The 5.7 Hemi engine's Multi-Displacement System (MDS) solenoids play a crucial role in fuel efficiency. When these components fail, they can cause various issues. Let's explore the symptoms of MDS solenoid failure and potential solutions.

Common Symptoms

Engine Misfires

One of the most noticeable signs of MDS solenoid failure is engine misfires. You may experience:

  • Rough idling
  • Loss of power
  • Hesitation during acceleration
  • Check Engine Light illumination

These symptoms occur because faulty solenoids can't properly deactivate or reactivate cylinders, leading to combustion issues.

Ticking Noise

A distinctive ticking sound from the engine, often mistaken for a valve train problem, can indicate MDS solenoid failure. This noise is typically more pronounced when the engine is warm and running at lower RPMs.

Reduced Fuel Economy

Since MDS is designed to improve fuel efficiency, a malfunctioning solenoid can lead to increased fuel consumption. You might notice your vehicle's MPG dropping significantly.

Vibrations

Faulty MDS solenoids can cause noticeable vibrations, especially during highway cruising when the system should be active. These vibrations may feel like a slight shudder or pulse through the vehicle.

Diagnostic Process

To confirm MDS solenoid failure:

  • Use an OBD-II scanner to check for specific error codes
  • Perform a visual inspection of the solenoids and wiring
  • Conduct a pressure test on the MDS system

Solutions

Replacement

The most effective solution is often replacing the faulty MDS solenoids. This typically involves:

  • Removing the intake manifold
  • Locating and removing the old solenoids
  • Installing new OEM or high-quality aftermarket solenoids
  • Reassembling the engine components

System Bypass

Some owners opt to bypass the MDS system entirely. This can be done through:

  • Installing an MDS delete kit
  • Using a tuner to disable the MDS function in the ECU

However, this may affect fuel economy and emissions compliance.

Regular Maintenance

To prevent MDS solenoid failure:

  • Use the recommended oil type and weight
  • Perform regular oil changes
  • Keep the engine clean and well-maintained

FAQs About 5.7 Hemi MDS Solenoid Failure

    • Can I drive with a failed MDS solenoid?
      While possible, it's not recommended as it can lead to increased engine wear and reduced performance.
    • How much does it cost to replace MDS solenoids?
      Costs can vary, but typically range from $500 to $1500, including parts and labor.
    • Will disabling MDS void my warranty?
      It may, depending on your vehicle's warranty terms. Always consult with your dealer before making modifications.

Understanding these symptoms and solutions can help you address MDS solenoid issues promptly, ensuring your 5.7 Hemi engine continues to perform optimally.