In the early to mid-1960's, American automotive giants Chrysler, Ford, and General Motors ruled the streets and drag strips across the land. With every new car produced, the "Big Three" learned more about engine performance and how to squeeze every ounce of horsepower out of their engines by manually adjusting valve lash and ignition timing. One of the biggest breakthroughs was the development of variable valve timing (VVT), a new system that utilized advanced (for the time) electronic technology to apply variable electronic signals from the ignition system by way of a variable valve timing solenoid. Today, a VVT system can be found in virtually all production vehicles sold throughout the United States.

Each automotive manufacturer has their own unique VVT system, but most of them rely on a fully functional variable valve timing solenoid to control the flow of oil to the VVT system as it is engaged. This system typically activates when there is a significant load against the engine. Some examples of this include while a vehicle is carrying additional weight, traveling up hills, or when acceleration is expedited through throttle control. When the VVT solenoid activates, oil is sent to lubricate the variable valve timing chain and gear assembly. If the VVT solenoid fails or is blocked, the lack of proper lubrication can cause the timing chain and gear to prematurely wear or break entirely.

There are several other problems that may occur when a VVT solenoid is wearing out or has broken that may extend to complete engine failure. In order to reduce the potential of these serious situations occurring, listed below are a few warning signs to be aware of that might indicate a problem with the VVT solenoid. Here are a few symptoms of a worn out or broken VVT solenoid.

1. Check Engine Light comes on

Since today's modern cars are controlled by an Engine Control Unit (ECU), virtually all individual components are monitored by the ECU. When one part is beginning to fail, the ECU will store a specific trouble code that will let a mechanic using a scan tool know that a problem exists. Once the code has been generated, it will signal the driver by illuminating a specific zone warning. The most common light to illuminate when a VVT solenoid is failing is the Check Engine Light.

Due to the fact that every automotive manufacturer has different codes they utilize, it's critical for a car owner to contact a local ASE Certified mechanic to inspect the car, download the code through the correct diagnostic tool and determine the precise source of the problem. In fact, there are literally dozens of individual codes for VVT solenoid issues for every automotive manufacturer. Once the mechanic has this initial information, they can begin to resolve the specific issue.

2. Engine oil is dirty

This is more of a cause as opposed to a symptom. The VVT solenoid works best when the engine oil is clean, free of debris, or has lost some of its lubricity or viscosity. When the engine oil becomes clogged with debris, dirt or other foreign particles, it tends to clog up the passageway from the solenoid to the VVT chain and gear. If your engine oil has not been changed out on schedule, it could damage the VVT solenoid, the VVT chain, and the gear drive.

To avoid this situation, make sure to have your engine oil changed as recommended by the vehicle manufacture. Low oil levels can also cause problems with the VVT solenoid and other timing system components.

3. Rough engine idle

Typically the VVT system does not activate until the engine is at higher RPM or is introduced to load bearing situations like driving uphill. However, if the VVT solenoid is malfunctioning, it is possible that it will introduce additional engine oil to the VVT gears. This can cause the engine to idle rough, specifically the engine RPM to fluctuate as the system is activated. If not checked quickly, it can cause additional engine components to wear prematurely. If your engine idle is rough, make sure to have a certified mechanic inspect this as soon as possible.

4. Decrease in fuel economy

The purpose of variable valve timing is to ensure that the valves open and close at the right time to maximize engine performance and reduce fuel consumption. When the VVT solenoid is malfunctioning, the entire system can be compromised, which may result in intake and exhaust valves opening and closing at the wrong time. This typically causes the fuel economy to drastically reduce.

If you recognize any of the above warning signs of a bad or failing variable valve timing solenoid, contact a local ASE certified mechanic from YourMechanic. They can inspect your vehicle, replace the variable valve timing solenoid if needed, and keep your car or truck running strong.

This article originally appeared on YourMechanic.com as Symptoms of a Bad or Failing Variable Valve Timing (VVT) Solenoid and was authored by Timothy Charlet.


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