2003 Acura CLS Manual Misfiring Problem

The 2003 Acura CL-S with manual transmission is known to experience misfiring issues, particularly in the 3.2L V6 engine. Common symptoms include rough idle, loss of power, engine hesitation, check engine light illumination (often codes P0300-P0306), and poor fuel economy. Below are key sections for diagnosis, common causes, troubleshooting steps, repair procedures, and preventive maintenance.

Common Symptoms

Key indicators of misfiring in 2003 Acura CL-S manual transmission:

Diagnostic Trouble Codes

Common OBD-II codes associated with misfiring:

1. P0300 - Random/Multiple Cylinder Misfire Detected
2. P0301 - Cylinder 1 Misfire Detected
3. P0302 - Cylinder 2 Misfire Detected
4. P0303 - Cylinder 3 Misfire Detected
5. P0304 - Cylinder 4 Misfire Detected
6. P0305 - Cylinder 5 Misfire Detected
7. P0306 - Cylinder 6 Misfire Detected
8. P0351 - Ignition Coil A Primary/Secondary Circuit

WARNING! Continuous driving with misfire can damage catalytic converter.

Common Causes

Primary causes of misfiring in 2003 Acura CL-S:

• Ignition System: Faulty spark plugs, ignition coils, or spark plug wires
• Fuel System: Clogged fuel injectors, weak fuel pump, or fuel pressure issues
• Air Intake: Vacuum leaks, dirty air filter, or MAF sensor problems
• Compression: Worn piston rings, valve issues, or head gasket failure
• Electrical: Bad crankshaft position sensor or camshaft position sensor
• ECM Issues: Faulty engine control module or wiring harness problems

Troubleshooting Steps

Systematic approach to diagnose misfiring:

1. Scan for trouble codes using OBD-II scanner
2. Perform visual inspection of ignition components
3. Check spark plug condition and gap (should be 0.039-0.043 inches)
4. Test ignition coil resistance (primary: 0.6-0.8 ohms, secondary: 12-16k ohms)
5. Inspect fuel injectors for proper operation and spray pattern
6. Check fuel pressure (should be 45-50 psi at idle)
7. Perform compression test (should be 150-180 psi, within 15% variation)
8. Inspect for vacuum leaks using smoke machine or carb cleaner
9. Check MAF sensor readings and clean if necessary

CAUTION! Disconnect battery before working on electrical components.

Repair Procedures

Step-by-step repair instructions:

Spark Plug Replacement:

1. Disconnect negative battery cable
2. Remove engine cover and ignition coil connectors
3. Remove ignition coils using 10mm socket
4. Remove old spark plugs with spark plug socket
5. Gap new plugs to 0.041 inches
6. Install new plugs and torque to 13 lb-ft
7. Reinstall coils and connectors

Ignition Coil Replacement:

1. Identify faulty coil using diagnostic codes
2. Disconnect electrical connector
3. Remove mounting bolt
4. Pull coil straight out from spark plug well
5. Install new coil and reconnect

Parts Replacement

Recommended replacement parts and intervals:

Preventive Maintenance

To prevent misfiring issues:

1. Follow recommended spark plug replacement schedule
2. Use high-quality premium fuel
3. Replace fuel filter regularly
4. Keep air intake system clean
5. Use OEM or high-quality aftermarket parts
6. Address check engine lights promptly
7. Perform regular tune-ups

Tip: Use fuel injector cleaner every 10,000 miles.

Technical Specifications

• Engine: 3.2L J32A2 V6
• Horsepower: 260 hp @ 6100 rpm
• Torque: 232 lb-ft @ 3500-5500 rpm
• Compression Ratio: 10.5:1
• Fuel System: Programmed Fuel Injection (PGM-FI)
• Ignition System: Direct ignition system with individual coils
• Spark Plug Gap: 0.039-0.043 inches (1.0-1.1 mm)
• Fuel Pressure: 45-50 psi at idle

Safety Precautions

Always follow safety procedures when working on misfiring issues:

WARNING! Engine components can be extremely hot. Allow engine to cool before working. Disconnect battery to prevent electrical shocks. Use jack stands when working under vehicle. Work in well-ventilated area when testing fuel system.

Professional Service

When to seek professional help:

1. If misfiring continues after basic component replacement
2. When compression test shows significant variation between cylinders
3. For ECM or wiring harness diagnosis
4. If catalytic converter damage is suspected
5. For complex fuel system repairs

Recommended Service: Acura dealership or certified import specialist.

FAQ & Support

Technical Support: Acura Customer Service: 1-800-382-2238

Online Resources: Acura Owners Portal and Acura CL enthusiast forums