bverotti

When starting the car it revsup to about 1700 rpm. After this it goes down to about 700 rpm, but it takes like 20 seconds to get there.
Cold weather, warm weather, always same. After this initial problem the car runs smoothly, no problems whatsoever.

Any ideas ?

sales@eurocharged.com

I would be willing to bet that you have an air leak in the system. Have you tried checking all of the vacuum lines for leaks? It could also be caused by a leaking intake manifold gasket or your ECU needs to be updated.

You can go to sears (or parts store) and purchase a vacuum gauge for about $20 and connect it to service port next to the throttle body (There is a black 1" hose covering the port). Wait until your car is cold or whenever it has this issue and monitor the pressure.

I had a rough idle a few months ago and I noticed that I could cause the car to rev high at first start and it would stay that way until the pressure balanced out.

Are you running high octane gas?
Does it do it when you warm start the car?

If you have a warranty, take it to MB.

rpayer

1700 seams a little high... When you start your car it is supposed to Rev up and then drop down below 1000 RPMs to warm the catalytic converters. Same reason as to why your car will hold 1st and 2nd gear a little longer when the car is cold. However, 1700 seams a little high...

ScottW911

Mine has been doing the same thing. This morning I watched the tach more carefully and noticed it took more than 20 seconds to drop to 700 rpm. Oh well, back to the dealership before warranty expires.

Oh by the way, mine started to do this after the secondary air pump campaign was done to the car. Have you had that done yet?

exit2Ek

i don't think its anything to worry about. if you had a vacuum leak it would have a really bad idle. it wouldn't hurt to send it to the dealer and flash the ecu but unless it doesn't drop back down to 700 during idle then worry about it.