my Toyota Highlander Third Generation (2014-2019) engine misfires when accelerating what's wrong

Toyota Highlander Third Generation (2014-2019)

Error Codes

2-4 hours

Time

medium

Difficulty

high

Severity

3 min read

560 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 engine misfires during acceleration in Toyota Highlander 2014-2019. Step-by-step guide with diagnostic procedures and repair instructions.

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 performing any maintenance to avoid burns.

Symptoms

•Engine misfire during acceleration
•Rough idle when the engine is running
•Decreased engine power or responsiveness
•Check engine light illuminated
•Poor fuel economy
•Increased exhaust emissions

Diagnostic Steps

1
Scan the vehicle's computer system for any error codes using an OBD-II scanner.
2
Inspect the spark plugs for wear, fouling, or damage.
3
Check ignition coils for proper operation and signs of failure.
4
Examine fuel injectors for clogs or malfunctions.
5
Test fuel pressure to ensure it meets manufacturer specifications.
6
Inspect air intake system for blockages or leaks.

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
•Spark plug socket
•Ratchet and socket set
•Multimeter
•Fuel pressure gauge
•Ultrasonic cleaner (optional)

Parts Required

•Spark plugs
•Ignition coils (if necessary)
•Fuel injectors (if necessary)

Related Faults

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Diagnostic Steps

1
Scan the vehicle's computer system for any error codes using an OBD-II scanner.
2
Inspect the spark plugs for wear, fouling, or damage.
3
Check ignition coils for proper operation and signs of failure.
4
Examine fuel injectors for clogs or malfunctions.
5
Test fuel pressure to ensure it meets manufacturer specifications.
6
Inspect air intake system for blockages or leaks.

Solution

1. Preparation

Gather tools and parts required for the repair.
Ensure the vehicle is parked on a flat surface, and the engine is cool.
Disconnect the negative battery terminal to prevent electrical shorts.

2. Replace Spark Plugs

Sub-steps:
1. Remove the engine cover if applicable.
2. Disconnect the electrical connectors from the ignition coils.
3. Unbolt and remove the ignition coils.
4. Use a spark plug socket to remove the spark plugs.
5. Inspect the old spark plugs for condition; replace with new plugs if necessary.
6. Install the new spark plugs to manufacturer torque specifications (typically 13-15 ft-lbs).
7. Reinstall ignition coils and reconnect electrical connectors.

3. Test and Replace Ignition Coils (if necessary)

Sub-steps:
1. Use a multimeter to test the resistance of each ignition coil.
2. If any coil is outside the manufacturer’s specifications, remove and replace it.
3. Follow the same installation procedure as the spark plugs.

4. Clean or Replace Fuel Injectors

Sub-steps:
1. Disconnect the fuel rail and remove the fuel injectors.
2. Use a fuel injector cleaner or ultrasonic cleaner to clean the injectors.
3. If cleaning does not resolve the issue, replace faulty injectors with new ones.
4. Reinstall the fuel rail and reconnect the fuel lines.

5. Check Fuel Pressure

Sub-steps:
1. Connect a fuel pressure gauge to the fuel rail.
2. Turn the ignition key to the "on" position without starting the engine and check the gauge reading.
3. Compare the reading to manufacturer specifications (usually around 50-60 psi).
4. If pressure is low, inspect and replace the fuel pump if needed.