Contents: Carburetor engines ⇊ Injection engines ⇊
Carburetor engines
On carburetor engines, the idle speed should be checked with the engine warmed up normally and the fast idle system not engaged. Connect an external tachometer or use the standard one on the instrument panel; the onboard one is at least as accurate as the external one.
Adjustments are made with the idle speed adjustment screw located on the carburetor. This is a mechanical adjustment that simply opens or closes the throttle valve slightly, thus changing the idle speed. On the Accord, the throttle lock has a knurled plastic head to make adjustments easier. The head, however, is located on the firewall side of the carburetor and can be difficult to access. A spring on the adjuster also makes it difficult to turn the lock.
The Prelude, with its dual carburetor arrangement, uses a vertically mounted screw acting on the throttle linkage. The screw is located between the two carburetors.
WARNING: Especially on the Prelude, but not the Accord either, be absolutely certain you have found the correct screw before attempting to adjust. The screws on the linkage mechanism that are sealed with paint, usually yellow, should NOT be used. These are the factory adjusters.
Injection engines
1985 Accord SEi
1. Start the engine and warm it up to normal operating temperature; the cooling fan should run at least once.
2. Connect a suitable tachometer using the manufacturer's instructions.
3. Check the idle speed with all equipment turned off.
To prevent the idle speed control system from working, remove the vacuum hose #27.
4. The idle speed should be 750±50 rpm (in neutral position). Adjust the idle speed, if necessary, by turning the idle speed adjustment screw.
5. Check the idle speed controller, which increases the speed when the air conditioner is on. The idle speed should be 800±50 rpm (in neutral position).
6. Adjust the idle speed, if necessary, by turning adjusting screw B.
1986-91 ACCORD and PRELUDE
1. Start the engine and warm it up to normal operating temperature; the cooling fan should run twice.
2. Connect the tachometer.
3. On 1986-87 Accord and 1984-87 Prelude, disconnect the upper vacuum hose to the idle air control solenoid valve (between the valve and the intake manifold) from the intake manifold. Cap the ends of the hose and the intake manifold.
4. On 1988-91 vehicles, disconnect the 2-pin EACV connector.
5. With all accessories off, check the idle speed. The idle speed should be 750±50 rpm (in neutral). Adjust the idle speed, if necessary, by turning the idle speed adjusting screw.
6. Turn the ignition key to the OFF position.
7. Reconnect the connector, then remove the CLOCK fuse in the underhood fuse box for at least 10 seconds; this will reset the ECU settings.
8. Check the idle speed with the heater fan switch in the "HI" position and the air conditioner on. The idle speed should be 750±50 rpm (in neutral). Adjust the idle speed, if necessary, by turning the adjusting bolt on the air conditioning idle speed increase valve.
9. After adjustment, connect the idle speed control solenoid valve vacuum hose.
10. On models with automatic transmission, after adjusting the idle speed, check that it remains within the specified limits when the engine is shifted into gear. The idle speed should be 750±50 rpm.
11. Check the idle speed with all accessories on and the air conditioner off. The idle speed should remain 750±50 rpm.