mrx

Hallo,

at the moment i'am working on my maps. and i noticed yesterday that the mixture in an area in which i had 14:5-14:7 tha last days... now is about 13.5-13.8

is this normal? when i had 14:1 mixture the weather was warmer then yesterday (about 3-7°C ambient temp difference) and it was dry... yesterday when i had 13,5:1 it was colder and it had rained yesterday... are this normal ranges for a mixture change effected by the weather? or do i have to search another way...

everything else is the same... same street, same throttle position, same rpm, same map pressure, same wideband o2, same coolant temp, only the air intake temp is cooler because if the lower ambient temp...

but as far as i know, with lower air temp, the air has more oxygen and so with the same amount of fuel the mixture must be getting leaner instead of getting richer or did i forgot something?!

closed loop is also disabled so this can't be the reason for the changes in the mixture.

Greets
Malte.

pngfolife

A/F will change slightly as humidity changes. Don't forget that water is not oxygen and the more of it in the combustion chamber, the less room for actual O2 molecuels. Most likely, the change in humidity was much more drastic than the difference in temperature. A few degrees temperature difference will not change air density enough to negate the effects of the increased humidity. If the weather were even colder, maybe 15-20 degrees cooler, that's a different story...