Quick Answer: Why Is My Car Rpm Not Stable?

Why does my RPM go up and down while AC is on?

When the additional load of your AC compressor is added, it causes the computer to miscalculate and increase idle speed too much.

Bad Belt: One often overlooked cause of a car surging with the AC on is actually a worn compressor belt.

If the belt is stretched or worn smooth, it can slip during operation..

Why does my car RPM go up and down when in park?

If your car has an idle air control valve, that could be going out, if you have an electronic theottle body, that could be dirty. … After a few minutes or so, the engine will stabilize and calibrates by itself, it could speed up or slower down the rpm of the engine when the car is on PARK.

What causes RPM to fluctuate when driving?

For the engine surging making the rpm’s go up and down could be caused by a defective or stuck idle air control valve (IAC). Check the IAC and see if it’s working. Remove the vacuum line to the valve and see if the engine runs smooth. If the engine runs smooth, then the IAC needs to be replaced.

What should your rpm be while stopped?

The idle speed should feel consistent without skipping or slipping. In most of today’s cars, an idle speed of 600 to 1000 RPMs is average. If your car is idling rough, though, it won’t feel smooth. The RPMs will jump up and down, for example, or they’ll fall below 600 RPM (or whatever is typical for your vehicle).

What can causes a rough idle at low rpm?

Bad spark plugs, bad spark plug wires and a bad distributor cap are other common causes of rough idling. These items are all important parts of what keeps a vehicle running. … A distributor cap regulates the firing order of your vehicle’s engine. These are just a few items that could cause a rough idle.