Let's Take a Look at How to Properly Set Idle Up for Fuel Injection Car Air Conditioning

The idle up system in cars is useful for increasing engine RPM when electrical and engine loads rise, where Idle itself indicates the stationary condition at the engine's RPM. 

By performing idle up, it can prevent the engine from stalling due to the added load when the AC is turned on. Here’s how to set idle up for fuel-injected cars.

How to Set the Idle RPM of Fuel-Injected Cars

In fuel-injected cars that have an EFI fuel system and utilize by pass air, the idle up equipment uses a VSV equipped with a membrane or diaphragm. 

This way, air can enter through the surge tank, and the ECU can then add fuel injection from the additional air entering from the surge tank.

Idle Speed Adjusting Screw

The way to set idle up for fuel-injected cars can be done through the idle speed adjusting screw. The idle speed adjusting screw or ISAS, which is a bolt, can be turned to the right and to the left. 

If you turn it to the left or in the direction that loosens the bolt, the idle RPM of the engine will increase, because the airflow through the idle hole will also increase.

Conversely, if you turn it to the right, it can cause the idle RPM of the engine to decrease. 

This is because the idle speed adjusting screw will reduce the airflow in the idle hole, thus decreasing the volume of air and lowering the idle RPM of the car engine. 

Read also: Car AC and How It Works

In essence, turn left to increase and turn right to decrease RPM. When performing the idle up setting for fuel-injected car AC, you need to position the idle RPM of the engine to a normal position first. 

This normal position should match the standard RPM for fuel-injected cars, which typically ranges from 750 to 850 RPM. After that, try adding an additional load to the engine by turning on the AC and headlamp of the car. 

If you find the engine drop or suddenly stall, then turn the idle speed adjusting screw to the left a quarter turn. Then, try starting the car engine along with the AC and headlamp again. 

Adjust the engine RPM correctly until the engine does not stall when the headlamp and car AC are turned on. Also, always pay attention to the RPM value when setting idle up for the car AC injection.

The method of setting idle up on fuel-injected cars is the easiest and safest step, and you can use it in emergencies while on the road. 

However, not all fuel-injected cars provide an idle speed adjusting screw directly on the throttle body. If you do not find the ISAS, then the best step is to visit the nearest workshop.

Read also: Tips to Keep Your Car AC Cool