Re: [DML] K-jetronic not connected

["checksix3" <jetjock11@xxxxxxxxxxx>]

Lauren,  
 
Lambda is a mathematical term used to express equalibrium. The term's 
use in automotive technology was pioneered by Bosch, the inventor of 
the O2 sensor. Bosch used the principle of the Nernst Cell, a device 
developed in 1899 that measures the partial pressure of oxygen by 
conduction of Oxygen ions through a heated ceramic electrode. They 
called it a Lambda sensor because the Greek letter lambda is now used 
to represent engine air/fuel ratio, with the perfect ratio expressed 
as Lambda = 1.

Without gettting too technical, the standard Lambda (or oxygen) 
sensor measures the oxygen content of your exhaust stream and 
compares it to the outside air. Because the partial pressure of 
oxygen in the air remains constant it's able to generate a sudden 
jump in output voltage around the "best" mixture at the point when 
all the fuel is burned and no remaining oxygen is left. Few molecules 
of either are left out of the combustion dance at this point. By 
continuosly sampling this variable and using it in a feedback loop to 
alter the amount of fuel injected the Lambda system keeps the 
air/fuel mixture at a point very close for minimal emissions. (Note 
this is *not* the optimum mixture point for best performance). 

The Lambda system exists mainly for one purpose: To pre-condition the 
exhaust stream for your catalytic converter. Since cats only operate 
in a narrow band this is required. The cat further reduces emissions 
of HC, Nox, and CO. (You can tell if your cat is working simply by 
measuring the temperature delta across it's inlet and outlet).

The O2 sensor on the Delorean is primitive by today's standards. This 
standard sensor doesn't come "alive" until it reaches about 600 
degrees. Until that happens the car is designed to run open loop and 
slightly rich. From an emission stanpoitn cars are "dirtiest" when 
cold and the sooner the O2 sensor operates the sooner we can get the 
emissions under control.

To get around this problem the electrically heated O2 sensor was 
developed. These days most O2 sensors are of the Planar Thin Film 
type in addition to being heated. They allow closed loop control in 
as little as 15 seconds after a cold start. Some newer vehicles are 
designed to run lean and a newer "wide band" sensor using different 
technology is employed in those cars. They're able to continuosly 
monitor O2 levels over a wide range.  

Modern cars with OBDII (On Board Diagnostic Generation 2) use an 
additional O2 sensor downstream of the converter to further monitor 
emission performance.

It's not difficult to retrofit your D to use a heated or even a 
planar heated sensor. No matter what you use it's a good idea to tap 
the line with an A/F meter so you can watch the system in operation. 
Other that EGT there is almost no other method that will tell you 
more about how your engine is running than monitoring the O2 sensor. 
If it's jumping around midpoint (called cross counting) it tells you 
the syetm is working correctly. (Not only the sensor but all the 
associated components of the Lambda system or EFI, if so equipped). 
These devices are also invaluable for tuning a fuel system after 
modification.

There is more to it of course but I hope this answers your question.


--- In dmcnews@xxxxxxxxxxxxxxx, "Lauren" <LPLand@xxxx> wrote:
> 
> > That's the lambda computer
> 
> Just my eternal curiousity -- why is it called "lambda?"
> 
> .........................LP
> owner, potential driver of 10440




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