I know it's been hit a thousands time I just can't find the info I'm looking for I have an mci 8 and I'm trying to see how much air bleed off is normal I would love for some tune frames on building air and how long it bleeds off.
Are you talking about the pressure shown on the gauge or how long it takes for the air suspension to settle?
My bus will hold air on the gauge for a few hours before creeping under 90psi, and then it will drop to about 40-50 by the next morning. The air suspension will stay up for months.
A really good place to start is to learn how to do an airbrake/air system safety leak down test. Lots of good information in the CDL manual and lots of good information online.
These tests will give you a specific number of how many PSI drop is permitted in a minute, both while holding the brake pedal down and while the bus is just sitting.
Here's one example: https://www.youtube.com/watch?v=MbnVGWqDHIU
Mine drops to 90 in 3.5 hrs
And is at 30 psi in 18 hrs
But my suspension starts dropping once it drops below 90.
It holds 30 for months