2020 Ford Mustang: misfire or rough idle

Filed Aug 20, 2026 · Engine, Fuel system · AZ

2020 Ford Mustang with the 2.3L EcoBoost engine. The vehicle has a documented history of coolant loss with no visible external leak, consistent with the known coolant-intrusion defect in Ford's 2.3L EcoBoost engines where coolant leaks internally into the cylinders. The vehicle previously threw a cylinder misfire code (P0301) and now shows a crankshaft/camshaft timing correlation fault (P0017). A scan tool confirmed the exhaust camshaft is approximately 18–19 degrees out of correlation. A new variable valve timing oil control solenoid was installed and did NOT resolve the fault, confirming the problem is mechanical — a worn/stretched timing chain. This wear is consistent with the oil dilution and contamination caused by internal coolant intrusion. The problem has been confirmed by an independent service center via scan data. The vehicle is available for inspection. Warning symptoms included the check engine light, a loud rattle on cold startup, and occasional hard/no-start conditions. This is a safety concern because internal coolant loss can cause overheating, cylinder head cracking, and potential engine failure or fire while driving. Repair cost quoted at approximately $2,000. Mileage approximately 54,400.

Filed Jul 21, 2026 · Engine · NJ

I own a 2020 Ford Mustang EcoBoost with approximately 75,000 miles. My vehicle developed a check engine light with diagnostic codes P0300 (random misfire) and P0301 (cylinder 1 misfire). I also began experiencing white smoke from the exhaust during cold starts. An independent repair shop suspects coolant is entering cylinder 1 due to a possible head gasket failure. They have recommended removing the cylinder head to inspect for cracks, check for warping, pressure test the head, inspect the cylinder walls, and replace the head gasket and related components if no further engine damage is found. The vehicle was properly maintained, and these symptoms appeared unexpectedly.

Filed May 7, 2026 · Electrical, Engine · CA

Check engine light came on, car lost power on highway. Car continues to have the same issue after repairs have been made. Ford App says engine misfire, after every repair. Ford mechanics fix spark plugs, coils, electrical. None of which has fixed the issue of stalling on the highway which poses risk of me the driver and others driving on the highway. The only light that comes on is engine light.

Filed Apr 28, 2026 · Engine, Transmission · IN

IMRC actuator rod broke causing the air/fuel mix to be sporadic. Creating a misfire on random cylinders. Major loss of power and very jerky motions, causing the vehicle to loose control. Luckily it was on an open spacious road. Unfortunately this has been an ongoing problem and there is nobody selling updated parts the electronics will recognize and very difficult to find oe replacement parts, real costly. And may fix the issue for a short period of time. I have a brand new manifold off of a same totaled mustang since Dec 2025 and the same part broke.

Filed Aug 28, 2025 · Electrical, Engine · TX

1. 2020 Mustang Ecoboost is equipped from factory with redesigned block to minimize/eliminate coolant intrusion and or head gasket failure. I still had the dreaded "ecoboom" issue with coolant intrusion on two cylinders as a result of a broken head gasket and poor engine block design. Regular maintenance was perfomed and use primarily Top Tier 93 octane fuel. 5K mile interval 5W-50 oil changes according to manual using Ford spec oil full synthetic. Cold Start Misfires and excessive engine shaking are still occurring despite short block replacement by Ford and they won't diagnose properly. 2. Electrical/Audio. Issue with crackling audio, audio skipping and both iPhones and Androids having disconnection issues. Factory reset the Sync module twice, attempted reset by unplugging car battery and also checked alternator. Replaced car battery with fresh battery and issue persists. 3. Powertrain: The 10R80 Auto Transmission is extremely jarring and does not shift smoothly. Hesitates throughout gears, sluggish gears changes. Gives whiplash effect even after a filter and oil change for the transmission with OEM fluid and filter. Premature Transmission gasket housing failure as well causing ATF to leak onto ground.

Filed Jun 10, 2025 · Engine · TX

2020 and above Mustang Ecoboost 2.3L engines are supposed to have the revised engine block design to mitigate coolant intrusion into cylinders and head gasket leak issues. My 2020 model year Mustang Ecoboost with the updated block, is suffering from coolant intrusion into cylinder #1. Confirmed by independent ASE certified repair shop as well as Ford dealership. No Codes. Symptoms includes cold start misfires and cold start white smoke from exhaust. MPG was inconsistent as well since the air/fuel ratio is disturbed by coolant intrusion. Car is at roughly 37K miles. IF ISSUE IS NOT REMEDIED, YOUR ENGINE MAY BLOW UP DURING OPERATION WITHOUT WARNING.

Filed Sep 9, 2024 · Engine · 59,000 miles · FL

The contact owns a 2020 Ford Mustang. The contact stated that the engine overheated while driving at various speeds with the temperature gauge showing that the engine was hot(H). The contact stated that the vehicle hesitated while depressing the accelerator pedal with an engine misfire alert on the Ford App. The vehicle was taken to a dealer where a pressurized test was performed; the test showed no defect with the engine. The contact then took the vehicle to an independent mechanic where the spark plugs, and cabin air filter were replaced, and the fuel system was cleaned. The check engine warning light illuminated soon after the repair. The vehicle was taken back to the dealer where it remained unrepaired. The manufacturer was notified of the failure and a case was filed. The failure mileage was approximately 59,000.

Filed Mar 15, 2024 · Engine · 63,000 miles · NC

The contact owns a 2020 Ford Mustang. The contact stated that while driving at 15 MPH, the accelerator pedal was depressed; however, the vehicle failed to accelerate as intended. The check engine warning light illuminated, and the vehicle was misfiring. Additionally, the vehicle was shaking, and the contact pulled over to the shoulder of the road. The contact turned the vehicle off and restarted the vehicle. The vehicle was driven to the residence. The contact stated that the failure was persistent. The vehicle was taken to the dealer where it was diagnosed with coolant leak into the cylinders and the engine needed to be replaced. The vehicle was not repaired. The manufacturer was made aware of the failure and advised the contact to report the failure to the federal safety agency Hotline. The failure mileage was approximately 63,000.

Filed Mar 13, 2024 · Engine · 66,500 miles · NC

The contact owns a 2020 Ford Mustang. The contact stated that while driving at 15 MPH, the check engine warning light illuminated, and the vehicle lost motive power. The vehicle was taken to a dealer where it was diagnosed that coolant had leaked into the engine, causing misfiring codes and a lack of motive power which resulted in the engine needing to be replaced. The vehicle was not repaired. The manufacturer was notified of the failure. The failure mileage was 66,500.