Signs that your car's Variable Valve Timing (VVT) switch is failing

Article by Christian A., on August 9, 2018

Modern vehicles typically have engines that employ Variable Valve Timing or VVT. Because of VVT, a car can achieve more optimal levels of performance and fuel efficiency at any engine speed. Before VVT was developed, the timing for opening and closing the engine valves was only optimized for a single engine speed. But since engine speeds vary, having a single timing means a decrease in both power and efficiency.

Now, VVT can vary the timing of opening and closing of engine valves for multiple engine speeds. When the engine speeds get higher, inlet valves open earlier to allow more air-fuel mixture to enter the cylinders. At normal driving conditions, VVT isn't activated. But when extra engine work is needed, VVT is activated. Then the information will be relayed from the VVT to the vehicle computer by the Variable Valve Timing (VVT) switch.

However, the VVT switch will wear out or fail. This is usually due to lack of basic maintenance. Once the VVT switch fails, the vehicle won't be able to receive any input from the ECU (engine computer unit) to vary the timing of the opening and closing of the valves according to the situation. As a result, the vehicle may experience a decline in performance as well as a decrease in fuel efficiency.

In order to know whether your car’s VVT switch is failing or has gone bad, here are some signs you can look out for.

Check Engine Light turns on. The Check Engine Light usually illuminates due to many reasons. The ECU produces a number of warning codes that can activate this light. Being an electrical component, the VVT switch is always monitored by the car’s onboard computer. Once the VVT fails to send data or is sending inaccurate data, the onboard computer would sense a possible issue, and the Check Engine Light will turn up. Nonetheless, there are quite a number of engine problems – not just a failing VVT switch -- that may also cause the Check Engine Light to illuminate.

Engine misfires while carry heavy loads or climbing steeps. Of course, there are other signs that may indicate that the VVT switch is failing. For instance, when the car is carrying extra weight, climbing up steeps, or suddenly accelerating, the engine may misfire or trip up just because the VVT switch has failed. Sometimes, the switch isn't the problem but an electrical issue with the switch. If this happens, there might be a chance the engine might sustain some damage.

Engine experiences a rough idle. When the VVT switch is failing, it might not be able to send accurate date to the vehicle computer, and the valve timing won't be adjusted as needed. This could cause the engine to experience a rough idle, especially when the engine speed increases and drops from 100 rpm to 300 rpm at idle.

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Topics: tips, engine

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