Maf only tune?
On The Tree
Joined: Apr 2011
Posts: 181
Likes: 1
So how does the maf respond to transient changes accurately without ve? If you stab the throttle doesn't it take time for the air to reach the maf and compensate?
To answer your question, I think of it like this:
You have a 14 foot hose full of water that is pumping through at 9 gallons per hour (we'll call this idle). You measure the flow at the 2 foot and 12 foot marks. Now, let's assume someone flips a switch to change the flow to 250 gallons per hour instantly (we'll call this WOT). The pressure change is going to push the water that's already in the hose through. It's not going to have to wait for the 9 gallon per hour water to get out of the way. It's the same density, same mass, etc. So, what you measure at both ends of the hose should be equal.
Same goes for airflow in our intake system. Only difference is, it's being sucked in - not pushed (unless your forced induction). As long as your measuring the flow at a stationary point in a closed system, it shouldn't matter.
**Disclaimer** I'm by no means fluent in the theories of flow dynamics, but I'd be surprised if this example is off. If it is, I'd love to know why.
Water's fluid mechanics don't apply for air, because water can't be compressed but air can. So a transient can cause vacuum, turbulence and other things that don't happen with water. You need to tune the MAF if the intake pipe is longer than stock, because the longer it is the bigger the effect will be under transient conditions.
