Why does my 1997 Honda Civic idle up and down?

Classic symptom of low coolant, causing the fast idle thermo valve to stay open. That causes a high idle, which the PCM then tries to control by taking injector pulse away. This is the source of the idle surging.

How do you test the idle air control valve on a Honda Civic?

With the engine off, unplug the IAC valve electrical connector. Then use a couple of jumper wires to send direct battery voltage to the valve connector. You should be able to hear the valve working. An alternative method is to check the valve windings’ resistance using an ohmmeter.

What RPM should a Honda Civic idle at?

Typically, the idle speed will be set at a value in the range of 600 to 800 RPM, but the exact value will depend on the number of engine cylinders and whether the vehicle is equipped with a manual or automatic transmission.

Why does my 2000 Honda Civic idle up and down?

Could be low coolant, air in the cooling system(bleed system), faulty temp. sensor, vacuum leaks(spray some aerosol starter fluid around base of intake/ throttle body, vacuum lines/etc.), if engine rev’s even out or change noticeably there is the leak.

What would cause my car to rev up and down?

If the engine can’t keep idling, it will keep trying to get the engine revved up to compensate. The cause of the erratic engine you’re experiencing could be a vacuum leak, sensor failure, or an EGR system malfunction.

How do I know if my Honda IAC is bad?

5 Symptoms of a Bad Idle Air Control Valve (and Replacement Cost)

1. 1) Intermittent Idle Speed.
2. 2) Check Engine Warning Light.
3. 3) Rough Idling.
4. 4) Engine Stalling.
5. 5) Load Causes Stalling.

How do I know if my idle air control valve is bad?

Here are the most common symptoms of a bad IAC valve:

1. Check engine light comes on.
2. Rough idling.
3. Stalling.
4. Weak acceleration.
5. Fluctuating idle speed.
6. Increased idle RPMs.

What is the correct RPM at idle?

between 600 and 1,000 rpm
For regular cars, idle speed is typically between 600 and 1,000 rpm, just enough to keep the engine’s ancillary systems going, but not enough to move the car forward much.

What if my car idles high?

When your car’s throttle is malfunctioning, this can cause your car to stall or idle high. Often this is a result of dirt buildup in the air intake. Other times it can be a problem with a cracked intake tube. If the IAC motor’s vacuum port is leaking, this can be another cause of high engine idling.