Jamey Harris wrote:
>
> Is an Oxygen sensor a suitable replacement for an EGR valve? My EGR
> valve is apparently leaking and needs to be replaced.
A gentle no, sir.
An oxygen sensor is an entirely different contraption than an EGR valve.
The EGR valve trickles exhaust gas back into the intake manifold. The
hot exhaust gases cool the combustion process -- figure that one out.
Oxygen sensors are used to monitor the amount of oxygen in the air. It
actually measures the differential of oxygen from inside and outside the
pipe. From the leads off the sensor you will see anything from .4 to 1.4
volts. I think the .4 is lean and the 1.4 is rich and about 1 volt is
just right. There are now aftermarket gizmos on the market to have a
guage on the dash to show lean/good/rich conditions and they use the
oxygen sensor for input. Kinda cool.
All computer-controlled, fuel-inected cars use the oxygen sensor to
control the amount of fuel going into the motor. This is called "closed
loop" as the computer can get feedback from the oxygen sensor to control
the pulse width at the fuel injectors. The things don't react all that
fast, however, and at WOF, the computer uses pre-programmed calibrations
for the injectors.
On cars 1996 and newer (in the U.S.), there is an oxygen sensor on each
side of the catalytic converter as part of the government mandated "on
board" diagnostics (version 2 aka OBD-II). It has been a real pain for
the 'cat-back' exhaust system folks. It's not such a bad thing, kinda,
and you might as well like it because you're paying big dollars for it.
The computers in cars now have replaced the garage mechanic and a good
portion of the drivers brain in determining the health of the motor. Now
the garage mechanics can have much cleaner occupations as greeters at
Wal-Mart and drivers have more time for other things: using the
cell-phone, putting on their makeup, and reading the sports page,
reloading, etc.
Bob Allen, Kansas City, '69CGT, '75TR6
|