how to fix a misfire in my Toyota Corolla E170 (2013-2019)

Toyota Corolla E170 (2013-2019)

Error Codes

2-4 hours

Time

medium

Difficulty

high

Severity

Error Code: P0301, P0302

3 min read

592 words

⚠️ Safety Warning

This issue requires immediate attention. If you are not experienced with automotive repairs, consult a professional mechanic. Working on critical systems can be dangerous.

Problem Statement

Learn how to diagnose and fix P0301, P0302 engine misfire in Toyota Corolla E170 (2013-2019). Step-by-step guide with diagnostic procedures and repair instructions.

Error Code

P0301, P0302

Affected Component

Engine

Estimated Time

2-4 hours

⚠️ Safety Warnings

Important safety information - read before proceeding

•Disconnect the battery before working on electrical components
•Allow the engine to cool before working on it to avoid burns

Symptoms

•Check engine light illuminated
•Rough idle
•Engine stalling during acceleration
•Decreased fuel efficiency
•Unusual exhaust emissions
•Engine vibrations felt through the cabin

Diagnostic Steps

1
Scan for error codes using an OBD-II scanner to identify specific misfire codes
2
Inspect spark plugs for wear or fouling and check for proper gap
3
Check ignition coils for proper operation and signs of damage
4
Test fuel injectors for proper spray pattern and functionality
5
Verify the condition of air and fuel filters for clogs
6
Inspect vacuum lines for leaks that could affect air-fuel mixture

Solution

💡 Expert Tip

For complex repairs like this, consider taking photos at each step. This helps if you need to reverse a step or consult with a mechanic. Also, keep all removed parts organized - you may need to reference them during reassembly.

Verification

After completing the repair, verify that the issue has been resolved:

✓Test the affected component to ensure it functions correctly
✓Check for any error codes or warning lights
✓Monitor the vehicle for a few days to ensure the issue does not recur

Prevention Tips

To prevent this issue from occurring again:

•Follow the manufacturer's recommended maintenance schedule
•Address warning signs early before they develop into major issues
•Use quality parts and fluids recommended for your vehicle
•Keep detailed records of all repairs and maintenance

Tools & Equipment Required

•OBD-II scanner
•Socket set
•Torque wrench
•Multimeter
•Spark plug socket
•Fuel pressure gauge

Parts Required

•Spark plugs
•Ignition coils (if faulty)
•Fuel injectors (if clogged or damaged)
•Vacuum hoses (if cracked)

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Diagnostic Steps

1
Scan for error codes using an OBD-II scanner to identify specific misfire codes
2
Inspect spark plugs for wear or fouling and check for proper gap
3
Check ignition coils for proper operation and signs of damage
4
Test fuel injectors for proper spray pattern and functionality
5
Verify the condition of air and fuel filters for clogs
6
Inspect vacuum lines for leaks that could affect air-fuel mixture

Solution

1. Preparation

Gather necessary tools and parts.
Disconnect the negative battery terminal.
Ensure the vehicle is parked on a level surface and engage the parking brake.

2. Spark Plug Inspection and Replacement

Sub-steps:
1. Remove the engine cover (if necessary) using a socket set.
2. Disconnect the ignition coil connectors.
3. Remove the ignition coils using a socket set.
4. Remove the spark plugs using a spark plug socket.
5. Inspect the spark plugs for wear; replace if they are worn or fouled. Use OEM spark plugs (check the gap specification).
6. Reinstall new spark plugs and torque to manufacturer specifications (typically 13-15 lb-ft).
7. Reinstall ignition coils and reconnect the connectors.

3. Ignition Coil Testing and Replacement

Sub-steps:
1. With the ignition coils removed, check them with a multimeter for resistance according to specifications (typically 0.5 to 1.5 ohms for primary and 10k to 15k ohms for secondary).
2. Replace any ignition coils that are out of specification.
3. Reinstall the new or tested ignition coils and reconnect connectors.

4. Fuel Injector Inspection and Cleaning

Sub-steps:
1. Remove the fuel rail to access fuel injectors (ensure fuel pressure is relieved first).
2. Inspect fuel injectors for clogs or damage.
3. Clean injectors using an appropriate cleaner or replace them if necessary.
4. Reinstall fuel injectors and fuel rail, ensuring proper torque on bolts.

5. Vacuum Leak Inspection

Sub-steps:
1. Visually inspect all vacuum lines for cracks or disconnections.
2. Use a smoke machine or carburetor cleaner to check for leaks around intake manifold gaskets.
3. Repair or replace any damaged vacuum lines or gaskets found.