Is Cylinder Deactivation Harmful to Your Engine? Provided by Scion
The advantages of cylinder deactivation systems are clear: According to estimates from the U.S. Department of Energy, they can enhance fuel efficiency by approximately 7.5 percent. (Many car manufacturers boasting cylinder deactivation systems claim efficiency gains of up to 20 percent.) However, some drivers are skeptical about whether this technology consumes unnecessary fuel or induces inefficiencies during activities such as highway cruising and local driving.
So, what exactly is this fuel-saving technique, and should you be concerned about it?
Understanding Cylinder Deactivation
Cylinder deactivation involves temporarily shutting down specific cylinders during low-demand driving scenarios to conserve fuel. This process effectively reduces the engine’s capacity, thereby improving fuel efficiency. Nonetheless, since pistons undergo several thousand cycles per minute, halting them at any given moment requires effort.
The most common method employed is to cease fuel injection and close the intake and exhaust valves for the desired cylinders. Although this may sound straightforward in theory, it is far from simple in practice, as most engines utilize a camshaft to operate valves, lacking inherent variability. Mazda, a pioneer in developing cylinder deactivation for a four-cylinder engine, circumvented this obstacle by integrating a switch into the hydraulic valve adjusters. When activated, it alters the pivot point of the rocker arm, preventing valve movement. You can witness this system in action through a video demonstration.
Diesel engines can also employ cylinder deactivation, albeit for different purposes. Their objective is to elevate exhaust temperatures to enhance the cleansing of hydrocarbons emitted during fuel combustion. Catalytic converters function more effectively when operating at higher temperatures. Running on fewer cylinders necessitates the remaining pistons to work harder to compensate for the power loss, thereby generating increased heat. Although diesel engines deliver superior fuel efficiency compared to gasoline-powered vehicles, their emissions are substantially dirtier than those emitted by an equivalent gasoline vehicle.
Customer Concerns
Before delving further, it’s essential to clarify that we have not come across any recalls linking cylinder deactivation (CDA) to excessive engine wear and tear. Below are the only marginally related recalls we identified:
In a recent instance in 2024, Mercedes recalled specific sedans, including 26,200 Mercedes- and Maybach-manufactured S580 sedans from the 2021-2023 model years, due to issues with its Camtronic cylinder deactivation technology. The German automaker identified that in the event of a hardware malfunction within its CDA system, the fuel injectors might erroneously dispense excess fuel into the engine, raising exhaust temperatures. While not critical, this could potentially lead to catalytic converter damage and engine stalling in extreme circumstances.
Further back, Mazda’s CX-5 garnered attention for problems with its cylinder deactivation (CDA) system. Several Mazda vehicles were recalled because the
Americans were pioneers of cylinder deactivation technology back in 1981 when Cadillac introduced the “Modular Displacement” system. This system boasted a potential 15% increase in fuel efficiency. Unlike current systems that disable half of the cylinders, Cadillac’s V-8-6-4 system could dynamically switch between running on eight, six, or four cylinders depending on the engine load. The system featured an MPG sentinel gauge on the dashboard to show the number of cylinders in use. Despite its advanced features, the system faced issues such as lurching and hesitation during cylinder count changes.
Cadillac persevered, releasing 13 software updates to enhance drivability. However, the system was eventually discontinued after just one model year due to persistent flaws. Looking ahead, the future of technology like cylinder deactivation remains uncertain, especially with the rise of electric vehicles potentially delaying its widespread adoption. Nonetheless, continuous advancements and learnings from past failures will drive improvements in this technology.
