[DML] air fuel settings

["WMARKDAVIDSON" <WMARKDAVIDSON@xxxx>]

Duke
If you have a dwell meter ($35.00) you can get the air fuel (AF) ratio
pretty close.
1. Find the diagnostic plug. On the left rear fire wall. Attach the ground
from the well meter to pin # 2 on the plug. Attach the other wire from the
dwell meter to pin # 3 on the diagnostic plug. Set the meter on Dwell.

2. Crank the engine. Let it get warm. This is so that the oxygen sensor is
sending a good signal to the Lambda Control unit.
When the engine is cold the computer sends a fixed signal to the frequency
valve. You can see this fixed signal on the dwell meter. The read out on the
dwell meter will be 60% duty cycle or about 54 on the four cylinder scale.
When the engine gets hot the computer starts looking at the oxygen sensor
and adjusting the frequency valve to adjust the exhanst level. If the dwell
meter needle swings high (60% to 70% or 54 to 63 on the four cylinder
scale)on the scale when the engine is warm the mixture is set to lean. Turn
the AF screw on the distrubter clockwise just a little. Remove the allen
wrench from the AF screw and let the system settle and look at the dwell
meter reading. If the needle swings low (29% to 37% or 26 to 33 on the four
cylinder scale)the mixture is set too rich , turn the screw counterclockwise
to lean the mixture.
This is explained much better in the book "Bosch Fuel Injection & Engine
Management" by Charles O. Probst. Look on pages 32 and 33 for a better
explanation.

Thanks
mark