8. PCV VALVE REPLACEMENT
1) Disconnect crankcase ventilation hose from
PCV valve.
2) Remove PCV valve from intake manifold.
3) Wind sealing tape on thread of the new valve
and install it securely.
Tightenlng torque
for PCV valve
15-25 N.m
1.5-2.5 kg-m,
11 .O-18.0 lb-ft
4) Install hose and clamp it securely.
9. OXYGEN SENSOR REPLACEMENT
[Canadian specification vehicle]
When the odometer indicates 50,000 and 100,000
miles, replace oxygen sensor as follows.
CAUTION:
To avoid the danger of being burned, do
not touch the exhaust system when the
system is hot. This work should be perform-
ed when the system is cool.
1) Disconnect battery negative cable from
battery and disconnect oxygen sensor wire at
the coupler.
1. Oxygen sensor
2. Exhaust manifold
3. Coupler
2) Remove oxygen sensor from exhaust mani-
fold.
3) Install new gasket and oxygen sensor, and
tighten it to specification.
-Tightening45torque55 N-m
4.5-foroxygensensor5.5 kg-m
33.0-39.5 lb-ft
4) Connect oxygen sensor- wire at the coupler
securely and clamp its wire.
5) Connect negative cable to battery.
6) Start engine and check for gas leak.
For Canadian specification vehicle, turn on
check switch.
7) Run engine at 1,500 - 2,000 r/min for 30
sec. after warming up engine. Check to be
sure that “CHECK ENGINE” light flashes,
and turn off “CHECK ENGINE” light cancel/
check switch on steering column holder
bracket.
1. Cancel switch (U.S.A.)Check switch (Canada)
2. instrument panel
3. Steering columnholder bracket
4. Steering wheel
10. CATALYTIC CONVERTER INSPECTION
1) All accessories (wipers, heater, lights, etc.) are
out of service.
2) Warm up engine to normal operating tem-
perature.
3) Connect CO tester to mufler tail pipe.
4) With the engine warmed up, keep the engine
speed at 1,500 to 2,000 r/min. (t-pm). If the
CO concentration is 0.4% or less in this state,
the catalytic converter is in good condition.
If it exceeds the specification, refer to DIA-
GNOSIS (p. 5-15).
1-10
5-2. DIAGNOSIS
POSSIBLE CAUSES OF EMISSIONS TEST FAILURES
Excessive Emission
Hydrocarbons (HC)
ExplanationPossible Causes
Excessive hydrocarbons arel Engine not at normal operating temperature
caused by an air/fuel mixture
that is not burning completely.l Disconnected, obstructed, leaking, or misrouted
vacuum hoses
l Vacuum leaks
.
l Maladjusted idle mixture
l Improper adjusted/sticking choke
l Maladjusted initial spark timing
oDefective spark plugs, wires or distributor cap
l Malfunctioning MCV
lLead contamination of catalytic converter
l Malfunctioning feed back system
Carbon monoxide (CO)Excessive carbon monoxidel Engine not at normal operating temperature
emissions are due to a mixture
that is rich.0 Maladjusted idle mixture
l Improperly adjusted/sticking choke
l Lead contamination of catalytic converter
lLeaking carburetor fuel passages or gaskets
0 Carburetor float level
0 Restricted air cleaner element
l Malfunctioning feed back system
Oxides of nitrogen (Nox)Excessive oxides of nitrogen
are generally due to high tem-
peratures in the combustion
chamber.
l Obstructed/Ieaking/misrouted vacuum lines
0 Improper operation of the EGR system
l Plugged EGR passages
l Inoperative BVSV or TWSV
l Lead contamination of catalytic converter
l Malfunctioning feed back system
5-15
