How to Keep Your Engine Running Smoothly: 5 Uncommon Checks

The expert tip

• Inspect the serpentine belt for cracks, glazing, or missing ribs every 30,000 miles or 3 years; a slipping belt can cause erratic accessory operation and rough running.
• Clean the mass airflow sensor with dedicated MAF cleaner every 15,000 miles; a dirty sensor skews fuel trims and causes hesitation.
• Replace the PCV valve every 30,000 miles; a clogged valve builds crankcase pressure and leads to oil leaks and rough idle.
• Check the engine coolant temperature sensor resistance when the engine is cold (should be around 2,000 to 3,000 ohms at 20°C); a faulty sensor makes the ECU run the engine rich.
• Test the ignition coil resistance with a multimeter; primary resistance is typically 0.5 to 2 ohms, secondary 5,000 to 15,000 ohms; replace any coil that is out of spec.
• Use a vacuum gauge to check for intake leaks; at idle, a steady reading of 17 to 22 inHg indicates good engine health; lower or fluctuating readings point to a leak or mechanical issue.