Fast Idle Thermo Valve (Aft) - Honda CR-V 1997 Service Manual

Idle Control System
Fast Idle Thermo Valve (AfT)
Description
To prevent erratic running when the engine is warming
up,
it
is necessary to raise the idle speed. Th e fast idle
thermo valve is controlled by a thermowa x plunger.
When the engine is cold, the engine coolant surrou nd-
ing the thermowax contracts the plunger, allowing addi-
tional air to be bypassed into the intake manifold so that
the engine idles faster. When the engine reaches operat-
ing temperature, the valve closes, reducing the amount
of air bypassing into the intake manifold.
IDLE
SCREW
AIR BYPASS VALVE
11-168
FAST
IDLE
THERMO
VALVE
Inspection
NOTE: The fast idle thermo valve is fa ctory adjusted; it
should not be disassembled .
1. Remove the intake air duct from the throttle body.
2. Start the engine.
3. Put your finger over the lower port in throttle body,
and make sure that there is air flow with the engine
cold (engine coolant temperature below 86"F, 30"C).
LOWER
PORT
If there is no air flow, replace the fast idle thermo
valve and retest.
D.ftINGS
Replace.
""':s::::--_._ ...
9.8N·m
(1 .0 kgl·m. 7.2 Ibf.lt)
4. Start the engine. Hold the engine at 3,000 rpm with no
load (in Park or neutral) until the radiator fan comes
on, then let it idle.
5. Check that the valve is completely closed. If the valve
is leaking, the idle speed will drop when you cover the
lower port. Check the engine coolant level and for air
in the engine cooling system (see section 10). If the
cooling system is OK, replace the fast idle thermo
valve and recheck.