Honda Civic 1992-1995 EG Idle Speed and Mixture
06-23-2009, 05:44 PM
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Honda Civic 1992-1995 EG Idle Speed and Mixture
To see the original article with images check it out here: Honda Civic Idle Speed and Mixture. Garage411.com
Idle Air Control (IAC) Valve
Engine idle speed is controlled by IAC and fast idle valve. IAC varies amount of air by-passing throttle plate (into intake manifold) in response to signals from ECM. After engine starts, IAC opens for a short time to increase idle speed. Activation time is dependent upon engine coolant temperature. When coolant temperature is low, IAC is held open to obtain proper fast idle speed. After engine reaches normal operating temperature, IAC is activated only to maintain minimum idle speed.
Idle Air Control (IAC) Thermal Valve
Formerly called fast idle valve, IAC thermal valve allows additional air to by-pass throttle plate into intake manifold. Increased idle speed prevents engine from running erratically during warm-up. Valve is controlled by a thermowax plunger, which contracts when cold and expands when hot.
Idle Mixture
Idle mixture is computer controlled and is not adjustable. Maximum CO level is .1%.
Idle Speed
1. Start and run engine under no-load condition at about 3000 RPM until cooling fan comes on. Let engine slow to idle. Turn engine off. Connect a tachometer. Disconnect 2-wire Idle Air Control (IAC) valve connector.
2. Start and run engine at about 1000 RPM until engine speed stabilizes. Slowly release pedal until engine idles. Check idle speed under no-load conditions. Ensure all accessories, cooling fan and lights are off. If necessary, adjust idle speed by turning idle adjusting screw.
3. Turn ignition off. Reconnect 2-wire IAC connector. Remove BACK-UP fuse from underhood relay box for 10 seconds to reset ECM. Restart engine. Check idle speed (after ECM reset) with all accessories off and transmission in Neutral or Park. Idle speed should be stable and within specification. Turn engine off.
4. Start engine and idle engine for one minute with various accessories on. Check idle speed. Idle speed should be stable and within specification. If idle is not within specification, check vacuum hose connections. Check idle adjuster screw, fast idle valve and Idle Air Control (IAC) valve for proper operation.
5. If idle components are okay, check MAP sensor, Electronic Load Detector (ELD), fuel injector circuit, A/C signal circuit, EGR system and lock-up control solenoid (if equipped) for proper operation. On Civic VX there has been a revision as per TSB Number HSN-0894-02 dated August 1994. Idle engine for one minute with headlights (low) ON, and check idle speed.
To see the original article with images check it out here: Honda Civic Idle Speed and Mixture. Garage411.com
Idle Air Control (IAC) Valve
Engine idle speed is controlled by IAC and fast idle valve. IAC varies amount of air by-passing throttle plate (into intake manifold) in response to signals from ECM. After engine starts, IAC opens for a short time to increase idle speed. Activation time is dependent upon engine coolant temperature. When coolant temperature is low, IAC is held open to obtain proper fast idle speed. After engine reaches normal operating temperature, IAC is activated only to maintain minimum idle speed.
Idle Air Control (IAC) Thermal Valve
Formerly called fast idle valve, IAC thermal valve allows additional air to by-pass throttle plate into intake manifold. Increased idle speed prevents engine from running erratically during warm-up. Valve is controlled by a thermowax plunger, which contracts when cold and expands when hot.
Idle Mixture
Idle mixture is computer controlled and is not adjustable. Maximum CO level is .1%.
Idle Speed
1. Start and run engine under no-load condition at about 3000 RPM until cooling fan comes on. Let engine slow to idle. Turn engine off. Connect a tachometer. Disconnect 2-wire Idle Air Control (IAC) valve connector.
2. Start and run engine at about 1000 RPM until engine speed stabilizes. Slowly release pedal until engine idles. Check idle speed under no-load conditions. Ensure all accessories, cooling fan and lights are off. If necessary, adjust idle speed by turning idle adjusting screw.
3. Turn ignition off. Reconnect 2-wire IAC connector. Remove BACK-UP fuse from underhood relay box for 10 seconds to reset ECM. Restart engine. Check idle speed (after ECM reset) with all accessories off and transmission in Neutral or Park. Idle speed should be stable and within specification. Turn engine off.
4. Start engine and idle engine for one minute with various accessories on. Check idle speed. Idle speed should be stable and within specification. If idle is not within specification, check vacuum hose connections. Check idle adjuster screw, fast idle valve and Idle Air Control (IAC) valve for proper operation.
5. If idle components are okay, check MAP sensor, Electronic Load Detector (ELD), fuel injector circuit, A/C signal circuit, EGR system and lock-up control solenoid (if equipped) for proper operation. On Civic VX there has been a revision as per TSB Number HSN-0894-02 dated August 1994. Idle engine for one minute with headlights (low) ON, and check idle speed.
To see the original article with images check it out here: Honda Civic Idle Speed and Mixture. Garage411.com
Last edited by Master23; 07-01-2009 at 05:06 PM.
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