QuestionQUESTION: My 1991 GTS toyota celica has a fast idle (1800 rpm) even when the engine is warm. I have already turned the idle adjust screw all the way down.
ANSWER: Check to make sure the throttle cables are not binding and keeping the throttle plate from closing all the way, check the vacuum hose that goes to the diaphragm on the throttle body, make sure the hose is attached, if the hose is not on it will keep the throttle open a little just enough to cause this problem.
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QUESTION: Thank you for your answer. I checked the throttle cable and all the vacuum hoses and they are all fine. The throttle plate is definitely closed all the way but I still have the high idle, although it does go down to 1000 rpm when the air conditioner is turned on. Help!!
AnswerThis engine has an idle speed control valve located on the bottom of the throttle body, it may be sticking due to exessive carbon deposits, the throttle body has to be removed to get the valve off, in most cases the valve can be cleaned and made serviceable, check the moving part of the valve inside after cleaning it to make sure it's not sticking, use a small screwdriver to move the valve, it should return to almost close by itself, clean it using air intake spray cleaner and a nylon brush.
