Hi All,
I have a 2000 MPV LX with 105K miles. The weather has turned colder here and it's not running very well since. When the weather is below freezing, the idle bounces all over (along with stalling, loss of braking, etc). I had the same problem last year and replacing the battery seemed to fix it, but apparently not (battery checks out). Today (coldest day this season -- 20 degrees) it was even worse -- stalling usually at idle (though once while "accelerating" uphill). I'm seeing lots about IAC and MAS issues, but nothing specifically addressing it as an issue in cold weather only. It does not get better as the car gets warmer. The car accelarates fine generally and drives fine (except for the potential one time today uphill). The check engine light is on as well with the following codes read today:

P0171 - fuel trim bank 1
P0174 - fuel trim bank 2
P0300 - Cylinder misfire detected
P01170 - H02S-11 No Change detected
P1173 - H02S-21 No Change detected
P1512 - VTCS stuck closed

Any experts out there who have an inclination what is the likely culprit? I know where the IAC is and how to replace it. Where is the MAS sensor if that is the likely cause? I'm leaning towards changing the IAC... Thoughts?

Thanks.

Mike

 

I did find this service bulletin also that seems to be even more likely....

http://www.mpvclub.com/tsb.php?id=146

Does the colder air worsening the condition if this is the problem (either making the gasket more susceptible to air leak or the denser air???)