Hyundai's like mine have a known issue with consuming too much oil, slow acceleration, and issues with the rod bearing. My car has a update installed to tell me if there's a issue with the rod bearings - so far no issues, however when my car is running I can hear the pistons, they seem to loud. My issue seems related to the known Hyundai engine issues

I just dropped off my 2017 Hyunda Sonata with 62,000 miles at a dealer. The "service advisor" told me like 20 times they wont cover a new engine. I had to ask several times for them to just look at the car. This looks like a fight. Can anyone in this situation give me advice on how to make sure Hyundai covers this issue? I have taken care of the car very well, and i have all receipts showing I got oil changes every 6,000 miles. This is a defect in the car, and nothing to do with maintenence or how I drove it. It looks like I'll have to contact corporation or join one of the many class action lawsuits against Hyundai. Anyone have any advice so the dealer takes this more seriously, instead of blowing me off?

Thanks