nsxd11101a.pdf

Fast Idle Thermo Valve
Description
To prevent erratic running when the engine is warming
up, it is necessary to raise the idle speed. The fast idle
thermo valve is controlled by a thermowax plunger.
When the engine is cold, the engine coolant surround-
ing the thermowax contracts the plunger, allowing ad-
ditional air to be bypassed into the intake manifold so
that the engine idles faster. When the engine reaches
operating temperature, the valve closes, reducing the
amount of air bypassing into the manifold.
IAC VALVE
FAST
IDLE
THERMO
VALVE
AIR BYPASS VALVE
WAX
Inspection
NOTE: The fast idle thermo valve is factory adjusted; it
should not be disassembled.
1. Start the engine.
2. Remove the cover of the fast idle thermo valve.
3. Put your finger on the valve seat area and make
sure that there is air flow with the engine cold
(engine coolant temperature below 86°F (30°C)
and idling.)
FAST IDLE THERMO VALVE
If not, replace the fast idle thermo valve and
retest.
12 N.m
(1.2 kg-m, 9 Ib-ft)
O-RINGS
Replace
4. Warm up the engine (the cooling fan comes on).
5. Check that the valve is completely closed. If not,
air suction can be felt in the valve seat area.
If any suction is felt, the valve is leaking.
Check engine coolant level and for air in the
engine coolant system. If OK, replace the fast
idle thermo valve and recheck.