My Z has been starting like this for a while now but I've noticed that it's worse when it's cold. I took this video this morning before going to work. It was about 33 degrees in the garage when I left. Sorry that there's not much sound and the quality isn't great being that it was taken with my Iphone:

http://www.youtube.com/watch?v=8aqAAPPO3j8

 

Try cleaning the MAF?

 

I've tried that before. I was told by my tuner that it could be a vaccum leak but I can't find one. Could an exhaust leak cause it to do this?

 

Does the dash actually go completely dark just before the engine starts running? You're not doing anything with the gas pedal are you?

Taking that long to start (I'm assuming that's the engine cranking over before the dash goes dark.) makes me think fuel delivery, possibly something to do with the pump or filter.

On a cold start, the O2 sensors haven't reached operating temperature, so an exhaust leak probably wouldn't have much effect on the mixture yet.

 

When the gauges go dark is when the engine is cranking. Before they go dark is when the key is in the 'on' position. In the video im not touching the gas or anything else but the clutch. I can tap the gas to keep the RPM's up though.

 

try cleaning the MAF and do the ecu reset.

 

^I've done both

 

I have something very similiar. The interesting thing is that it seems like it has corrected itself 5 months later and have not been doing it for the last 2 months or so.

 

Does the idle stabilize after its warmed up?

 

Mine did this for the first time last night

 

What is the problem?

 

The problem is why does the rpm's move so much when it's first started like in the video.

Yes it idles fine after the rpm's level out.

 

Check your coolant levels

 

Not to be an *** but what would that do?

 

mine acted kinda like that ever since I put a pop charger and plenum spacer on it years ago. doesn't do it on cold start, only after it's warmed up, shut off and restarted.

 

Now mine done this after I installed my CAI and plenum spacer but it also does what it's doing now since I have an exhaust.

 

The car should either cold idle or warm idle, not fluctuate between the two. I also suspect a vacuum leak.

 

Have you tried to get a tune for the mods you have on there or possibly get a diagnostic or perhaps get it serviced?

 

I am not too sure thats a vacuum leak, as a leak would cause the idle to bounce all the time and not just at start up.

This maybe a long shot, but my M3 had a similar issue and it ended up being a corroded and partially broken ground strap for the motor. At startup the starter was pulling so much current and using soo many things as a ground that all kinds of stuff blinked and the engine ran very rough.

 

I suspect a voltage issue also. How are the battery terminals. Since its hidden under a cover you may never think to look.