Sudden Acceleration: The Early Years

Don Sherman
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1957 Dodge Royal Lancer

1957 Dodge Royal Lancer

Tom Hoover, one of the original Ramchargers and the father of the second-generation Hemi V-8 engine, enjoyed his share of excitement during his 24 years as a Chrysler engineer, but a couple of incidents stand out. During the early days of electronic engine controls, Hoover had two brushes with runaway acceleration.

Hoover, now enjoying retirement in Roanoke, Virginia, recently shared his recollections to shed some light on the issue that has plagued practically every maker selling cars and trucks in the US. Today, everything from errant floor mats to magnetic waves from outer space are suggested as the root of all unintended-acceleration evil. But in Hoover’s day, there was only one smoking gun: the Bendix Electrojector fuel injection system that Chrysler planned to introduce on four car lines in the 1958 model year.

Hoover explained, “In 1957, upon graduating from the Chrysler Institute with a master’s degree in automotive engineering, I began my permanent assignment in what was called the Carburetor Lab working on the low-pressure, continuous-flow fuel injection system had been under development there for several years.

“When GM introduced a Rochester Ram Jet fuel injection on the Chevrolet V-8 and a few Pontiac Bonnevilles during the 1957 model year, there was a mad rush for Chrysler to compete. Bendix was further along with the Electrojector system so they brought us a Chrysler New Yorker demonstration vehicle. Our management was impressed by its performance. They elected to go with that system and we immediately began adapting and calibrating it for several Chrysler engines. We had our hands full getting all that work done for a 1958 introduction.”

Bendix, which had extensive experience with fuel injection systems used on Korean-War-era aircraft, commenced work on its Electrojector design in 1951. In many respects it was far ahead of its time, not only with the use of an analog computer to regulate fuel delivery but also because it was a synchronous injection system with each squirt of fuel precisely timed to the opening of the intake valve for all eight cylinders. The key components were eight solenoid-type injectors, a common rail supply of fuel at a regulated 20 psi, several sensors to measure key engine parameters, a commutator added to the ignition distributor to route electrical signals to each injector, and a compact “brain box” to calculate and generate the electric signals needed to operate the injectors. The pulse width of these signals determined how long each injector remained open during each combustion cycle.

Hoover added, “Bendix had been at the cutting edge of military aircraft fuel system design during the final phases of World War II. Ten years later, we were intending to release fuel injection for passenger cars. I was surprised that Bendix, the company that had engineered fuel injection for 18-cylinder B-29s, didn’t have more reliable electronic equipment ready for car applications.

“We soon bumped into what was called electromagnetic interference (EMI) while conducting calibration exercises to improve drivability. One day we were driving past the WJR radio transmitter— located in suburban Detroit and one of the most powerful broadcast towers in the country—when the engine suddenly flooded out and died. The radio waves so confused the Electrojector injection system that it began filling the engine’s oil sump with raw fuel.

“At that point we began madly shielding all the wiring associated with this system but that wasn’t enough. It really wasn’t what was needed to put the Electrojector system into ordinary passenger car service with regular customers driving around here, there, and everywhere. “This was long before the advent of what are now called Electro-Magnetic Compatibility (EMC) labs—huge rooms where the car can be driven on a chassis dynamometer while it’s bombarded with radio waves of various frequencies and intensities.

“Also, the Electrojector control unit had circuit boards filled with transistors rather than the integrated circuits in common use today. That system had only one electrical driver for all eight solenoid injectors. The signal to open was delivered to the appropriate cylinder by a rotating disc added to the ignition distributor.

“The second memorable experience I had with an experimental Electrojector system occurred in Highland Park at the entrance to Chrysler’s Engineering center. It was nearly quitting time and rush hour had begun on Oakland Avenue. A technician and I were hurrying back to the gate in a 1958 DeSoto sedan. When a break opened up in the traffic, I mashed the throttle wide open to take advantage of it. Unfortunately, the throttle linkage jammed. By the time I got the steering sorted and reached for the ignition key, we were on a collision course for a telephone pole next to the five-story engineering building’s entry door. I smashed the right-front fender there in front of God and everybody, which made me quite famous around engineering for several days.

“That particular car was equipped with long, ram-tuned intake manifold runners for improved torque. This required a system of rods running from the throttle pedal all the way to the other side of the engine compartment where the intake plenum and throttle body were located. The combination of turning and a wide-open throttle application caused the cumbersome linkage to stick in the over-center position.”

So Hoover received both barrels of bad luck while working on Chrysler’s Electrojector fuel injection: one major electronic calamity trigged by electro-magnetic interference and a second mechanical failure caused by faulty throttle linkage.

These experiences were prophetic. Customer dissatisfaction with the Electrojector system -- which cost an extra $500-637 -- began shortly after the first cars so equipped were delivered. The paper and metal foil capacitors used then were especially fragile when exposed to weather, vibration, and underhood temperature extremes. The reliability and drivability issues were so overwhelming that Chrysler soon shipped two-four-barrel-carburetor induction systems to replace the troublesome fuel injection equipment. Of the 35 sets built and sold on Chrysler 300Ds, Dodge D500s, Plymouth Furys, and DeSoto Adventurers, only one running Electrojector car still exists.

This was not the end of Bendix’s good idea. Following efforts aimed at improved reliability, Bendix licensed the technology to Bosch in 1965. Renamed Bosch D-Jetronic, it went into production for 1968 model year Volkswagen 411s and Porsche 914s. Soon thereafter, various Mercedes-Benz, Saab, Volvo, and Jaguar cars successfully used the system. Bendix finally got back in the game with its version of D-Jetronic, adopted by Cadillac for the 1977 Seville.

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