CC Tech: 1979 Volvo 242DL Lambda Sond – Volvo And Bosch Revolutionize Engine Technology

 

The Volvo 200 Series ran for 19 years and 2.8 million cars, and many still consider it the definitive Volvo for its brick-like styling and sensible-shoes dependability. However, its most important legacy lies under the hood: Late-’70s Volvo 240s like this blue 1979 242DL were the first production application of the single most important engine technology of the past 50 years: the three-way catalytic converter with oxygen sensor feedback control.

Since the Volvo 200 Series has gotten a lot of love on Curbside Classic over the years, I’m not going to recap its origins or try to summarize the many minor changes it received over its 19-year history. (For more, start by checking the CC archives for the articles by Volvo veteran Stephen Hansen.) Suffice to say the Volvo 240 was a moderately upscale, very conservative Swedish family sedan and wagon line with a reputation for safety and durability that kept buyers coming back, despite the blocky styling, safe but stolid chassis dynamics, and merely adequate performance and fuel economy.

 

When the four-cylinder 240 arrived in the U.S. for the 1975 model year, it was initially powered by the 2-liter pushrod B20 engine from earlier Volvo cars. (The six-cylinder 260 had the new 90-degree Douvrin V-6, an unhappy Peugeot-Renault-Volvo coproduction.) For 1976, the B20 was replaced in U.S. 240s with the new 2,127 cc overhead cam B21F engine, with an aluminum head, Bosch K-Jetronic mechanical injection, and 102 net horsepower (99 hp in California). Road & Track tested a California-spec 242DL with the four-speed-plus-overdrive manual transmission in April 1976, recording 0 to 60 mph in 13 seconds, a 98 mph top speed, and 21 miles to the U.S. gallon. Like I said — adequate, but only just.

 

Since 1973, however, Volvo engineers had been hard at work on something really new. With urban air pollution growing worse, U.S. federal and California state emissions regulations were becoming progressively more stringent, and U.S. standards were starting to be imitated in other countries, including Japan and Australia. Unlike the early emissions standards of the late 1960s, the latest emissions regulations required simultaneous control of hydrocarbons (HC), carbon monoxide (CO), and oxides of nitrogen (NOx), posing many difficult technical challenges. Volvo turned to West Germany’s Robert Bosch AG, which was then pioneering a revolutionary new emissions control strategy combining a three-way catalyst with “closed-loop” feedback control.

 

The three-way catalytic converter was the holy grail of emissions control, a single-bed catalyst that could simultaneously convert HC, CO, and NOx to CO2, nitrogen, and water vapor. The problem was that making it work required very close control of the engine’s air-fuel ratio — much closer than was practical for a passenger car engine of the ’60s or early ’70s, even with fuel injection. Bosch had a solution: inserting an electronic sensor into the exhaust system to measure the oxygen content of the exhaust, upstream of the catalyst, and then using that data to automatically adjust the engine’s air-fuel ratio in real time, based on actual operating conditions. This made it possible to keep the air-fuel ratio within the catalyst’s “sweet spot,” whether at idle or in stop-and-go traffic.

In 1973, Volvo became the first automaker in the world to begin serious work on adopting this technology for production cars.

 

Early tests involved the latest Bosch L-Jetronic electronic injection system, but Volvo had only just switched from the earlier D-Jetronic to the simpler and more reliable K-Jetronic, and wasn’t keen to switch again. Bosch developed an electromagnetic frequency valve that could vary the fuel metering within the K-Jetronic system in response to signals from the oxygen sensor. Volvo called this system “Lambda-sond”: In engineering-speak, “Lambda” (written with the Greek letter λ) is the term for air-fuel ratio, expressed as a fraction of the ideal stoichiometric ratio, while “sond” is how you say “sensor probe” in Swedish.

 

In November 1974, Volvo delivered a 242DL with a prototype Lambda-sond engine to the EPA for preliminary emissions testing. With its three-way catalyst and feedback control system, it comfortably met federal HC, CO, and NOx standards without the air injection or exhaust gas recirculation systems required on production Volvo cars, and it returned 2.8 mpg better mileage than a standard 1975 Volvo 245 provided for comparison. With some further revisions to the catalyst and spark advance, the Lambda-sond engine could meet California’s more stringent forthcoming HC, CO, and NOx standards while still returning about 5 percent better fuel economy than a 1976 California 240 with air injection and EGR. With some fine-tuning of the sensor and regulator settings, the new system passed the EPA 50,000-mile durability tests and did well in California assembly line testing. The three-way catalyst also didn’t increase sulfuric acid emissions, which was becoming a problem with two-way oxidizing catalysts.

 

Volvo made Lambda-sond and a three-way catalyst standard on California cars for 1977 — the first production cars in the world to be so equipped. Lambda-sond was offered on most U.S. 200 Series models starting in 1978, and it became standard on all U.S. Volvo cars for 1980. The feedback-controlled B21F engine initially had 101 hp and 111 lb-ft of torque (later increased to 107 hp and 114 lb-ft). Volvo claimed it was up to 12 percent more fuel-efficient than the 1976 engine. A 1978 Volvo 242 or 244 sedan with this engine, a manual four-speed, and the optional overdrive also rated up to 24 mg on the contemporary EPA combined scale. Its driveability was good, too, which wasn’t something that could be taken for granted with new cars of this time.

Volvo was very proud of it: Lambda-sond cars started getting their own little grille badges (with the name styled as “Lambda Sond”). Volvo also somehow convinced the U.S. Patent and Trademark Office to let them register “Lambda Sond” (a very generic technical term) as a trademark.

 

Buff book reviewers just shrugged. They were tired of hearing about clean air, and even a racy-looking Volvo 242GT with Lambda-sond had only 101 hp to push 3,000 lb of Brick, which didn’t exactly get the juices flowing. The car magazines were more interested in later adopters of the same Bosch technology, like the Saab 99 Turbo.

 

If they had realized what it would all lead to, the enthusiast magazines would have thrown Volvo a parade. Before the Lambda-sond system, most solutions for meeting tougher emissions standards had come at a heavy cost in performance, driveability, and fuel consumption. Feedback control gave auto engineers an extraordinarily powerful new tool for developing engines that could comply with emissions standards (and remain compliant for 50,000+ miles) while producing more power and better fuel economy, at a time when it seemed like all anyone could expect in future cars was “less” and “worse.”

 

It didn’t happen overnight, or all at once. Performance began to return to U.S.-market production cars in the early ’80s, but it was a gradual process, with some false starts and half-measures. (It took more than a decade before automakers accepted that the best way to integrate feedback control was with digital engine management computers that didn’t need Rube Goldberg electro-mechanical pressure regulators, and that could also provide integrated spark control to create a true self-tuning engine.) However, by the late ’80s, things were definitely getting better, pretty much across the board. By that time, three-way catalysts with feedback control were so ubiquitous that they were taken for granted, but they remained an absolutely indispensable technological foundation of all the reliable, high-tech, emissions-compliant performance engines that have followed.

Volvo didn’t invent this technology (we can thank Bosch for that), but they were the first to do the hard work of applying it to regular production cars in the real world.

 

The rough-around-the-edges 1979 Volvo 242DL pictured above doesn’t look like anything special, and for the most part, it’s not. It wasn’t fast, exciting, or notably luxurious even in 1979. Since Volvo built a total of 2,862,573 nigh-distinguishable 200 Series cars through 1993, with quite a few still on the road, it also can’t be considered particularly rare. Only the most dedicated Volvo fanatic would probably give it a second glance. However, it remains a landmark in the history of production automobiles. The early Lambda-sond Volvos mark the precise point where the tide began to turn — when balancing performance, low emissions, and decent fuel economy went from an impossible dream to a solvable problem. Every modern production car, truck, or crossover with a spark ignition engine owes them a significant debt.

Related Reading

The Volvo 240’s U.S. Journey – Chapter One (by Stephen Hansen)
The Volvo 240’s U.S. Journey – Chapter Two (by Stephen Hansen)
The Volvo 240’s U.S. Journey – Chapter Three (by Stephen Hansen)
Curbside Classic: 1979 Volvo 244 DL – Swedish Sense And Sensibility (by Brendan Sauer)
Curbside Classic: 1978 Volvo 245DL – The Quintessential Volvo (by Tom Klockau)
Curbside Classic: 1982 Volvo 244DL – Best Value Box (by Tom Klockau)
Volvo: A Swedish Perspective (by Ingvar Hallstrom)