Throttle Opener

Warm engine to normal operating temperature. Ensure idle speed is within specification. See IDLE SPEED & MIXTURE in the ADJUSTMENTS article.
Disconnect and plug vacuum hose at throttle opener, located on side of throttle body. Start engine. Maintain engine speed at 2500 RPM. Release throttle and note engine speed. Engine speed should be within specification. See THROTTLE OPENER SPECIFICATIONS table.
If engine speed is not within specification, rotate throttle opener adjusting screw until correct engine speed is obtained. See Fig 1. Reinstall vacuum hose on throttle opener.

Fig 1: Adjusting Typical Throttle Opener

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THROTTLE OPENER SPECIFICATIONS ⁽¹⁾

Application

⁽¹⁾ RPM

Corolla

1300-1500

⁽¹⁾	Check with engine at normal operating temperature and with electric cooling fan turned off (if equipped).