Why does my Toyota Camry's engine hesitate during acceleration?

Engine Hesitation During Acceleration in Toyota Camry (2018-present)

Possible Causes

1. Fuel Delivery Issues: Clogged fuel filters, failing fuel pump, or dirty fuel injectors.
2. Ignition System Problems: Worn spark plugs, faulty ignition coils, or bad wiring.
3. Air Intake Issues: Dirty air filter or malfunctioning mass airflow sensor (MAF).
4. Exhaust Blockages: Clogged catalytic converter or exhaust system.
5. Transmission Problems: Low transmission fluid or transmission issues.
6. Sensor Malfunctions: Throttle position sensor (TPS) or crankshaft position sensor issues.

Step 1: Visual Inspection

• Tools Required: Basic hand tools, flashlight.
• Instructions:
  1. Open the hood and check for any obvious signs of wear or damage (hoses, wiring, etc.).
  2. Inspect the air filter; if dirty, replace it.
  3. Look for any fuel leaks around the fuel injectors and fuel rail.

Step 2: Check for Diagnostic Trouble Codes (DTC)

• Tools Required: OBD-II scanner.
• Instructions:
  1. Connect the OBD-II scanner to the vehicle's diagnostic port.
  2. Read any stored trouble codes and note them for further diagnostics.
  3. If there are codes related to the MAF, TPS, or ignition system, focus on those areas.

Step 3: Fuel System Check

• Tools Required: Fuel pressure gauge, multimeter.
• Instructions:
  1. Fuel Pressure Test: Connect the fuel pressure gauge to the fuel rail.
     • Key on, engine off: Check the fuel pressure against manufacturer specifications (around 40-50 psi typically).
     • If low, check the fuel pump and fuel filter.
  2. Injector Function: Use a multimeter to check the resistance of the fuel injectors (should be within 12-16 ohms). If outside this range, replace the injector(s).

Step 4: Ignition System Inspection

• Tools Required: Spark plug socket, ignition coil tester.
• Instructions:
  1. Remove and inspect spark plugs for wear and deposits.
     • Replace if the gap is out of spec or if they appear damaged.
  2. Test ignition coils using an ignition coil tester.
     • Replace any faulty coils.

Step 5: Air Intake and MAF Sensor Check

• Tools Required: MAF cleaner, multimeter.
• Instructions:
  1. Remove the MAF sensor and inspect for dirt or contamination.
  2. Clean the MAF sensor using MAF cleaner.
  3. Check the wiring and connector for any signs of damage.
  4. Test the sensor output with a multimeter while running (consult specifications for voltage ranges).

Step 6: Exhaust System Inspection

• Tools Required: Jack and jack stands, exhaust backpressure gauge (optional).
• Instructions:
  1. Inspect the exhaust system visually for any obvious clogs or damage.
  2. Use an exhaust backpressure gauge to check for clogs in the catalytic converter (should be less than 1 psi at idle).

Step 7: Transmission Fluid Check

• Tools Required: Transmission fluid dipstick (if applicable), fluid container.
• Instructions:
  1. Check the transmission fluid level and condition (should be bright red and clean).
  2. If low, add the appropriate type of transmission fluid and retest.

Repair Instructions

1. Fuel System Repair:

   • If the fuel pump is faulty, replace it along with the fuel filter.
   • Clean or replace clogged fuel injectors.

2. Ignition System Repair:

   • Replace worn spark plugs and any faulty ignition coils.

3. MAF Sensor Repair:

   • If cleaning did not resolve issues, consider replacing the MAF sensor.

4. Exhaust System Repair:

   • Replace the catalytic converter if it is found to be clogged.

5. Transmission Repair:

   • If transmission issues are detected, consider having a professional inspect and repair as necessary.

Conclusion

After conducting the diagnostic steps and making the necessary repairs, take the vehicle for a test drive to ensure the hesitation during acceleration has been resolved. If the problem persists, further in-depth diagnostics may be required, possibly focusing on the vehicle's ECU and wiring harness for faults. Always refer to the specific service manual for your Toyota Camry for detailed specifications and procedures.