High Idle RPM when Cold - '86 300E
 

When the external temperature is in the 60's or below, and I start my car after it has been sitting overnight, the engine idles at about 1400 rpm and it takes about 3-5 minutes for it to come down to normal idle rpm. In this time, the coolant temperature reaches 50-55 degrees.

The car is an '86 300E with 72K miles on it.

What could be a possible cause for this or is this normal?

Thanks in advance.

hs

I'm 99% sure this is normal. Mine does this as well irregardless of outside temperature. Generally the the first minute the car runs at about 1100RPM until the temperature starts climbing. It then settles down to 600RPM. The cars have a cold start operation which does this.

i think over 1000rpm is a bit high. mine rev to 900
in about 2 mins before settling down to normal idle (700rpm).