Fast Idle Thermovalve (engine B16A5)
Description
To prevent idling as the engine warms up, the idle speed must be increased. The fast idle thermostat valve is controlled by a thermowax plunger. When the engine is cold, the engine coolant surrounding the thermowax compresses the plunger, allowing additional air to be bypassed into the intake manifold so that the idle speed increases. When the engine reaches operating temperature, the valve closes, reducing the amount of air bypassed into the intake manifold.
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Inspection
Note: The fast idle thermostat valve is factory adjusted and should not be disassembled.
1. Remove the air inlet pipe from the throttle body.
2. Start the engine.
3. Place your finger over the lower inlet of the throttle body and check that there is air flow when the engine is cold (engine coolant temperature below 30°C).
If not, replace the thermostat valve and check again.
4. Start the engine. Run the engine at 3000 rpm without load (in the [N] or [P] position) until the radiator fan comes on, then let it idle.
5. Check that the valve is completely closed. If the valve is leaking air, the idle speed will drop when you close the lower inlet. Check the engine coolant level and the presence of air in the engine cooling system. If OK, replace the thermostat valve and check again.
Setting the idle speed
Inspection/Adjustment
Engines D15Z6 (M/T), D15Z7 (M/T), D16Y5 (M/T), D16Y6 (M/T) D16Y8 (M/T), V16A2, V16A4, V16A5, V16A6:
Note: Before setting the idle speed, check the following:
- MIL did not come on.
- Ignition timing.
- Spark plugs.
- Air filter.
- PCV system.
1. Connect the tachometer.
2. Start the engine. Leave it at 3000 rpm without load (A/T in position N or P, M/T in neutral) until the radiator fan comes on, then let it idle.
3. Disconnect the 2K connector from the idle air control (IAC) valve.
4. Start the engine with the accelerator pedal lightly depressed. Fix the engine speed at 1000 rpm, then slowly release the pedal while the engine is idling.
5. Check idle speed under no-load conditions: headlights, fan, rear window defogger, radiator fan and air conditioner do not work
Note (KS model): Remove fuse No.18 (7.5A) in the under-panel fuse box and relay, then check that the headlights and lights do not light.
Idle speed should be:
If necessary, adjust the idle speed by turning the adjusting screw.
Note: After adjusting the idle speed at this point, check the ignition timing. If not within specification, proceed to step 4.
6. Turn off the ignition.
7. Connect the 2K connector to the idling control valve, then remove the auxiliary (RADIO) fuse (7.5 A) in the engine compartment of the fuses and relays for 10 seconds to reset the memory of the electronic engine control unit/AUTOMATIC transmission (ECM/RSM).
8. Start the engine again and let it idle without load for one minute, then check the idle speed.
Note (KS model): Remove fuse #18 (7.5A) in the under-panel fuse/relay box, then check that the headlights and lights go out.
Idle speed should be:
- Engine D15Z7: M/T: 650 ±50 rpm
- Engine D16Y8 (model KN) M/T: 670 ±50 rpm
D15Z6 engines (except for the K5 model), B16A4, B16A5
Engines D15Z6 (model KS), D16Y5, D16Y6, D16Y8 (except for the KN model), B16A2, B16A6
9. Let the engine idle for 1 minute with the headlights ON (low beam) and check the idle speed.
Idle speed should be (all engines):
10. Turn off the headlights. Let the engine idle for one minute with the heater fan switch on Hi and the air conditioner on ON, then check the idle speed. The idle speed should be:
Except for the B16A5 engine:
- Engine B16A5: A/T: 830 + 50 rpm in position [N] or [P]
Engines D15Z6 (A/T), D1527 (CVT), D16Y5 (CVT), D16Y6 (A/T), D16Y7, D16V8 (A/T):
Adjust idle speed using Honda PRM-TESTER.
If not adjusted, check the following:
Note: Before setting the idle speed, check the following:
- MIL did not light up
- Ignition timing
- Spark plugs
- Air filter
- Crankcase ventilation system
1. Connect the tachometer.
2. Start the engine. Leave it at 3000 rpm without load (A/T in position N or P, M/T in neutral) until the radiator fan comes on, then let it idle.
3. Check the idle speed under no-load conditions: headlights, fan, rear window defogger, radiator fan and air conditioner do not operate.
- Engine D16Y7 (KN model M/T) — 670 ±50 rpm
Engines D15Z6 (A/T), D15Z7(CVT)b D16Y5(CVT), D16Y6 (A/T), D16Y7, D16Y8 (A/T):
A/T: 700 ±50 rpm in [N] or [P] position
Engines D16Y5 (model KQ), D16Y6, D16Y7 (models KK, KM):
4. Adjust the idle speed if necessary by turning the adjusting screw 1/2 turn clockwise and counterclockwise.
Note: When removing the air cleaner housing, do not disconnect the intake air temperature sensor connector.
5. After tightening the idle adjustment screw by ½ turn, check the idle speed again.
Note: Do not turn the idle speed adjustment screw more than ⅓ without checking the idle speed.
6. Let the engine idle for 1 minute with the heater fan switch on Hi and the air conditioner on, then check the idle speed.
Idle speed should be (all engines):
Note: Do not tighten the idle speed adjustment screw while the fan is running.
[The text was taken from the website HONDABOOK.ru]