The NHTSA is Investigating Nissan's Variable Compression Engine Problems

by Chris Teague

Published: December 19th, 2023

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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Chris Teague

Chris grew up in, under, and around cars, but took the long way around to becoming an automotive writer. After a career in technology consulting and a trip through business school, Chris began writing about the automotive industry as a way to reconnect with his passion and get behind the wheel of a new car every week. He focuses on taking complex industry stories and making them digestible by any reader. Just don’t expect him to stay away from high-mileage Porsches.

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3 of 48 comments

Sobhuza Trooper on Dec 19, 2023

"...but more complication isn’t always a good thing in mechanical systems."

"...but more complication is never, ever a good thing in mechanical systems, no exceptions."

FIFY

1 Reply
- Zerofoo on Dec 20, 2023
  
  One of my engineering professors wisely told me "complexity is the enemy of reliability".
  
  2
E on Dec 19, 2023

When I first saw a description of these engines I wondered how Nissan had made such a complex design reliable enough for mass production. Guess it turns out they didn’t. I am surprised the tech didn’t provide more efficiency benefits.

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