RPMs drop on startup

[BadMojo]

I'm trying to get a handle on diagnosing this problem.

Approximately 25% of the time I start my car (parking brake on, clutch in, car in 1st gear) my RPMs jump up to ~1000 (if car is cold) and then dip down to ~400 RPMs. If the car is already warmed up, the The car *almost* stalls, but recovers and RPMs jump back up to normal. Once warmed up, the car idles steadily at 750 RPM.

The car otherwise idles fine and always starts up right away. It doesn't seem to matter if the car is warmed up or not, and this doesn't happen everytime I start the car.

As a side note, I've noticed that my RPMs drop by ~100 if I my passive restraint belts are moving (ie. door opened) or if I enage my pop-up headlights.

Any help you can provide would be appreciated.

[trpower7]

It's totally normal. Can't quite explain it, but I wouldn't worry about it at all.

[BadMojo]

Can't quite explain it, but I wouldn't worry about it at all.

I'm not worried really...more vexed than worried.

I've got bigger problems with this car right now, so I'll probably think about this for a while. I hate not knowing why something's happening.

[bustav13t]

i think it mite be a vacuum surge leak, but the same thing happened to me and it would only happen whenever im inside a garage, home or parking complex, otherwise, it's normal.

[notmisfit]

You should worry about it imo. As it gets worse the car will die upon start up every time. It doesn't go away it just gets worth, nothing more frustrating then having your car die every time you start it up due to the idle dropping heh.

[BadMojo]

As it gets worse the car will die upon start up every time. It doesn't go away it just gets worth, nothing more frustrating then having your car die every time you start it up due to the idle dropping heh.

What makes you think it will get worse? Have you experienced something like this?

If the car stalls out on a start up, then this problem moves to the top of my list.

Anyone else have any thoughts? I'm going to take a look around for possible vacuum leaks.

[BadMojo]

Bump? Anyone have any other thoughts? I haven't had time to really take a good look at the car yet.

[bustav13t]

i had the same prob where even when i'm driving and the idle drops to a stall. but i made sure all my vacuum lines were secure but i didnt do much, and everything seemed to be fine. also check your spark plug gaps.

[BadMojo]

Based on a suggestion over at FA, I'm going to check out my IACV (idle air control valve). I'll let you know if that's the problem. I'll most likely clean my TB while I'm at it.