Chevrolet Impala SS, Handbook

Page: 73 / 159

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SSHandbook
Maintenance: General Maintenance
Oxygen Sensor Replacement
Oxygen Sensor replacement is recommended around every 100,000 miles. Although it is okay to change
them whenever you want and they may go bad anyway. They will cause bad gas mileage, sluggish
performance and build up due to reading the wrong fuel/air mixture. You cannot “rejuvenate” an O2 sensor or
“clean” it. They will usually go bad during a season change.
For 1995 and before:
You have two O2 sensors, both in front of your catalytic converters. You will need an O2 socket or a
wrench to remove them. It is good to replace them while the exhaust is still a little warm and spray them with
a loosening agent i.e. PB Blaster, WD40. Sometimes they’re easy, sometimes they’re not.
For 1996:
Since a government mandate to help with emissions, the 1996 B-bodies along with all other automobiles
will have O2 sensors after the catalytic converters.
You will have four O2 sensors since you are OBD II. Two are behind your catalytic converters and are
useless except for emissions testing. If you do not have emissions testing in your state you can replace those
with simulators. The other two are in front of your cats and, along with the PCM and a few other sensors
control the entire fuel/air cycle of your car. You cannot replace those with anything other than real O2 sensors
unless you want the car to run like crap. If you convert to OBD I you can leave out the rear O2 sensors
entirely, not even simulators needed. Note: if you live in a state with emissions testing you will still have
problems, as many states are moving to plugging into your PCM for 96 and newer cars and you'll fail if you
have the OBD I conversion.
PCV Valve Replacement
PCV Valve
The PCV valve, or Positive Crankcase Ventilation
valve, is located on the driver’s side of the throttle body
between the #3 and #5 fuel injectors (the ones in the
middle). Many people tend to forget about this small
valve, and it’s recommended to change it every 12
months to 12, 000 miles.
The PCV Valve and Breather Element work together
within the car’s emissions and ventilation systems. They
serve as part of the emissions control system by re-
circulating unburned gases and fumes back through the
intake manifold to be re-burned. Therefore, these gases
and vapors are not expelled through the exhaust system
so air pollution is reduced.
Benefits ofchanging the PCV Valve:
• Loss of power, oil dilution and even engine failure are avoided
• Oil life is extended and engine lubrication is improved
• Oil consumption, rough idle and air filter contamination are avoided
• Environmental pollution is reduced