why does my Toyota Highlander Third Generation (2014-2019) engine misfire?

Toyota Highlander Third Generation (2014-2019)

Error Codes

2-4 hours

Time

medium

Difficulty

high

Severity

3 min read

554 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 in Toyota Highlander (2014-2019). Step-by-step guide with symptoms, diagnostic steps, and repair instructions.

Affected Component

Engine

Estimated Time

2-4 hours

⚠️ Safety Warnings

Important safety information - read before proceeding

•Disconnect battery before working on electrical systems.
•Allow engine to cool before opening any engine components.

Symptoms

•Check engine light illuminated
•Rough idle or shaking of the vehicle
•Loss of power during acceleration
•Increased fuel consumption
•Engine stalling or hesitation
•Unusual exhaust emissions (e.g., black smoke)

Diagnostic Steps

1
Scan for error codes using an OBD-II scanner to identify specific misfire codes.
2
Inspect spark plugs for wear, damage, or improper gap.
3
Check ignition coils for signs of failure or damage.
4
Verify fuel pressure with a fuel pressure gauge to ensure proper fuel delivery.
5
Inspect air intake system for leaks or blockage.
6
Conduct a compression test on each cylinder to check for mechanical issues.

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
•Torque wrench
•Gapping tool
•Fuel pressure gauge
•Basic hand tools for clamps

Parts Required

•Spark plugs
•Ignition coils (if necessary)
•Fuel filter (if applicable)

Related Faults

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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, damage, or improper gap.
3
Check ignition coils for signs of failure or damage.
4
Verify fuel pressure with a fuel pressure gauge to ensure proper fuel delivery.
5
Inspect air intake system for leaks or blockage.
6
Conduct a compression test on each cylinder to check for mechanical issues.

Solution

1. Preparation

Gather necessary tools and parts.
Disconnect the negative battery terminal to prevent electrical shorts.
Allow the engine to cool before proceeding with any repairs.

2. Replace Spark Plugs

Tools Required: Spark plug socket, ratchet, torque wrench, gapping tool.
Remove the ignition coil cover if applicable.
Remove the ignition coils carefully to access the spark plugs.
Use the spark plug socket to unscrew and remove the old spark plugs.
Check the gap on new spark plugs using the gapping tool and adjust if necessary.
Install new spark plugs, tightening to the manufacturer’s specified torque (usually around 13-15 ft-lbs).
Reinstall the ignition coils and cover.

3. Inspect and Replace Ignition Coils (if needed)

Tools Required: Ratchet and socket set.
Remove the ignition coils from the engine.
Inspect each coil for cracks or signs of arcing.
Replace any faulty coils with new ones, ensuring a proper fit and connection.

4. Check Fuel System

Tools Required: Fuel pressure gauge, safety goggles.
Connect the fuel pressure gauge to the fuel rail.
Turn the ignition to the ON position (without starting the engine) to check pressure.
Compare the reading to the manufacturer’s specifications (typically around 50-60 psi).
If pressure is low, check the fuel pump and fuel filter for clogs or failure.

5. Inspect Air Intake System

Tools Required: Basic hand tools for clamps.
Visually inspect the air intake hoses for cracks or leaks.
Remove and clean the throttle body if necessary, using throttle body cleaner.
Reattach the air intake system securely.