Why does the Honda 2.4 CR-V have high idle speed when cold?

[OGideon]

Honda 2.4 CR-V high idle speed when cold may be caused by issues such as an unclosed idle switch or a faulty idle control valve. Unclosed Idle Switch: The engine speed signal determines the fuel injection quantity and injection timing. However, when the engine is operating under idle conditions, the reduced air intake leads to an overly rich air-fuel mixture, causing the engine speed to rise. Faulty Idle Control Valve: When the idle speed exceeds the set value, the ECU commands the idle control valve to reduce the intake bypass passage, thereby decreasing the air intake and lowering the engine speed. Issues such as sticking due to oil contamination or carbon buildup, or incomplete throttle valve closure, can prevent the ECU from properly adjusting the engine idle speed, resulting in unstable idle. Intake Pipe Leakage: The opening of the idle control valve and the air intake strictly follow a certain functional relationship, where an increase in the idle control valve opening corresponds to an increase in air intake. Intake pipe leakage disrupts this relationship, causing the air flow sensor to fail in measuring the actual air intake accurately. As a result, the ECU cannot control the air intake precisely, leading to unstable engine idle.

[AlexanderAnn]

I also drive an older CRV with the 2.4L engine, and it has high idle speed when cold. It's most likely due to a dirty throttle body with excessive carbon buildup blocking it. When parked, the ECU needs to control the air intake, but if the throttle body is stuck with sludge and doesn't open and close smoothly, the ECU thinks there's insufficient air intake and compensates by injecting more fuel to raise the RPM. In winter, when temperatures drop and the engine oil thickens, the ECU will also inject a bit more fuel to warm up the engine, which is normal. But if your cold engine roars with RPMs over 2000 and doesn't settle down even after warming up, it's probably an issue with the idle control valve or a sensor. Last year, I disassembled and cleaned the throttle body myself—scraped off half a spoonful of black sludge—and the idle stabilized immediately after cleaning. If you're handy, you can give it a try.

[OCamille]

High idle speed when cold is quite common on the CRV, as the engine management system needs to warm up quickly. However, if it lasts too long, several areas need to be checked: first, verify the accuracy of the coolant temperature sensor—if it falsely reports the temperature, the ECU will keep giving cold engine commands; then check for carbon buildup, especially deposits on the intake manifold and the back of the valves, which directly affect intake efficiency; an air leak in the intake system is also critical, as aging seals can let extra air sneak into the cylinders, forcing the ECU to compensate with more fuel; also, keep an eye out for the engine warning light—I once encountered this symptom due to a drifting idle valve position sensor signal.

[DelHolden]

The i-VTEC cold start logic of Honda is designed to run at high RPM for warm-up, but it should drop within two minutes. If it exceeds, focus on inspecting the intake pressure sensor and idle control valve. A dirty sensor causes unstable readings, while a stuck idle valve fails to seal properly. Last time, a colleague's CRV had its idle valve jammed by sludge, causing cold start RPM to soar to 1800—it took half an hour of carb cleaner soaking to fix. Remember to also check if the air filter box clips are broken or leaking.