I just cleaned my MAF because I noticed that one of the 3 little sensors had a black film on it. I was running 110 BLM's before, now that I cleaned the MAF, I'm better than before (up to 119-120 on the BLM's).
I was thinking that cleaning the MAF would mean it would read more air intake, and richen things even more. Can anyone explain why cleaning that sensor would have effectively made the sensor think less air was coming in?

 

If the soil was somehow moist then that could explain it, all the MAF does is sense how much the incoming air changes the temp of the MAF unit (heater), and that is how it estimates how much air is going past it.

 

When the MAF is dirty, it takes longer for it to heat up the resistors which in turn makes the MAF think that the incoming air is cooler than it actually is. Therefore, you may run a little rich, and mileage may go down. Once you clean the sensor, it won't take as much voltage to heat the resistors, so it won't run as rich, and mileage will go back to normal and may increase which it did in my case. I would definately clean it on a regular basis simply because the filter cannot filter everything out. I do not recommend using anything except electronics cleaner, because other cleaners may be to harsh and could harm the sensor.

 

You know what, I think I might just clean my MAF again. As in a previous post, my BLMs shoot straight down to 108 as soon as it reaches closed loop. But since its not throwing a code for a bad MAF, I doubt the unit itself is broken. So I'm going to pull it and clean it...

EDIT:
No difference.