Idle Control Valve
Without an efficient idle control valve, there's nothing to maintain the right engine idle speed. When you stop at a red light or while you're parked, engine RPM won't be steady. The engine might idle roughly or stall.
Through this valve inside the throttle body, just the right amount of air is able to get through the throttle plate. Through signals from the ECM, or electronic control module, the pintle can shift its position on the valve opening to decrease or increase the engine RPM as needed. Unfortunately, this air control valve may wear out or go bad once carbon has built up or when it gets stuck.
Common symptoms of an idle control valve gone bad
- Lower RPMs when idling. When the air control valve is malfunctioning, this may lead to a restricted airflow to the engine. Inadequate amounts of air that get through the engine can lead to lower engine revolutions per minute when idling.
- Engine may stall when idling. A plugged valve can cause the vehicle to stall as the engine RPM steadily drops. The vehicle may run fine when you press on the gas, but when it slows down, the engine may sputter and stall.
- Engine idles roughly. A busted valve may fail to regulate engine speed through the airflow. When stuck open, the faulty valve can cause rough idling. In this case, vibrations and shuddering might be felt even when the car isn't in motion. When the engine idles roughly, starting the vehicle can be rough as well. The cranked up engine may eventually stall.
- Engine starts properly when cold but stalls after ignition when warm outside. Starting the engine can be a bit of a trouble when the air control valve is messed up. There'll be some irregularities. For instance, starting the engine when it's cold is easy, but when you press on the accelerator, the car may stall. When it's warm outside, the opposite may happen. The engine can be cranked up easily, but this may eventually stall right after ignition. You have to step on the accelerator right away to prevent stalling.
Aside from stalling, rough idling, lower RPMs, and troubles starting the engine, also take note of these tell-tale signs of a bad idle air control valve: unusual racing noise that can be heard from the engine, the engine suddenly shutting off when air-conditioning is switched on, and the Check Engine Light coming on to tell you that something's wrong.
Tips for fixing a bad idle control valve
- Have the car's computer system scanned to check for codes, so you'll know what's wrong with the engine.
- Do something when the Check Engine Light comes on.clear it right away.
- Look for any vacuum leaks, as these can have the same symptoms as a faulty valve.
- Inspect electrical connections to find out what's really causing the engine problems or its poor performance.
- Remove carbon deposits on intake manifold ports to keep the valve from messing up.
- Replace a malfunctioning air control valve as soon as possible to prevent troubles like rough idling and stalling.
To keep the idle control valve from getting stuck or broken, make sure that air induction service is done every 3 or 4 years. This routine maintenance will keep carbon from building up on the valve.