Health check
1. Verify that the engine warmed up to operating temperature gives, with all accessories disconnected, 800 rpm for manual transmission models and 750 rpm for automatic. If the speed does not match the specified one, then you should not rush to adjust it.
2. Remove the vacuum hose from the top of the idle speed boost control and attach a vacuum gauge. There shouldn't be a vacuum. Turn on the air conditioner - a vacuum should appear. When connecting the hose back to the regulator, the idle speed should return to the set one.
3. If there is a vacuum in the boost regulator when the air conditioner is off, then the solenoid valve connector should be disconnected (supplying vacuum to the regulator), located on a heat-insulating partition. If there is a vacuum in this case, then the solenoid valve is faulty.
4. If there is no vacuum when the air conditioner is on, then check the voltage at the solenoid valve. It should be 12 volts. If the voltage is normal, then the solenoid valve is faulty. If there is no voltage (on the red wire), then you need to check the voltage (12 volt) on terminal A8 of the ECU with the air conditioner on. If there is voltage there, then the wiring is faulty. If there is no voltage, and the air conditioner works properly, then the ECU device is faulty.
Regulation
1. If the idle speed controller is working properly, then start the engine to idle and disconnect the vacuum hose from the solenoid valve. Attach a hand pump to the regulator.
2. Pump out the air. The idle speed should increase to 1200 rpm. Remove the cover from the adjusting screw located on top of the regulator and, by rotating it, set the desired idle speed.