Per my previous threads,

https://www.6speedonline.com/forums/...ighlight=p0175

and

https://www.6speedonline.com/forums/...ighlight=p0175

I have been getting a P0175 (System Too Rich (Bank 2)) and now recently, a P0172 (System Too Rich (Bank 1)) CEL.

However, it only seems to happen when there is rain on the roads, rain outside, VERY humid, etc. I have pretty much narrowed it down to my MAF, but I am curious as to why the weather seems to affect the results so much. Could my MAF be getting a "slight" coat of water droplets enough to affect the readings? I am on the stock air filter that is no more than 4,000 miles old (put on by Porsche for my 30k service).

Warm weather = no CEL
Wet, humid weather = CEL after spirited driving

During rainy weather: Long term fuel trims are positive by 4-5 percentage points on both banks equally and under idle, when the CEL is triggered, short term fuel trims on both banks are -17 to -24 percentage points (trying to lean out the condition which has the computer thinking that my car is running too rich - hence they CELs.

During dry, warm weather: The LTFT and STFT are all w/in spec and show no signs of really struggling to correct lean/rich conditions. Go figure.

Probable causes...
♦ Incorrect signal from MAF sensor (My thought is that this is the problem, personally)
♦ Fuel pressure too high
♦ Fuel injector leaking
♦ EVAP canister purge valve open

Any ideas? Perhaps this gives some more insight? Stephen?