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Honda can't sell lean-burn in California

Honda Motor Co. Ltd. will not be able to sell its touted 1.5L lean-burn 4-cyl. engine with variable valve timing (VVT) in California this fall because it exceeds the state's emissions standard for oxides of nitrogen (NOx) of 0.4 grams per mile (gpm). Instead, the 1992 California Civic VX will feature a version of the VVT engine with conventional 3-way catalyst control.

The Civic with the fuel-efficient learn-system engine will arrive in 49-state Honda dealers in October. The Honda lean-system engine operates at air/fuel ratios believed to be a high as 25:1 during "normal operation" and switches to 3-way catalyst control during the "powermode" with NOx controlled by exhaust-gas recirculation during "transition," says a Honda spokesman.

"We are pursuing technology we hope will permit the lean engine to comply with current California and next-generation federal NOx standards and didn't want to withhold the new engine's advantages from the market in the meantime," he says.


Automotive industry engineers tell Ward's Auto World that Honda likely is betting on successful development of a lean-system catalyst, possibly the copperzeolite type, in combination with further fine-tuning of the system to meet the standard.

Mitsubishi Motors Corp, (MMC) also will offer a production car this fall in Japan equipped with a 1.5L lean-system 4-cyl. engine, while Honda will offer a lean-burn engine in its 1992 Civic for sale both in Japan and North America.

The Honda announcement, however, was more surprising. MMC, along with Toyotat Motor Corp., said earlier this year that they expected to have lean-system engines in production this fall. Mazda Motor Corp. also say it's at work on a lean-system engine for '95 model cars.

Although much of the U.S. press touts the "leanburn" engines as new developments, Richard M. Donnelly, General Motors Corp. vice president and head of the company's powertrain division, says the concept has been around since the mid-1930s.

"The basic problem with this technique is that it generates greater amounts of oxides of nitrogen and is suitable only for very small engines and very light cars," he says.

At the heart of the Honda system, and the learn-system engine also recently announced by Mitsubishi, is a lear enhaustgas oxygen sensor like the unit made by NGK Spark Plug Co., Ltd.

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