A 2004 Volvo S60's idle dropping to 500 RPM when stopped could be caused by several issues, such as a vacuum leak, a malfunctioning idle air control valve, or dirty throttle body. It could also indicate problems with the fuel system or engine management sensors. Checking for any diagnostic trouble codes (DTCs) can help pinpoint the issue. Regular maintenance and cleaning can often resolve these idle fluctuations.
640 rpms
You have a vacum leak. A big one. Check all your hoses. Idle should be under 1k rpms
your alternater is most likely shot. if you replace it and the battery you should be good as new.
Most cars are anywhere between 750-800 rpms
of Idle
It should idle at aprox 650 rpms warmed up.
If you have an engine that idles at 6000 rpms, you need to have it checked - immediately. Around 750 rpms would be normal.
800 rpms.
5 to 6 hundred rpms. Is recommended idle
an idle rpm for a 350 stadard trans. is about 500 rpms. an auto is about 750 rpms. this is if the eng. has a stock cam. if not it may vary
Because of the loss of backpressure if can affect the idle.
cars idol speed in 640 rpms