O2 sensor readings, DB

[Bob Harris <b1werks2@xxxxxxxxxx>]

Ron -

The CCC controls it all, with info from other things. In this case, the
water temp sensor. It should have a resistance of up to 950 ohms when cold,
from 1200 to not more than 1500 when the water is warm. The sensor tells the
computer when it senses warm water, the computer tells the timer that it
should start its clock running and when that is done, (70 seconds), the
system goes closed loop. The Oxygen sensor is presumed to have warmed up to
its intended rating by this time - the computer also tells the solenoid
valve (electrically), that controls the Vapor Collection Cannister to open
its' purge valve, the water temp sensor for the EGR Valve simutaneously
tells the same vacuum system to begine opening the EGR Valve and the
Diverter Valve on the Air Pump diverts the air flow from the pump from the
rear of the engine heads to the downstream catalyst in the exhaust
system.The quality of Oxygen Sensor output signals is poor until it warms
up, it apparently gets at the proper temp at the same time that the water
does, so the Computer can then add that info in determining what the Control
Pump should do and the Distributer waht it must do so that it all runs nice.
Also, there is a thermostat in the side of the Air cleaner that allows the
damper door on the draft tube to open and admit cold air - but it is not
under computer control. hope this all helps. And we expect all this stuff to
do this every time we use the car and for twenty years after that.....Bob
Harris
----- Original Message -----
From: <RWestra@xxxxxxx>
To: <mailing-list@xxxxxxxxxxxxxxxx>
Sent: Thursday, January 24, 2002 2:23 PM
Subject: Re: IML: O2 sensor readings, DB


> Thanks guys for the very interesting insight into Oxygen sensors.
> I have one additional question.  What prompts the computer to
> switch from open loop to closed loop?  Does it stay in open loop
> until it receives signals from the O2 sensor or is it prompted by
> some other input that the engine is warm enough to run in closed
> loop operation?
>
> The reason for asking is that my 81 "stalling during warm up"
> problem seems to occur at about the time I would expect the
> O2 sensor to begin to operate.  Obviously this is a guess but
> stalling seems to occur sometime between 5 and 15 minutes
> after starting cold.  It seems to vary depending upon engine load.
> The heavier the load the earlier stalling begins.  I am about to
> change the O2 sensor but I am not really convinced that is my
> problem.
>
>                                         Rolland Westra
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