2026 Hyundai Palisade: misfire or rough idle

Filed Oct 12, 2026 · Engine, Fuel system · CO

The engine misfires and runs very rough when stopped in drive after highway driving, and the vehicle hesitates and struggles to accelerate from a stop. At about 3,000 miles, Phil Long, Colorado Springs diagnosed a failing cylinder 6 fuel injector and replaced it on 22 April 2025. The problem continues after that repair. The condition repeats in the same way. After 15 minutes to 1 hour of interstate driving, I exit the highway. When I stop at the first traffic light on the off ramp, the engine begins idling very rough, and the tachometer shows about 500 RPM. When I shift to park, the idle smooths out. When I shift back to drive, it becomes very rough again. Pulling away from the light is difficult because the vehicle hesitates and does not accelerate normally. This has happened three times since the repair, most recently on [XXX] at about 5,800 miles. The check engine light did not come on. Conditions: 80 F, clear weather. [XXX] exit [XXX]. This is a safety concern because the vehicle may not accelerate when I pull into an intersection or merge into traffic. Other 2026 Palisade owners have reported similar misfires and hesitation, and Hyundai issued TSB 26-01-068H (Service Campaign 9D6) for engine misfires on 2026 Palisade 3.5L vehicles. I have asked Hyundai to confirm whether this campaign has been performed on my vehicle. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

Filed Oct 11, 2026 · Acceleration, Driver assistance · FL · crash

On September 21, 2026, at approximately 9:20 AM, while attempting to turn off the engine of the parked vehicle, the engine failed to shut down as commanded. Due to severe ECM misfire and erratic anti-stall compensation, the engine surged uncontrollably and propelled the vehicle forward. The Forward Collision-Avoidance Assist (FCA) completely failed to detect the obstacle, alert the driver, or apply emergency braking, resulting in an unavoidable low-speed collision and slight front-end body damage. The following day, on September 22, 2026, at approximately 2:49 PM, the vehicle abruptly triggered a powertrain fail-safe mode in traffic, forcefully restricting speed to roughly 20 mph (limp-in mode), when my wife found it when trying to running faster from a STOP mode, to prevent catastrophic catalytic converter damage caused by persistent combustion misfires. It is impossible to be the wrong operation of my wife since limp-in mode cannot be activated during low speed running. On September 23, 2026, the vehicle was taken to an authorized Hyundai dealership to apply pending TSB 26-01-068H (Campaign 9D6). While the dealer completed the software update and reported no active DTCs remained afterward, Hyundai Motor America has flatly denied manufacturer liability for the property damage incurred directly prior to this safety remedy. Hyundai's ECM software logic flaw poses a critical safety risk involving unintended acceleration, complete shutdown failure, and active safety system non-intervention. I request the federal safety agency investigate this defect and Hyundai's refusal to remediate related incident damage.

Filed Jul 22, 2026 · Engine, Transmission · TX

My car is misfiring. It WILL NOT accelerate as it should. It is like bogging down unable to accelerate when it needs to. It’s struggling. Hyundai is aware of the issue and making owners drive regardless while they “wait for a fix”. It’s extremely dangerous. I’ve almost been hit several times trying to merge onto a highway because it will not accelerate. I’ve had total loss of power one time, putting me and my infant in extreme danger. This has been happening since APRIL.

Filed Apr 16, 2026 · Engine · CA

While driving on a California freeway at approximately 70mph, the engine check light began flashing, the vehicle experienced a sudden and severe power loss, entered reduced power mode, and began violently shaking. Engine braking occurred without brake light activation, creating an immediate rear-end collision risk from following traffic. The vehicle would not stop shaking until restarted. This occurred twice — once in January 2026 and again in March 2026, both on the freeway with passengers in the vehicle. The dealer confirmed fault codes P0303 (Cylinder 3 Misfire), P0306 (Cylinder 6 Misfire), and P0300 (Random/Multiple Misfire) on both visits. On the first visit the dealer called the codes normal and returned the vehicle unrepaired. The second visit lasted 44 days. The dealer could not reproduce the fault during the entire 44-day period. A Hyundai Field Service Engineer physically visited the dealership and applied a special software update to the Engine Control Module. The closed repair order documents this as "UPDATE SPECIAL SOFTWARE INTO ENGINE CONTROL UNIT" with no TSB number, no software version before or after, and no GDS event number. The dealer confirmed they have no access to this update and cannot verify what was changed. No Proof of Correction was issued for California emissions compliance. The two recalls performed on the same repair order both have proper TSB numbers and STUI documentation. The ECM update has none. Concerned about emissions compliance and potential fault code suppression on a California-registered vehicle.

Filed Dec 30, 2025 · Engine · OR

I have been continuously receiving check engine notifications that show the engine cylinders misfiring. This seems to only happen at highway speeds which could cause a safety hazard should the driver need to accelerate for merging/passing/etc. I have brought this issue into the dealership once so far and they said they couldn't do anything since they were unable to replicate the issue while driving it. From what I've seen online, many other owners of this vehicle are having similar problems with the same responses from their local dealerships.