#3 – Poor Gas MileageĪs already mentioned, one of the benefits of variable valve timing is an increase in fuel economy. When that power isn’t there, there’s not much you can do. While you may think this isn’t that big of a deal, there may be times where you need to floor it to prevent an accident. Power to accelerate quickly and/or climb hills will be lacking. The engine will accelerate more slowly than normal. But with a faulty oil control valve or VVT solenoid, excess engine oil may be introduced into the VVT system which can result in rough idling, stalling, or just poor engine running in general. Under normal conditions, the VVT system activates at higher RPMs or when under load bearing conditions such as driving up a hill. When it does, any or all of these symptoms can alert you to problems: #1 – Rough Idle The VVT solenoid and OCV comprise an integrated unit. See Also: Advantages of Variable Valve Timing (VVT) Bad Oil Control Valve Symptoms The OCV directs a continuous flow of oil to the timing chain and associated sprockets increasing lubrication and cooling oil flow to these parts. There is a secondary benefit to this system. This activity occurs almost instantly and is invisible to the driver. When the engine reaches a steady speed, the OCV closes and the cams return to their initial positions. The cam position can be advanced or retarded depending on the engine speed and throttle (gas pedal) position. When this valve opens, oil under pressure flows to the cam control mechanism quickly changing cam position with respect to the driving chain or belt. Signaled by the ECU (electronic control unit), the variable valve timing solenoid opens its integral oil control valve. You are stopped at an intersection or just cruising along and you step on the gas. These systems utilize the readily available oil flow from the engine lubrication system to do the work. In most modern automobiles engines, varying the valve timing is done by cam control mechanisms that alter cam position with respect to the engine crankshaft. Related: 5 Symptoms of a Bad Cam Phaser What is an Oil Control Valve (and How Does It Work?) And beyond just performance and fuel economy benefits, VCT has been found to help reduce vehicle emissions such as oxides of nitrogen. Today virtually all automobile builders have jumped on board the VCT train. This system incorporated the first use of a cam mid-position lock to hold the cams at a center setting when no advance or retard was required. Variable cam timing also began to see wide acceptance in motorcycle engines in the early 2000s.īorg Warner recently developed a VCT system for the 2016 Hyundai Lambda II engine series. Porsche introduced it with the VarioCam in the V8-powered 928 model.

Honda incorporated this in their VTEC engines in 1989. Gradually, variable cam timing began to catch on. This one change greatly benefitted this small Alfa engine. The effect of this mechanism was to add mid-range power. The design was very basic and provided intake valve retardation as engine speed increased. This feature came standard on the 2.0L fuel injected engine in the 1980 Spider. Engineers reasoned that varying the valve operation as engine speed changes could offer both performance and fuel economy benefits.Īlfa Romeo was the first manufacturer to offer VCT on a production automobile. Patents for such systems on early engines date as far back as the 1920s. This concept introduced cam timing that varied around a predetermined pattern of valve operation. Then variable cam timing (VCT) came along.

Can You Drive With a Faulty Oil Control Valve?.

What Causes the VVT Solenoid and OCV to Go Bad?.

What is an Oil Control Valve (and How Does It Work?).

Valve timing was set to to achieve the best performance while yielding acceptable fuel economy. This pattern (called valve timing) was pre-determined and designed into the engine by the manufacturer. The cams in vehicles of decades past provided a fixed pattern of valve operation with respect to the position of the pistons. These camshafts are typically chain or belt driven from the engine crankshaft. There may be as many as four camshafts depending on the engine type in your vehicle.

These valves are pushed open and closed by camshafts. The valves in the engine of your car, SUV or truck operate to control the flow of air, fuel and exhaust gases through the engine combustion chambers. Let’s look at some of the most common symptoms of a bad oil control valve, what causes failure, and how much replacing the VVT solenoid will cost. By optimizing when valves open and close, VVT solenoids boost power and fuel economy. Variable valve timing solenoids (oil control valves) play an important role in engine performance and efficiency. To understand the variable valve timing (VVT) solenoid and associated oil control valve (OCV), it will help to know the history of this device and how it benefits our cars, SUVs and light trucks today.

Intake variable valve timing solenoid