1991 Acura Integra idle

Too fast an idle speed. If an engine without computerized idle speed control is idling too fast and refuses to come down to a normal idle speed despite your best efforts to back off the carburetor idle speed screw or air bypass adjustment screw (fuel injection), air is getting past the throttle somewhere. Common leak paths include the carburetor and throttle body gaskets, carburetor insulator spacers, intake manifold gaskets, and of course, any of the engine's vacuum fittings, hoses and accessories. It is even possible that leaky O-rings around the fuel injectors are allowing air to leak past the seals. Another overlooked item can be a worn throttle shaft and a defective idle speed speed control motor/valve stuck in the extended (high idle speed) position/throttle position sensor. Also the throttle plate could be binding in its bore and kinked accelerator cable, coolant temperature sensor might not be operating properly misleading the computer that the engine is still cold and computer throwing fuel at it raising the idle speed.

Hi fruitcat79,

My fellow technician is offline and I will be assisting. He posted an excerp and it mentioned either carb or injection to cover both.

For your model the IAC can cause the problem of high idle but quite often it is the fast idle valve that is the culprit. However high idling speed would not cause the AC to blow hot air. In fact a higher idling speed should have the AC working colder. This should be a separate problem.

The fast idle valve is located under the throttle body. Remove air intake hose and at bottom of throttle body you would notice an air passage, if covering it with your finger reduces the idling speed, the valve has worked itself loose due to a hardened O ring.

If it does not reduce the idling speed, cover the upper air passage, if it reduces the idling speed, the IAC is afulty.

If both does not reduces the idling speed, you have a vacumn leakage after the throttle plate, could be brake booster, PCV or inlet manifold gasket.