Can a Bad VVT Solenoid Cause a No-Start Problem in Your Car?

Variable valve timing is a widely used technology by modern engine manufacturers. In the old days, car manufacturers designed engines to adjust the valve lash and the ignition timing manually. Variable valve timing, or VVT as commonly referred to, revolutionized the way engines work. The technology helped make engines more effective in fuel efficiency, exhaust emissions, and general performance.

No-start problems highlights

• DIY repairs:possible but complicated
• Tools needed:basictools set
• Commonreasons:battery issues, wiring problems, bad connections, electronic unit failure
• Time to repair:0.5 - 3 hours
• Price for parts:$100 - $450
• Can you drive?Obviously, no
• Alternative solutions:jump-starting, starter shorting, tow-truck

Understanding the Variable Valve Timing

Inside an internal combustion engine are valves that are used to control the flow of exhaust gases and intake components in and out of the combustion chamber. The engine's performance is highly determined by the valves' timing, duration, and lift. All engines have similar valve timing, and VVT comes in to make a difference.

In a car engine, there are valves that are attached and driven by camshafts. The timing of the valve's lift in relation to the position of the crankshaft is highly important in determining the amount of energy the engine produces. The crankshaft drives the camshaft, which then determines the valves' lift and the duration. The crankshaft drives the camshaft using the timing chain, timing belt, or gears.

In a nutshell, a variable valve timing system determines and controls:

• Valve timing
• Valve duration
• Valve lift

This means that with the VVT, the position of the camshaft can be adjusted, thereby altering valve timing. Several components are in play for this mechanism to work, among them the actuator, which is hydraulically controlled. The actuator retards or advances the valve's timing.  

What is a VVT solenoid?

A variable valve timing solenoid typically applies oil pressure to activate the VVT mechanism and adjust its timing. The car's powertrain control module (PCM) or the Engine Control Unit (ECU) controls the solenoids, which then activate the actuator located at the end of the camshaft.

Though every car manufacturer has its unique VVT system, most systems use variable valve timing solenoids to control how the VVT system works. The system of how the VVT solenoid works is similar, even though using different acronyms. Toyota uses VVT-I and VVTL-I, Audi uses Valvelift, BMW uses VANOS, Ford uses Ti-VCT/VC, and Hyundai, Volvo, and KIA use CVVT.

How does the VVT solenoid work?

The ECU, the PCM, or the car's computer, as many people refer, gives the variable valve timing solenoid directions. The solenoid works using oil pressure, and this is how it alters the rotation of the camshaft.

There are conduits that lead to the camshaft-phasers and which are controlled by oil flow from the solenoid. Depending on the message the conduits get, they can delay or hasten the intake valve opening. Every conduit receives a separate message from the solenoid.

This then means the valves open and close based on the message the conduits get from the solenoid every time. The variation of the intake pressure is then used by the PCM to optimize fuel delivery in the combustion chambers.

What are the symptoms of a bad VVT solenoid, and is no-start one of them?

The VVT system heavily relies on the VVT solenoid working optimally. Whenever the solenoid malfunctions, all manner of problems can arise. Disruptions in the way the timing chain and gears work. Here are some of the tell-tale symptoms of a bad VVT solenoid;

• Dirty engine oil

The VVT solenoid works best when the engine oil is clean. When the oil has debris or has lost some of its viscosity and lubricity, the solenoid can start developing problems. When the engine oil has a lot of debris and impurities, it loses its viscosity, leading to the clogging of the solenoid. This clogging further causes the gear and the chain to clog. Dirty oil is more of a cause than a symptom of a malfunctioning VVT solenoid.

To avoid this problem, you should change the engine oil as the manufacturer of the vehicle has recommended. Remember also that very low oil levels may cause solenoid problems. Regularly open the car's hood and check the oil levels before you start your car in the morning.

• Check engine light ON.

The car manufacturer of your vehicle has installed an Engine Control Unit (ECU) and a powertrain control module (PCM) which alert you whenever there is a problem. The VVT solenoid gets its signal from the ECU or the PCM, depending on the make of your car. When the solenoid is not working properly, the ECU generates an error code and transmits this message to the driver via the check engine light (CEL).

When the check engine light comes on, it is time to use a diagnostic machine to tell you what the problem is. Depending on your car's make and model, you will get a specific error code for a faulty VVT solenoid. Your mechanic should know the necessary steps to take to correct this problem.

• Decreased fuel economy

The variable valve timing solenoid is a primary player in ensuring the system works efficiently. The valves closing and opening at the right time ensures that combustion happens right without wasting fuel. A malfunctioning solenoid will most likely lead to poor fuel efficiency.

If you see the check engine light and realize that the car is consuming more fuel than normal, it is time to visit a mechanic to check the car. The diagnostic machine will give a solenoid code error if it's the one malfunctioning. Though there are many other reasons why fuel economy can drastically go down in your vehicle, checking with the diagnostic machine is the surest way to catch the problem before it escalates.

• Rough idling

The VVT system is designed such that it only comes alive at higher RPMs or some load is packed in the car. The VVT system will also kick in when the car is driving uphill. When the solenoid goes bad, excessive oil will be introduced to the VVT gears, and this causes the engine to have idle rough. You will notice the RPM fluctuating whenever the VVT system is activated.

The rough idling of the engine can cause some components to wear out prematurely. Combined with other symptoms, pointing the trouble to the VVT solenoid should be easy.

• Misfiring when under heavy load

Another symptom of a failing VVT solenoid is engine misfiring. This happens especially when the car is under heavy load. The problem comes about because the combustion of the fuel is incomplete.

How to fix a bad VVT solenoid

When you discover that the solenoid is the problem, it is advisable to replace it immediately. You should take your vehicle to a professional mechanic, but you can also replace the solenoid at home. If you plan to replace the solenoid yourself, you will need a long list of tools and accessories, such as the user manual. Failure to fix a faulty VVT solenoid can lead to increased wear and tear of engine parts, and the fuel economy will keep worsening.

Check with your dealer and user manual whether the VVT solenoid failure is covered under warranty. The best bet when it comes to the replacement of the solenoid is sourcing from the car's manufacturer. However, some good aftermarket solenoids even give the manufacturer ones a run for their money. Consult your mechanic on the best replacement solenoid to install in your car.

Conclusion

A bad VVT solenoid can cause all manner of trouble in your car. Even though you can continue driving your car, you will be subjecting it to further damage. Some of the VVT components that can spoil due to driving using a bad solenoid is the actuator.

Driving your car with a spoilt VVT solenoid is, therefore, a sure way to attract a huge bill from the service center since it is not only the solenoid that will need to be replaced.

As observed above, a bad VVT solenoid will come with all manner of symptoms safe for no-start. The vehicle not starting has not been attributed to a bad solenoid. This is because the VVT solenoid comes into play after the engine has come to life. This means that the solenoid does not interfere with how the ignition works.

As noted earlier, a bad solenoid will cause rough idling but will not make your car fail to start. It is worth noting, however, that continued use of your vehicle while its solenoid is malfunctioning can lead to further damage to engine components. These components might be vital in the starting of the car. Timely fixing of a bad VVT solenoid prevents further damage to other engine parts, which might lead to the car stalling or even not starting.