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When it comes to innovations and an amazing driving experience, one system unique to BMW is the VANOS system. This intricate system is able to do what was before impossible. This feature allows driving to feel more smooth, and yet it helps to increase power in your BMW model. However, the one drawback of this amazing part is that when it starts to fail, you will notice the dramatic decline in performance. It is essential to take care of your VANOS system and learn the signs and symptoms of an underperforming system that needs repair.
The VANOS System
The VANOS system is BMW’s take on the variable valve timing unit, or VVT. The VANOS system first came to market in 1992 and revolutionized the way driving felt, increasing engine performance by opening and closing the intake and the exhaust valve reflexively as you drive. This innovation led to smooth idling and increased torque.
The VANOS system is also able to regulate the oil flow to the cam gears via the implementation of solenoids, which makes timing adjustments pin-point accurate. Over the years BMW has released 3 types of VANOS systems. So, depending on the age and model of your BMW, you may have one of the three listed below:
- Single VANOS (1992-2002)
- Double VANOS (1999-2010)
- Double VANOS with Valvetronic (2004-15)
Signs of an Underperforming VANOS System
Overall, a general decline in engine performance and the way that driving feels are the strongest indicators of VANOS trouble. However, this can be narrowed down further into the symptoms listed below:
1. Power and Torque Loss
The main job of the VANOS system is boosting the power and torque the engine is able to produce. So if the VANOS system is failing, this will be noticeably reduced.
2. Hesitation at Low RPM
When the VANOS system is struggling, you are also going to notice that the engine hesitates at low RPM due to the VANOS system not regulating the engine’s timing correctly, meaning that you will notice power loss at lower RPM.
3. Rough Idling
One of the largest selling points of the VANOS system is how smooth it makes driving feel. Therefore, when it starts to decline, you will notice the smoothness of the ride decline also, most notably in the form of rough idling.
4. Lowered Fuel Economy
The VANOS system is designed to keep your engine at peak performance. Without this system working properly, you may recognize that your engine’s efficiency decreases, meaning you will need to visit the pumps more often.
5. Struggling with Cold Starts
In general, starting your car in cold weather can be a challenge, but when the VANOS system fails, this may be even more difficult.
6. Cold Weather Stalling
Similar to the above point, when the weather is cold and your VANOS system is failing, you are going to experience an increased rate of stalling, and in general, your engine will feel uncooperative.
7. Fault Codes
Your BMW’s onboard computer will trigger fault codes when it detects a VANOS issue. Sometimes, this will even trigger the illumination of the check engine light.
8. Limp Engine Post Acceleration
Acceleration requires your engine to work extra hard, and this can put a strain upon it. The VANOS system is able to help regulate this through timing, so accelerating and decelerating are less stressful for your engine, and therefore, both processes feel much smoother. However, without this, the engine will not be able to regulate. This means that you might notice a steep drop off in power after you accelerate, leaving you with an engine that feels limp. This could potentially be dangerous in front of traffic.
Hayes European
Residents of Santa Cruz, Aptos, Soquel, and 
Capitola, CA need not put up with the annoyances of VANOS failure. Hayes European provides speedy repairs at an affordable price when failures occur. We also perform regularly-scheduled maintenance with our expert team of BMW specialists. You can count on us to become your trusted BMW repair and maintenance shop. Call us today for an appointment or stop by to speak with one of our trained technicians about any problem or maintenance issue. We look forward to meeting you.