Hi guys! I have been stumbled with this issue for a number of months, and still it does not find any explanation in my mind, WHY:
when it is wet and rainy weather, and a couple of days after that, KA 24 de engine runs soo good, extra 10-15 hp I’d say! In dry days, however, it sounds like its overheated, saay like wires scrapping on the metal when it goes to higher rpms, and it does not want to go fast. Anyone knows what’s this?
Atmoshperic pressure? Density of the air? IDK, take physics or something.
So, you say atmospheric pressure affects such things as timing, and overall engine performance by that much? Lol! I silently sit in the corner with my grade six physics book, and study hard:)))))))))))))))!!
Yeah he’s kinda right. When it rains the air is a lot more dense, and we all know what that does for performance (think cold air intake). It takes a few days after a good rain for the pressure to lift. Any motor will run better with cooler, denser air; sometimes a night and day difference 
-Bill Nye the science guy
Yeah… The less dense the air the less engines run happy. When you own a turbo’d or N/A car, and it’s like 40* outside, if you don’t have proper ducting or a proper cooler set up, your car gets heat soaked. Heat soaking is essentially your motor turning into a hot air pump. It’s sucking down less dense and hotter air, which means the intake charge is hotter and therefore there is much less oxygen molecules and too much gasoline molecules (PPM of each per cylinder essentially; colder air/gas will burn more easily than a hotter gas/air mix. Which in turn means combustion efficiency goes up resulting in more power.) That’s why on cold days an N/A or turbo car will run much better, hence why people make such a fuss about cooling the intake air temperature.
L-O-L
Ok, what you say is 100% right, BUT: It’s not only that. Because, In Winter. -15 C! Air is F^%$kin cold, so, it’s really dence, right? But it’s dry at the same time. So in those condition KA24de still runs nearly as shitty as in dry summer day! However, when it’s ±3, wet and rainy, it runs beautifully… WHY?? No idea… My guess would be, that the air system, with all the sensors and valves works differently, and different ECU settings are applied. As for some pros here, except for physics, it might be a good idea to check on electronics and grade 5 computer science as well, although meteorology knowledge seems to be ok)
First of all the sensors work in unison, that being said the ecu will adjust to what ever the sensors signal voltage is. All this information is then stored in the RAM where the ROM will send the intrustions. For example the O2 sensor will have an output voltage varying from 0-1v, this signal will be sent to the ecu and the adjustments will be made to the injectors etc. Depeneding on the signal.
And sanders essentially answered your question.