Rough idle/stall on cold start

[dyintorace]

Folks,

I continue to work my way through my new (to me) ZHP (2004 sedan, 80k miles) and various and sundry issues. I've come across the latest and could use some collective wisdom.

Recently, I had the car reprogrammed by the local BMW dealer, to address a stutter under throttle while in 5th or 6th gear and a tendency to want to stall when decelerating into a stop while clutched in. Good news...both issues were solved. The bad news is the car immediately developed another habit. When starting the car while cold (overnight or anything longer), the car will start, start to idle roughly and then either catch itself or die. Usually, the longer it's sat, the more likely it is to die.

I have the car at my mechanic's currently. I had already planned on having him change all the fluids (already did the oil, now he's on to the trans, diff, brake, coolant, steering) as well as replace a leaking pinon seal. We also decided to change the fuel filter, given the car's mileage. He experienced the cold start issue (it died on him), so he took it to the dealership for me, thinking it is a programming issue.

While that is going on, I'd love your thoughts on what it could be. Any thoughts??

Thanks, Tucker

[danewilson77]

ICV.

Unrelated... Have him check disa as well.

Are you changing plugs?

Maybe check fuel pressure at the rail?

HTC Thunderbolt+TT

[dyintorace]

ICV.

Unrelated... Have him check disa as well.

Are you changing plugs?

Maybe check fuel pressure at the rail?

Plugs were changed at Inspection II, not terribly long ago. I'll offer the other suggestions though. Thanks for the ideas!

[CERF04ZHP]

I'd like to resurrect this one if I may... Experiencing nearly the same symptoms, except I haven't stalled yet. Every cold morning that I start it, it drops down to 500-600 rpms and coughs/chugs a couple of times, then jumps back up to a normal "cold" idle. If I stab the throttle quickly right after I start it, I can avoid the temporary low idle. Replaced fuel filter approx. 20k ago, I'm thinking replace DISA/clean ICV? Plugs haven't been done in 60k+ either... Mayyyyybe do those too?

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[alexandre]

I'm having the same problem with new DISA, clean ICV, intact intake boots, 20k miles plugs, < 20k fuel pump and filter, Techron 2k ago and < 1k oil. (I didn't do all of this to fix it lol it's just the state of my car currently)

Starts at 1100, drops to 800, up and down 800<>1100 and stabilizes at 800 after. ICV did a huge difference - it only 'coughs' twice until it stabilizes, while it struggled 6-7 times before. Improved MPG as well. Takes 45 minutes, just do it

Next steps are O2 sensors, which are original (and thus due twice already on my car based on BMW's recommended replacement interval), reverting my ECIS CAI back to a stock airbox with a new filter. I also need a DME upgrade to the latest version. If you want to check your O2's the manufacture date is on the connectors under the engine cover.

Let me know your progress - I'll do this as well.

[CERF04ZHP]

I'm having the same problem with new DISA, clean ICV, intact intake boots, 20k miles plugs, < 20k fuel pump and filter, Techron 2k ago and < 1k oil. (I didn't do all of this to fix it lol it's just the state of my car currently)

Starts at 1100, drops to 800, up and down 800<>1100 and stabilizes at 800 after. ICV did a huge difference - it only 'coughs' twice until it stabilizes, while it struggled 6-7 times before. Improved MPG as well. Takes 45 minutes, just do it

Next steps are O2 sensors, which are original (and thus due twice already on my car based on BMW's recommended replacement interval), reverting my ECIS CAI back to a stock airbox with a new filter. I also need a DME upgrade to the latest version. If you want to check your O2's the manufacture date is on the connectors under the engine cover.

Let me know your progress - I'll do this as well.

Will do, thanks Alexandre.

[johnrando]

Beside the DISA, fuel stuff, etc., it may sound crazy but check your battery. A weak battery can wreak havoc on these cars, including producing a rough idle. Go figure.

[danewilson77]

OBC whatcha go?

[CERF04ZHP]

Beside the DISA, fuel stuff, etc., it may sound crazy but check your battery. A weak battery can wreak havoc on these cars, including producing a rough idle. Go figure.

Did not know that.

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[alexandre]

Battery's a month old on my car. Did make a difference on the car's behavior at startup.