Cylinder 5 Misfire Detected

The head gasket failed at 89,000 miles. The engine gave P0305 Cylinder 5 misfire codes and would run rough causing difficult to drive in standard traffic flow. There are borescope pictures of coolant in cylinder 5. We stopped using the vehicle until the repair can be completed. This appear to be a WIDESPREAD problem for 2017-2019 Chrysler Pacifica which are numerous on the road and could be hazardous if these vehicles failed on regular roads and highways. See [XXX] INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

Truck decelerates while on incline. Engine light did come on. Took Car to Bill Brown Ford dealership. has been at dealer since 2/12/25. Code P0305 due to low compression on cylinder #5 110 PSI, #4 121psi all others at 145-150 psi. was informed necessary to replace long block. The truck was purchased with extended service warranty thru Ford ESP. warranty lists engine replacement is covered. however, ESP not covering it. Research on internet states frequent issues with 2.7 liter ecoboost 2019 Ford F150 has common issues with the cylinders requiring engine replacement

The engine's cylinder head/valve train has failed internally, allowing combustion gases to enter the cooling system — confirmed via a chemical block test performed by a master automotive technician on November 29, 2024, which verified combustion gases present in the coolant. This is a widely documented defect on this engine and model year, related to valve seat erosion in the cylinder head. Symptoms first appeared in June 2018 as an unusual higher-pitched, stressed sound from the engine. Over time this progressed to recurring, confirmed misfires on cylinders 1, 2, 3, and 5 (diagnostic codes P0300, P0301, P0302, P0303, P0305) and a mixture control fault (P219B). The check engine light has…

Hydraulic lifters seize up causing the vehicle to lose power. The check engine light comes on with code P0305 meaning the number five cylinder is misfiring this is due to not having enough oil going to the hydraulic lifter. I have mentioned this to the dealership and they said there is no recall on it but they have had a lot of issues and have parts readily available to fix this problem. The safety problem I am having is I do not have enough power to accelerate into traffic or highway entrances

The engine in my truck failed while driving down the interstate highway (I-10) on May 28, 2026. At the time of failure, a loud popping noise emitted from the engine. Power and speed were reduced as the result of the failure. The Check Engine Light and Service Engine lights illuminated as quickly as the failure occurred. As many vehicles were simultaneously traveling along the highway at speed, my vehicle suddenly slowing down without indication (brake lights) could have inadvertently caused an accident. As a result, I continued driving the vehicle under reduced power to my home which was only approximately 2 miles away. During the 2-mile drive to my home, the loud popping noise intermitted…

WHILE DRIVING THE CHECK ENGINE LIGHT CAME ON WHEN I CAME TO A RED LIGHT I NOTICED THE ENGINE IDLE WAS ROUGH. I CHECKED THE CODE WHEN I GOT HOME P0305 MISFIRE IN CYLINDER NO. 5 I HAD THE SPARK PLUG AND COIL PACK REPLACED CLEARED THE CODE ENGINE STILL IDLED ROUGH AND CHECK ENGINE LIGHT CAME BACK ON. I HAD A MECHANIC LOOK AT IT AND FOUND DEFECTIVE VALVE GUIDE IN CYLINDER NO.5 HE STATED THIS IS A COMMON PROBLEM WITH THIS ENGINE.LESSON LEARNED DON'T BUY DODGE.

Began with a misfire on cylinder 5 code P0305. Replaced spark plugs, wires, and coil pack. Misfire still existed. Fuel injector on cylinder 5 was stuck open and had to be replaced. Misfire still existed. No spark from new coil pack on cylinder 5, replaced coil pack connector. Misfire still existed, but lifter tick became present. Removed cylinder head and found exhaust lifter on cylinder 5 was bad and needed replaced. Currently awaiting parts delivery (only available through GM dealer). Have been without vehicle for 7 weeks now. Was told this was most likely related to Active Fuel Management.

My 2021 GMC Yukon XL Denali with the 6.2L L87 V8 has experienced two significant lifter/valvetrain failures. The first occurred at approximately 6,500 miles and was repaired by a GMC dealer. That failure involved cylinder #4, including a collapsed/stuck lifter and bent pushrod. The current failure occurred at approximately 110,269 miles. The vehicle initially operated normally. While traveling about 10 mph and approaching a major thoroughfare, the engine suddenly began making a loud knocking noise and the vehicle began shaking violently. There were no warning lights or other symptoms beforehand. Three children were in the vehicle. When the driver attempted to accelerate, the vehicle failed…

What happened? Starting in October 2020, my 2019 Jaguar F-Type experienced persistent electrical and fuel injector system failures affecting cylinders 1 and 5, resulting in multiple engine misfires and reduced engine performance. The vehicle’s fuel injector connectors, specifically connector C1E121A, had misaligned pins causing injector circuit faults (DTC codes P0262, P0274) and frequent misfire codes (P0301, P0305, P0300). These defects caused the vehicle to run roughly and unpredictably, creating a safety risk by compromising engine power and potentially causing loss of control, especially during startup and acceleration. Warning lights and engine fault codes were present throughout the…

Check Engine light with Codes: PO300, and PO305. Misfire in Cylinder #5. Changed all spark plugs, and coils. Check engine still on, with same codes. Jeep dealer then said it was the cam shaft and needed new cam shaft head of a price tag of $8500. The car has been well maintained and has 75,200 miles on it. There is a known premature failure with the Pentastar Engine that is in this vehicle. Jeep is refusing to stand behind their product.