Misfire Nissan Altima

Understanding the Intermittent Misfire in a 2010 Nissan Altima


The 2010 Nissan Altima has been facing intermittent misfire issues, causing the car to shake, with the “Service Engine Soon” light blinking on and off. OBDII readings indicated a P0301 code, signifying a cylinder 1 misfire. Despite efforts to diagnose and resolve the issue, including a visit to the dealership, the root cause remains elusive. This article aims to delve into the details provided by two separate sources, offering insights into the challenges faced by the owner and potential solutions.

Unraveling the Mystery: Symptoms and Diagnosis

The First Encounter

The misfire episodes are accompanied by knocking sounds under the hood, suggesting a possible loose component. The misfire was temporarily resolved, but the “Service Engine Soon” light persisted, indicating a lingering issue. Additionally, the OBDII reader gave a P0420 code, pointing to an insufficient catalyst. Despite replacing ignition coils and the catalytic converter in the past, the problem resurfaced, leaving the owner perplexed.

Seeking Solutions for Cylinder 3 Misfire

The second article brings forth the specific concern of cylinder 3 misfire. The owner has already changed the coil pack, installed new spark plugs and wires, and confirmed proper functioning of fuel injectors. Yet, the smell of fuel inside the vehicle persists, adding another layer of complexity to the diagnosis.

Potential Culprits and Solutions

Addressing Cylinder 3 Misfire

Vacuum and Valve Issues

The second article suggests investigating misfires at idle to identify potential vacuum leaks or valve sealing issues. Utilizing a compression gauge for dry and wet tests becomes crucial for a comprehensive diagnosis. Valve sealing problems can be challenging, requiring specialized tools such as a vacuum gauge connected to the intake manifold.

Fuel and O2 Sensor Examination

The scan tool is recommended to check pre and post cat O2 sensor values, ruling out injector or fuel-related issues. Fuel pressure gauge usage, coupled with a scanner to activate injectors individually, helps ensure proper fuel injection. Careful interpretation of O2 sensor values is emphasized, considering the possibility of a flooded mixture leading to a lean code.

Tackling Misfires in General

Spark and Fuel Issues

The third article broadens the discussion, highlighting that misfires can result from weak spark due to faulty components like plugs, coils, coil wires, or distributor caps. Fuel-related culprits, such as clogged injectors or issues in the PCM or wiring, are also mentioned. Serious internal engine problems like valve sealing, worn cam lobes, or broken valve springs are considered more severe possibilities.

Systematic Troubleshooting

The article advises eliminating simpler possibilities first, such as verifying spark strength and checking for fuel and vacuum leaks using a propane test. Swapping plugs and coils aids in identifying if the misfire transfers to another cylinder. Additionally, a methodical approach to diagnosing specific cylinder misfires is suggested, focusing on gathering information, testing, and measuring before replacing or repairing confirmed faulty components.

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