I've never really thought about this, but I thought it would be worthy of discussion. I just drove around for an hour in the rain and got a good data log, I'm curious to see how it compares to the datalog on a cool dry winter day. My co-workers husband is an atmospheric scientist and I'm going to ask him a few questions. I believe a given volume of air will have the same oxygen content no matter what the humidity of that air is? Same with altitude, a given volume of air will have the same oxygen content at low pressure and high pressure, however pressure will effect how air is being pumped in and out of the engine. So how would a higher moisture content effect the voltage of my MAF? Water has a better specific heat (heat transfer ability) than air so I would think the voltage should change faster. But if the oxygen content is the same for a given volume of air being introduced the MAF shouldn't be effected. The scientist in me is thinking that with a higher humidity an extra amount of moisture/water is being introduced into the combustion chamber. Wouldn't this lower combustion temps and effect the exhaust leaving the chamber? It would be interesting to take two new mustangs, one driven in a cool winter desert and the other driven in Seattle and see how the EEC adapts to those conditions. Just some thoughts, any opinions or comments are welcome.