What are the reasons for high idle speed in a hot Santana?
2 Answers
Santana's high idle speed when hot may be caused by the idle switch not closing or the idle contact disconnecting. The solutions are as follows: 1. Check the throttle opening. If the basic idle speed is too high, inspect the vacuum sealing of the system, especially the sealing of the vacuum tube, PCV valve, and related parts of the crankcase. 2. Check the engine load signal. If the idle control valve opening is too large, verify whether the engine load signals are normal, such as the air conditioning signal, battery voltage, and the temperature value of the coolant temperature sensor. 3. Check the intake manifold vacuum. Under normal engine idle conditions, the intake manifold vacuum should be 57-71 kPa. If the vacuum is too low, it will cause abnormal pressure signals in the engine intake system, leading the engine computer to mistakenly assume an increased load and consequently raise the idle speed.
My Santana has high idle speed when the engine is warm, which is commonly caused by excessive carbon buildup in the throttle body or an air intake system leak. I've repaired several similar models before - carbon deposits blocking the airflow can cause the ECU to automatically increase RPM to maintain stability when it fails to detect proper airflow. A stuck idle control valve is also a common issue, especially in older models where valve contamination can cause it to jam, preventing RPM from dropping. Don't overlook sensors either - aging components like intake air temperature or throttle position sensors providing inaccurate data can mislead the ECU. Other causes like vacuum leaks or faulty coolant temperature sensors can also cause idle speed to surge. If you don't drive often or maintain the vehicle properly, dust accumulation becomes likely. I recommend regular throttle body cleaning - you can do it yourself with carburetor cleaner, it doesn't take much time. Otherwise, have a reputable shop inspect it. Don't delay repairs, as this wastes fuel and damages the engine.
