Barometric pressure?

[JustinR]

Hi All,
Was after a bit of guidance on barometric pressure effect on idle on my 02 STI 2.35.
Car idles around 0.95 lambda during fine weather but idles very lean around 1.07 to 1.09 during wet/stormy weather, which means it often stalls at junctions etc. This has been happening for about a year now so I'm wondering if I have a sensor failure.
The BAP reading is always sat at 955mbar on SCal and BAPv gives no reading at all. Should this be working and therefore making barometric fuel corrections or am I barking up the wrong tree?
I don't run wideband at idle btw, only once on the move so car runs target lambda perfectly. Just idles very lean in foul weather.
Any advice much appreciated.
cheers
Justin

[TimH]

Without a BAP sensor (which very few installs have), the BAP measurement is taken from the MAP sensor at start up...but that has to be turned on.

Look under sensors, then the BAP sensor and there's a "key on" setting that needs to be enabled and set to take it from the MAP sensor.

Worth checking I would think.

[JustinR]

Hi Tim, Jay here, hope all ok with you
Thanks for that, was thinking there might be a OE BAP sensor in the car which syvecs would pick up from the standard pinouts but obviously not the case.
OK, have checked BAP sensor and Key-on is enabled but not sure how to check if its reading from MAP

[TimH]

Hi Jay...thought it was you

Under the "key on" settings check that "source" is MAP1A. It probably is. But it shouldn't always read 955, so something's not right; mine varies from log to log.

[JustinR]

Ok thanks...yep is definitely on MAP1A so thats good. However, is definitely showing BAP of 955 all the time on SCal so perhaps thats what's causing lean idle in bad weather
Thanks for the steer Tim, much appreciated