The NHTSA is Investigating Nissan's Variable Compression Engine Problems

Nissan hailed its variable compression engines as great for performance and fuel economy, though the real-world benefits of the advanced mills haven’t completely lived up to the hype. They also appear to have issues that could cause a loss of power, knocking sounds, and engine failure in the most extreme cases, leading the National Highway Traffic Safety Administration to open an investigation.

The NHTSA is looking at more than 450,000 Nissan vehicles that use one of its two variable compression engines, including the Altima, Rogue, and Infiniti QX50. Owners have reported all sorts of issues with the 2.0-liter four-cylinder and 1.5-liter three-cylinder engines, but the automaker has not yet issued a recall to address the problems.

Variable compression technology allows the engines to shift their compression ratios to maximize fuel economy or power, depending on the situation. Despite those benefits, Nissan’s engines return only marginally better fuel economy, and the automaker remains the only company using the technology.

Though this is just an investigation at this point, the NHTSA could push for a recall if it determines that there is a defect. The complexity of the engines gives them their notable capabilities, but more complication isn’t always a good thing in mechanical systems. After all, there’s probably a good reason that other automakers haven’t followed Nissan down the variable compression path, and it’s likely because they’re expensive to develop and produce. Their complicated designs could have multiple possible failure points, which is less than desirable for a component that needs to run for tens of thousands of miles.

[Image: Nissan]

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