How to adjust the engine speed of EFI automobile?

If you mean speed, just step on the gas pedal. If you mean idling, most cars can't be adjusted now. They are all set by the factory, and a few cars can be tuned by special computers.

1, increase the idle speed: just adjust the throttle opening (increase the intake air). Lift the limit screw at the throttle cable to make the throttle have a certain intake angle, and the idle speed naturally rises.

2. Reduce idle speed: Since the original throttle is basically closed, it is difficult to adjust the throttle, but it is not impossible to adjust it.

3. The simplest way is to add a gasket with proper size at the joint between the idle valve and the throttle body, so as to reduce the air flow from the idle valve to the engine by physical means. When the air flow decreases, the idle speed will naturally decrease.