🚨 Diagnostic Profile
Vehicle Make: Acura
Technical Description: Cylinder 2 Misfire (commonly stored as P0302)
This code indicates that the Powertrain Control Module (PCM) has detected a misfire event specifically occurring in cylinder number 2. A misfire happens when the air-fuel mixture in the cylinder fails to ignite properly or completely, causing incomplete combustion. This can result in rough idling, hesitation during acceleration, reduced fuel economy, and if left unaddressed, potential damage to the catalytic converter due to unburned fuel entering the exhaust system.
🚨 Repair Difficulty Tier
Difficulty Rating: [Intermediate]
Diagnosing a cylinder-specific misfire on an Acura requires the use of an OBD-II scan tool capable of reading live data streams (such as misfire counters and fuel trims), along with a basic understanding of ignition and fuel delivery systems. While replacing components like spark plugs or ignition coils is mechanically straightforward, accurately isolating the root cause (ignition, fuel, or mechanical) demands methodical testing with a multimeter or scan tool. No specialized module programming is typically required unless the PCM itself needs reprogramming after repeated misfire-related fault storage.
🛠️ Resolution Steps
Step 1: Preliminary Inspection
- Visually inspect the ignition coil and spark plug wiring for cylinder 2, checking for cracks, corrosion, or loose connections.
- Remove the spark plug from cylinder 2 and inspect its condition—look for fouling, oil deposits, or excessive electrode wear.
- Check the vacuum lines and intake manifold gasket near cylinder 2 for any visible leaks that could cause a lean misfire condition.
- Inspect the wiring harness connector at the coil pack for signs of heat damage or pin corrosion.
Step 2: Diagnostic Verification
- Connect an OBD-II scan tool and review live data for Cylinder 2 Misfire Counts, Short-Term Fuel Trim (STFT), and Long-Term Fuel Trim (LTFT) values.
- Perform a coil swap test—switch the ignition coil from cylinder 2 with a neighboring cylinder to see if the misfire follows the coil or stays with the cylinder.
- Use a multimeter to check the resistance of the fuel injector for cylinder 2 and compare it to manufacturer specifications.
- If available, perform a compression or leak-down test on cylinder 2 to rule out mechanical issues such as a burnt valve or worn piston rings.
Step 3: Resolution & Reset Process
- Replace the spark plug and/or ignition coil for cylinder 2 if testing confirms an ignition-related fault.
- If the fuel injector is found to be out of spec, replace it and clear any stored fuel trim adaptations.
- Repair or replace any damaged wiring harness sections or connectors identified during inspection.
- Clear the Diagnostic Trouble Codes (DTCs) using the scan tool and perform a test drive to confirm the misfire does not return.
- Recheck live data after the reset to verify fuel trims have stabilized and no new misfire counts are being recorded.
📦 Parts, Labor, and Budget Estimates
Required Components/Software: Ignition coil (cylinder 2), spark plug set, fuel injector (if applicable), OBD-II scan tool with live data capability, digital multimeter.
Average Component Price: $25–$150 (spark plugs and ignition coil combined); $80–$200 (fuel injector, if replacement is needed).
Estimated Labor Hours: 0.5–1.5 hours for diagnostic verification; an additional 0.5–1.0 hour for component replacement, depending on engine layout and accessibility.