[Gmecm] runing two MAF meters

[Jay Vessels]

Hi there!

I would guess two MAFs would require some pretty funky air cleaner 
ducting; an example would be two air cleaners ducted through two MAFs 
into a Y into the intake, or perhaps two air cleaners/MAFs, each one 
plumbed into half the engine?

If your MAF outputs are 0-5V (i.e. L98 TPI) and that is what your ECM 
wants, then I'd guess some sort of op-amp that would average the two 
readings would work.  Sounds easy, though you'd have a lot of work in 
the cal. to get it right.  I could see some flow bench work in your 
future (which is an excuse to build that DIY flow bench!).

If your MAF output is a variable frequency, the easiest method that 
comes to mind is a PIC or similar microcontroller.  Let it read the MAF 
data from each sensor and generate an appropriate output frequency.  The 
benefit here is that you could use, say, LS1 MAFs and feed your LT1.  Or 
let your PIC generate a variable voltage and use those LS1 MAFs on your 
L98.  Nice thing about a micro is that you get to mix 'n match to suit 
your needs.

Jay Vessels
1982 Chevrolet S-10 Sport, 2.8V6 TBI
1984 Chevrolet S-10 Blazer Sport, 2.8V6 carb. (for now)

Jeff Stevens wrote:
> You are correct, at least for the LTx and LSx MAFs I'm familiar with. A
> divider would have to calculate an representative "average" value of the
> two frequencies.  What makes it harder still is that the MAF frequency
> output curve is not a straight line, so a simple average of the two values
> will not yield a precisely accurate result.  Might be good enough, though.
> 
> I looked into building a simple divider using 3 frequency <-> voltage
> converters and a voltage averaging circuit, but the pain involved with
> plumbing 2 MAFs was too great.     -LJ
> 
> ----- Original Message ----- 
> From: <bryan_es at yahoo.com>
> To: <gmecm at diy-efi.org>
> Sent: Thursday, July 07, 2005 11:16 AM
> Subject: Re: [Gmecm] runing two MAF meters
> 
> 
> 
>>It's been done. Someone on ls1tech did it a few years
>>ago. Don't remember the details however. Please
>>correct me if I'm wrong but doesn't a the frequency
>>what is measured by the pcm for MAF value? I want to
>>say I remember it being more complex than a simple
>>voltage divider.
>>
>>
>>>i thinking today and was woundering if this would be
>>>possible; running two MAF. could you just wire them
>>>in series and then divid the proper voltage table in
>>>half. kinda like going from a 1 to 2 or even 3 bar
>>>map and re scaling the tables?
> 
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