High idle, after driving a bit when stop idle lopes then high
It is usually caused by the air leakage in the intake manifold. Check the following:
1. Check all the vacuum hoses from around the throttle body.
2. Under the throttle body there are three rubber hoses. Two pipes are of the same size and are used for the coolant circulation through the idle air control valve and the third one is a bit thicker than the two. It is used as the air release tube for the idle air control valve, (if the valve is separate from the throttle body). If the idle air control valve is separate type, it is attached to the side of the surge tank, other wise it is fixed to under the throttle body with Philips type screws (4 mm) as a single unit.
3. To locate the intake air leaking source, take a vacant mineral water bottle, fill it with tap water, make a small hole on the cap with a bag sewing needle, invert it and spray water by pressing the bottle with little pressure and pointing it towards a suspected area. If there is any air leaking from around the intake manifold it will produce an audible suction noise. Locate the area and fix it.
4. Remove the idle air control valve, clean and free it up and install it back.
Dec 10, 2013 |
1991 Toyota Corolla