[DML] hesitation from the line

["WMARKDAVIDSON" <WMARKDAVIDSON@xxxx>]

Joe
Maybe I misunderstood what you were saying about the frequency valve. Are
you saying the frequency valve will only buzz for about a second and a half
and then stop? I do not believe that the frequency can stop working. The way
that system works is that in a cold engine situation the computer sends a
fixed signal to the frequency valve. This fixed signal is about 60% which
sets the fuel air ratio more rich that normal. This is because the computer
is being told by the tempurature sensor that the engine is cold and needs a
richer mixer than normal. Also while the engine is cold the lambda sensor
can't be looked at as feedback to adjust the air fuel mixture. This is
because the lambda sensor has not gotten hot enough to be sending a good
signal to the computer. While the engine is cold the computer is not looking
at the lambda sensor for feedback because it knows that the sensor is not
going to be sending a good signal. Therefore the computer is sending a
constant signal to the frequency valve that makes the mixture rich. It never
turns the frequency valve completely off. It keeps sending that constant
signal until the engine gets warm. Then the computer starts looking at the
lambda sensor to see how much oxygen is in the exhaust gases. The computer
then adjusts the timing on the frequency valve to adjust the air fuel
mixture. The frequency can not stop buzzing. If it does you are not
adjusting the air fuel ratio. That is the only way to adjust the control
pressure other than the control pressure regulator. And that works off of
engine temp and vacumn. That is a completely different system and is not
connected to the frequency valve.
You can see if the frequency valve is working by starting the car. Go to
the engine and listen for the buzz. If you do not hear it push the full
throttle enrichment switch. You should hear a buzz then. If you do not hear
the buzz the frequency valve is defective. If you do hear a buzz when the
full throttle enrichment switch is depressed the problem might be in the
wiring bewteen the frequency valve and the computer. Run a ground wire from
pin three on the computer to the engine block and start the car. See if the
buzz is there. There a only five parts to this system: The computer, the
frequency valve, the temperature sensor, the lambda sensor and the wiring
between all of the above.
I always though that if the frequency valve was not working you would
get a more rich mixture. I believe this is called the "lemp home" mode.
But I could be wrong.

Mark