[s-cars] Re: [Es2] MAF to intake side of turbo

[Elijahallen92 at aol.com]

Rich,
 Thanks for the thoughts, this makes sense so I will make sure to have  all 
my plumbing very tight before moving the MAF. All this input is very  valuable 
so keep it coming. Thanks to everyone so far.

Elijah
 
 
In a message dated 6/5/2005 10:56:50 AM Eastern Standard Time,  
richard.tanimura at gmail.com writes:

Elijah,

This has been done before. It works but you lose the  ability to detect
air leaks.

The MAF in it's original position is  used by the motronics to detect
air leaks in the boost tract. It works like  this. If the MAF measures
a large mass of air passing through it, but the  MAP measures only
small increases in boost pressure, the Motronics  logically assumes
that there is a leak somewhere. The Motronics pulls the  emegency
brakes and cuts fuel. This is the famous MAF cutoff. Mihnea taught  me
that.

Second, is an interesting automatic control problem. Say  you put the
MAF just before the throttle body and you get a leak upstream  of the
MAF. What happens?Your MAF and MAP see low flow and low  boost.
Motronics interprets this as a signal to spin up the turbo more.  It
will close down the WGFV more to increase boost to try and reach  the
target boost. Because of the leak, the MAF and MAP still measure  low
flow, low boost. Motronics spins the turbo up even more. And so  forth
in an upward spiral. The result is an unstable regulation loop.  This
bit is something I deduced myself from the little automatic  control
theory I know. It could be completely wrong.

So IF you move  the MAF and IF you get a leak upstream of the MAF, I
think you may have  trouble. You decide whether the risks are
acceptable for  you.

Rich

On 6/5/05, Elijahallen92 at aol.com  <Elijahallen92 at aol.com> wrote:
> Hey guys, I've been reading about  a few guys in the UK moving the maf to  
the
> intake side and  having no issues. Anyone done this yet here? I am thinking
> of moving  mine to the intake pipe just before the intake manifold right 
before
>  where the ISV goes in. This will let me free up the turbo cold side and go 
 to
> a  4" intake. Thanks for any input.
> 
>  Elijah
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