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Lean Burn
Feb 4, 2025
All about Chrysler's Lean Burn System, the much-maligned first use of computers in cars!
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0:00
hi there my name is Dave I'm from
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motels.com and I'm here to talk to you
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about lean burn the world's first engine
0:07
control was the company in charge of the
0:10
remote diagnostics for the moon rockets
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and they also installed it on their
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Abrams Tanks when they actually started
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making those and when the moon rocket
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program wound down they had a bunch of
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electronics experts in manufacturing
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with no clients and no use so we saw a
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lot of Racing Equipment suddenly digital
0:29
testing
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which brought their racing efforts
0:32
forward quite a bit we saw the world's
0:35
first standard electronic ignition
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systems we saw new alternators and we
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also saw the world's first onboard
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computers used on cars now this was
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launched on some 1976 cars and all it
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did was control spark Advance more
0:50
intelligently than the simple vacuum and
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mechanical systems and over the next few
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years they'd have a lot of problems uh
0:57
partly from materials Technologies not
1:00
being quite up to the St up to what they
1:03
needed to be you know it's hot and it
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shakes under the hood so it was a major
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step forward in vacuum advance so
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looking Year bye they first start out
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with lean bur in some premium V8 engines
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in some 1976 cars the next year they
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simplify it a bit so the 1978 lean bur
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system was then used on most of the
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Chrysler V8s and it had a single
1:25
integrated circuit board and the system
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was fairly sophisticated for the time it
1:30
measured engine speed that's revolutions
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load throttle position speed of throttle
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movement incoming air temperature
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anti-freeze temperature and the amount
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of time since the engine had started so
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timing was Advanced at higher engine
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speeds while warming up at part throttle
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and when the driver was really calling
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for power also at cooler temperatures
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and on the highway timing was slowed
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when the car was driving in the city and
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when air temperature Rose to protect
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against detonation so it was named lean
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bur by the marketers because it could be
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tuned to run engines at leaner fuel
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mixtures which saved Fuel and reduced
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emissions so the inventor was Gordon Fen
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so the first generation system was
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pretty complicated it had a completely
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different program just for starting up
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using a second reluctor pickup the
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second generation dropped the Dual
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programs and the second reluctor pickup
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so the next move forward was the 1979
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model year when they added an oxygen
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sensor and used the system to adjust the
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fuel mixture and this required a special
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carburetor called an electronic feedback
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carburetor the earliest systems all used
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analog computers and they started using
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digital computers with the 360 V8 and
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1980 cars now although leburn has a
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pretty bad rep in the Enthusiast
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community and most people think of it as
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only being the 70s the fact is that it
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was also used in the 1980s on the
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Reliant neries with their 2.2 L engine
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and those had electronic feedback
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carburetors from the start and they had
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pretty good reputations they had
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adaptive memory starting on some of the
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1982 4 cylinders and by then pretty much
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all Chrysler cars had a feedback
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carburetor system with a catalytic
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inverter even when they moved to fuel
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injection it was pretty much an
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outgrowth of the same system and so lean
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bur You could argue continued on into
3:29
modern cars
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