What does Cam Phaser Do? Keep reading to find out the work of a Cam Phaser in your car. Almost all late-model cars come with Variable Valve Timing (VVT), which helps to improve engine performance, reduce emissions, and increase fuel economy, depending on the system configuration.

What Does A Cam Phaser Do?

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However, the Camshaft actuators (Camshaft phaser) act as the heart of the VVT system. So, whenever conditions are correct, the phasers alter the position of the camshafts to adjust the engine’s valve timing.

In other words, valve timing has been controlled by a camshaft with carefully calibrated lobes that push the valves open at exactly the right time. Cam phasers control one aspect of this cam timing: the camshaft’s position relative to the crankshaft, and thus the pistons connected to it.

What Does A Cam Phaser Do?

A cam phaser is simply an adjustable camshaft sprocket that can be turned by means of a computer-controlled servo. Instead of just setting a certain number of advance or retard, the computer can advance the cam or cams at low rpm to enhance drivability. And retard the cam or cams at high rpm for more horsepower.

Further, double-overhead-cam engines, with one cam for the intake valves and another for the exhaust, can use these cam phasers to adjust their position relative to each other

 What is a Camshaft Phaser?

As earlier noted, the Camshaft Phaser is more like the heart of the VVT system. Some manufacturers refer to camshaft actuators as phasers, while others use different terms. Not finding what they are called, all phasers serve the same purpose: which is adjusting the position or the “phase” of the camshaft in relation to the crankshaft, thereby altering valve timing.

How the Camshafts and Valves Work

In your car engine, there’s a crankshaft and one or more camshafts. The camshafts open and close a series of valves which lets air (and fuel, in the case of port injection) into the engine and exhaust gases out. While the timing chain (or timing belt) connects the crankshaft to the camshafts.

However, the crankshaft is attached to the connecting rods and pistons. So when the car is running, the valves allow air to penetrate the engine’s cylinders and mix with the fuel. The mixture is ignited by the spark plugs, thereby creating a series of small explosions. Each explosion forces one of the pistons downward inside the engine.

Furthermore, the movement of the pistons makes the crankshaft turn to create the rotational force needed to propel your car down the road.

Also, the timing chain (or timing belt) connects the crankshaft to the camshafts. The shafts must be kept in sync so that the valves open and close at the correct point in the piston’s travel.

How Variable Valve Timing and Phasers Work

Valve timing is fixed, in a traditional engine. However with a modern VVT system, the position of the camshaft (s) can shift, thereby altering valve timing. This feature can improve engine performance, increase fuel economy, or both.

Most cars make use of a hydraulically-operated phaser located at the end of the camshaft – to change the camshaft’s position and retard or advance valve timing. Further, an oil control solenoid applies oil pressure to activate the phaser. While PCM controls the solenoids based on input from various sensors.

Normally, there’s one VVT solenoid for each phaser. Some cars have only a phaser on the exhaust camshaft or the intake camshaft, while others have phasers on both.

What Happens When a Cam Phaser Goes Bad: Three Common Symptoms

Cam phasers are a common issue on many modern vehicles. If your vehicle’s cam phasers begin to fail, you will see the following signs;

Illuminated Check Engine Light

Your car’s engine computer monitors the position of the camshaft through one or more camshaft position sensors. If the module indicates that the camshaft has deviated from its expected position (due to a faulty phaser), the module will switch on the check engine light. And store a diagnostic trouble code in its memory. So, an ab-illuminated check engine light is a common sign of a bad cam phaser.

Poor Engine Performance

A faulty phaser can stop the valve timing from advancing or retarding as needed. As a result, the engine may display performance issues, such as rough running and poor acceleration.

Rattling Noise

Some phasers are designed to lock into position at base idle. But when a phaser is faulty, it may no longer lock into place, which will result in a rattling or knocking sound coming from the top end of the engine. The noise is most noticeable at idle when the engine is hot.

How Much Does it Cost to Replace Cam Phasers?

Replacing cam phasers can be expensive. You can budget from $800 to $2500 to get the job done by a technician. However, the cost will so depend on factors like the mechanic shop, the year, the make, and the model of the vehicle.


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