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sluggish based on its design. If you have ever rotated a camshaft by hand, you can visualize the kind of load that the VTC sprocket feels when the engine is running. As the camshaft is opening valves, there is a "backload" on the VTC, but at the closing of the valve, the valvesprings are driving the camshaft forward. The way it loads and unloads the helical piston in the VTC assembly just doesn't really give an opportunity for the piston to be lazy in its position. When the VTC is enabled, the valve at the back of the camshaft is closed off by the VTC solenoid, which directs oil pressure to the face of the helical piston, forcing the piston back against the internal return spring to its stop, thereby advancing the camshaft. With the surface area of that piston and the available oil pressure acting on it, it is going to move to full advancement very rapidly and hold there. At the point the VTC is released, oil pressure is relieved against the face of the helical piston and the internal return spring is going to force the helical piston back to its rest position. If that occurs at the closing event of the valves, it may be sluggish right at that very moment as the camshaft is being driven forward by the valvesprings, which works against the return spring. But once that set of valves have fully seated and the next set of valves are beginning to open, the backload it puts on the sprocket will assist the internal return spring - so to speak - this backload is actually helping to return the piston due to the helical geometry of the VTC mechanism during a valve opening event. I've never come across a Z that indicated to me that the VTCs were behaving sluggishly. When the VTCs are OFF the whole time, bottom end and midrange torque suffer dramatically. Disconnect both of your VTC solenoids and see just how much you lose down low. The only time I've seen a VTC issue affecting performance has been when one of the VTCs were connected to the DET sensor mistakenly since the connectors are the same. Might want to check your connections if you are seeing something odd..
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Are you an enthusiast? If you are out to describe the truth, leave elegance to the tailor.
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