Rough on 1st start...still after hours of searching forums!

Here's the background...I'm a used car dealer that specializing in Europeans... I take pride in what I sell and have a 02 325Xit with 128k that's giving me a bit of issue. I know I'm a newbie here but I promise I've read every thread on the subject. So here goes nothing....

Symptoms:

1st start of the day...starts right up, idles at about 700ish or so (ambeint temps are about 30-45 these days) but feels like theres a soft miss like one cylinder is misfiring. Here's the catch...after about 40 seconds it's completely gone and will not return throughout the course of driving it during the day.

I've put about 400 miles on it, highway speeds and all and it drives mint! I just know this is not right because I have two other e46's on the lot and they don't do it

There's no active ses light. I've got a computer for BMW's and it has stored misfires 2, 4 and 6.

I originally brought it to my mechanic who's ususally decent with Euro's and they replaced one coil pack. It continued to do the same thing so I brought it to the BMW indie in town and he smoked it, checked fuel pressure, checked for leaking injectors, and looked at all the usual culprits such as intake boots, ccv system, vanos, and all the hoses and connectors, disa, etc.

I don't know where to go from here.

I changed plugs to Bosch+4, all 6 coils, and the valve cover gasket yesterday and there's no difference.


HELP!!!!!

ALSO, swapped the MAF with a known good working one...

Anybody?

Hi and welcome! For that mileage I would change fuel filter first and pour bottle of injector cleaner into gas tank during next fill up for the beginning.
Also fresh battery may help. Overnight it gets discharged causing rough idle after start, and next thing you may not start the car some day. I had this, you may search "car not start". What you have is may be early symthom or dying battery. You may find perfect aftermarket for half price vs. original BMW. Works just fine.

It's got a new battery as of a month ago. Fuel injector cleaner was used by my BMW indie. I don't see how a fuel filter would only affect the first 40 seconds after starting it cold. It has full power and doesn't miss a beat any other time.

Anyone elses thoughts on a fuel filter causing this?

Injector clener may washout from old filter dirt and clogh injectors. That's why mechanics recommend do not use injector cleaner with very old fuel filter... However your case may be really more complicated...
40 seconds... fuel pump needs develop pressure, it's more difficult with clogged filter I guess.

also may be water (condensation) in the fuel tank...

wouldn't fuel pressure loss be ruled out when they checked fuel pressure overnight with a guage and it didn't drop?

I've gone through a couple tanks of fuel too...

Did you have oil change lately?

Mine was bit rough in starts but fresh oil seem to helped about it.
As if some parts get enough lubrication only after engine warmed up?

Ofcourse yours might have some other reason as well...

Yeah I actually changed it a few hundred miles ago to MObil 0w40

Thanks for your help so far...This is really a stumper isn't it!!! I'm absolutely lost

If I get the same with my car at the same point and after what you done, I would try MAF and idle control valve cleaning procedure. You can find it on this forum.

I swapped the MAF from another car...it was in good working order

I'll try cleaning the ICV

I had leaking injectors. Started with a strong gasoline smell after sitting for 15-60 minutes. Quick repeat starts and overnights were fine.
New injectors cured.
Just put this out for any possible resonance with your situation.

How did you check the injectors?

My bmw indie checked for leaking injectors with a fuel pressure gauge. There was no sign of leakage even overnight. There's no gas smell ever. He did say that the spray pattern could be off causing the injectors to spray the intake instead of directed to the valve. He suggested I run some JB fuel system clean through the tank. So I'm trying that and as how it goes

I checked the icv and its functioning and clean

I don't know where else to go from here

I had a Taurus on the lot that did this once and it was the intake manifold gasket. It would miss the first min or so of idling and then be fine cause the heat would expand the gaskets and plastics to stop the air leak


Supposedly my bmw mech already checked for that though

Any other thoughts would be so helpful

Thanks

Hi again, just another idea about waterpump plastic impeller came off and does not rotate when engine just started. I had that but when temperature goes below 0C. Eventually it will stop rotating with WP shaft when driving and engine overheat as result... And all depends from your reaction next.
May be no much logic for you in this idea but i experienced that and its pretty common for bmw.
Good luck.