2018 Hyundai Tucson: misfire or rough idle

Filed Sep 2, 2026 · Engine · TX

I own a Hyundai Tucson 2018 SEL Plus. My problem is my vehicle is coming to the end of it's 100,000 mile warranty. This vehicle started burning oil about 30,000 miles and it got worse. I checked on recalls and there was no recalls for my VIN number for this vehicle. My Hyundai vehicle is burning a quart of oil every 300 miles and this is no exaggeration. I bought the car brand new and had to replace my 1st Catalytic converter at 79,627 miles on 5/14/25 that was originally on the car. The second Catalytic converter that I had put on I, had to replace that Catalytic converter again at my cost at approximately $900.00 and then after that it plugged up again at 91,928 miles on 7/28/26 and I, had to replace that one that is the third one now. The Catalytic converter company had warranted the work and the converter to be installed. This has caused the car to not only misfire, but become a possible road hazard to miss enough and possibly cause it to stall or reduce the power output of the vehicle while in operation and on public roads in traffic and possibly create a major accident on the freeway. This is a major saftey concern being that you could not only lose power while in motion but could lock up the engine. We talked to mechanics, other people that own them and even the service guys at Hyundai knew it is problem. The service genteman said that they would clean the valves I, believe they talked about cleaning the valves with walnuts like sand blasting and I, told him cleaning the valves is not going to do anything for the oil consumption, because the oil consumption is the engine.The engine when it was originally made on the number 3 cyclinder was bored wrong. That is our problem because the oil rings and rings are letting the oil bypass the piston and filing out the iriadium spark plug and our car mileage has gone down because of this the rings are wearing faster and causing us to keep buying newer spark plugs. " Check Engine Light Flashes " plugged Cat Converter.

Filed Jun 10, 2025 · Brakes, Engine · 177,000 miles · PA

The contact owns a 2018 Hyundai Tucson. The contact stated while driving 70 MPH and depressing accelerator pedal, the vehicle started to decelerate. The contact pulled over to the right side of the road and turned off the vehicle. The contact waited for two minutes and attempted to restart the vehicle; however, the vehicle failed to respond as needed. The brake warning light was illuminated. The vehicle was towed to an independent mechanic where it was diagnosed with a misfire in cylinders #1 and #2. The contact was informed that the engine needed to be replaced. The vehicle was not repaired. The contact related the failure to the federal safety agency Campaign Number: 20V543000 (SERVICE BRAKES, HYDRAULIC); however, the VIN was not included. The manufacturer was notified not notified of the failure. The failure mileage was 177,000.

Filed Aug 14, 2023 · Engine, Transmission · MO

This very low mileage vehicle recently had the same incident for I believe the fifth time since I've owned the car. In a very dangerous situation the car exibited the car going almost dead after normal acceleration. It regains power after 3-5 seconds and rapidly returning to acceleration. It happened to my wife soon after purchase and she has refused to drive it since. Last week while I attempted to make a left turn at a yellow light it again went dead and traffic was forced to slow while the car behind me almost rea ended me. Recently the engine seems to run rough at times. Never have I seen any engine trouble lights since I've owned it. Three separate Hyundai dealers have looked at and seemed to be aware of what's causing it, but chose their words carefully. My neighbor owns one of the largest new cars dealerships in the Midwest. I spoke with him about this problem and he said his used car manager would NEVER purchase one with this engine/transmission for resale! A Hyundai service manager told me to get rid of it soon. When told I was planning on gifting it to my daughter, he said he wouldn't... The car only has 33,000 miles and looks new. Always garaged, never driven in snow.

Filed Feb 23, 2023 · Engine · 80,000 miles · OH

The contact owns a 2018 Hyundai Tucson. The contact stated that on various occasions while driving at an undisclosed speed, the check engine warning light illuminated. The contact stated that after taking the vehicle to an independent mechanic for a routine oil change, she was made aware of an oil leak; however, the vehicle was not diagnosed or repaired. The contact stated that the vehicle was stalling while depressing the accelerator pedal while driving at various speeds, and while driving uphill. The vehicle was taken to another independent mechanic, where it was diagnosed that there was a misfire in cylinder #1 and that the engine needed to be replaced. The contact was advised to take the vehicle to a local dealer for repair. The contact stated that after she made a local dealer aware of the failure, she was informed that the engine was discontinued and advised to contact the manufacturer for further assistance. The vehicle was not repaired. The manufacturer was made aware of the failure, and the contact was made aware that the warranty had expired and that she was responsible for the costs of the repair. The approximate failure mileage was 80,000.

Filed Nov 3, 2018 · Engine · FL

At times, while driving with the transmission in drive, the vehicle hesitates to accelerate after being stopped, as at a red traffic signal. When this happens, pressing the accelerator pedal to the floor will start the vehicle moving forward 'very' slowly for about 3 seconds, then it will take off with full power until accelerator pedal is let off. When this hesitation occurs, the engine does not sound or feel like it is straining, or misfiring at all, it seems more like the computer is not sending the engine the signal to rev up and go, hence having to floor it to get it to move. This condition is extremely dangerous, to the point I avoid having to make left turns at traffic light intersections, because I never know when the vehicle is going to exhibit this behavior, but this can happen whether going straight, or making a right-hand turn. This vehicle only has 1,253 miles at present, but this condition has been happening since it was driven off the lot new.