-10 degrees, dies when in neutral

[///m42 sport]

So this just happened to me tonight suddenly after work.  will idle if I give it gas, and drives fine but if I have to stop at a light then all the lights on the dash come on and it stalls.  Had to drive home this way.  Is fuel delivery a usual suspect?  Or vacuum leak?

[bmwman91]

My bet would be on a gunked up ICV. The oil vapor from the PCV system coats everything in the intake, and as far as I can tell that is one of the main reasons for why the ICV door gets sticky. In cold weather, that stuff gets extra sticky/thick.

[///m42 sport]

I plan on cleaning it with brake fluid.  What would I use to relubricate it?

[DesktopDave]

IMHO - I wouldn't lube the ICV at all in really cold weather, and brake fluid isn't a good cleaner. Did you do a stomp test to see if the car has any codes?

To test the ICV, get a 9v battery and put it on the terminals. IIRC the valve should audibly 'snap' closed...and not slowly. If it's pokey, clean it out with a toothbrush and some isopropyl until it snaps shut. Also check the hoses - if there are any cracks at all, replace them. I deleted all the TB heater hoses and upgraded to silicone rubber hose from an EBay guy, that seems to have fixed the hose problem permanently.

I'd soak the valve body part in iso alcohol since it's cheap, effective and isn't all that poisonous. It also won't damage any electrical components like the ICV actuator motor if it gets in the upper part of the ICV case. You could also use TB or carb cleaner too - just don't inhale too much or get it on your skin...those VOCs are some nasty stuff.

You could also have a vac leak in there somewhere - they're a common problem. It could also be:
bad coolant temp sensor
dirty/misadjusted throttle plate
broken TPS
sticky AFM door
gunked up injectors
water in your fuel tank from a bad expansion tank or valve

[colin86325]

If the dash lights are coming on before the stall occurs, this indicates an electrical issue.  Does the ABS light come on?  If so, then you probably should have a look at your charging system.  The cold weather is hard on a battery, and a marginal alternator will not have the umph to charge a battery in cold weather.  Hopefully it will be just the voltage regulator, as it is cheaper.
An alternator will typically put out more voltage at rpms above idle as well.
 

[///m42 sport]

Now that you mention it, I do notice the dash lights come on right before it dies...the idle would flutter a little below 1k, then dash lights would come on then engine dies.  I can usually restart it right away though and is fine if I keep the revs up.  I have a newish interstate battery though.  Will have to check on the alternator bushings.  THnx!

Also I notice that this happened when it was -10.  was fine with it was -5 degrees out.

[colin86325]

Hope you mean brushes/voltage regulator, not alternator bushings! 

Yes, it would make sense to check your alternator output.