FW: MAF Upgrad

[James Weiler]

Time for my $0.02.  As I understand your MAP is a voltage output and the 
MAF is a frequency output.  If you want to run two MAF's adn you want to 
send the resulting signal to where the MAP used to be then might I 
suggest using Ford MAFs.  They output volts not freq. and thus no fancy 
converter would be needed.  Problem is that their voltage vs. air flow is 
not linear.  Well it is for the first part but then it approaches 5.0 V 
asumptotically. (i.e. it's geometric).  I don't know how to build a 
circuit that would take the two voltages and put out an average in this 
case.  It might be easier to just have one MAF supply voltage (and the 
other is a dummy) and just change your tables to compensate.  i.e. assume 
that twice the amount of air is entering the engine as the MAF says there is.

HTH
jw
P.S. let me know how you solve this.  I'd love to use two small MAFs 
instead of buying an expensive large MAF.


On Mon, 23 Feb 1998 lkurek at smtpgate.anl.gov wrote:

> 
>      Now this is a cool idea!
>      
>      I could get an elbow (tee) fabricated that has one MAF going off to 
>      the left, and another to the right, with dual K&N's hanging off either 
>      side. Sure would look nice and run much better....
>      
>      Now, how would we go about building this "interface" box? I would 
>      assume all it would take is some circuit to do a simple averaging of 
>      the MAF sensor output (assuming it is a rising voltage type circuit). 
>      If it was a wave output, wouldn't you have to synchronize and add the 
>      two frequencies together to generate a sum?
>      
>      Just wondering....
>      
>      TTYL!
>      
>      Larry Kurek
> 
> 
> ______________________________ Reply Separator _________________________________
> Subject: FW: MAF Upgrad
> Author:  <diy_efi at efi332.eng.ohio-state.edu> at Internet
> Date:    2/23/98 1:33 PM
> 
> 
>      
> How about running two MAF sensors in parallel?
> I'm sure you'd need some kind of happy box to interface the two 
> and send out an integrated signal.  If there were enough interest, 
> this could be a source of income for somebody ...
>      
>  Dave
>      
>  ----------
> From:  Peter Fenske
> Sent:  Monday, February 23, 1998 4:42 AM 
> To:  diy_efi at efi332.eng.ohio-state.edu 
> Subject:  Re: MAF Upgrad
>      
> Hi Larry
>      
> I have looked at using the LT1 maf on my 86 MAF. 
> The LT1 is FM vs the 86 Bosch analog.
>      
> Several people have used the Porsch Mafs bigger but mucho dollaro 
> And it is just a small matter to modify correction a wee bit.
>      
> The LT1 FM is possible since the V8 TPI code has an appendage 
> left over from the V6 FM maf. Most of the freq handling code 
> is there. The tables would have to change a bit.
>      
> However with the 89 with Vats there is a wee problem. 
> The Vats freq measuring pin is used by the V6 to measure
> maf frequency. So you would lose your Vats a terrible thing.
>      
> Anyways the software is quite a mess. Just saying it could be 
> done..
>      
> And MAP ain't too bad.
>      
> In addition there is provision for N-alpha in the code 
> Ie rpm and tps. This is the backup code section
> for the Maf
>      
> later:peter
>      
> >
> >      MAF is a better system theoretically than a MAP system. The reason   
> for
> >      this is that you are MEASURING airflow/density rather than   
> calculating
> >      it. In practice, a MAF system is harder to package and there is an   
>      
> >      inverse relationship between peak airflow potential of the MAF and   
> its
> >      accuracy. The stock GM 3" sensor (i.e. 85-89 TPI) is fairly   
> inadequate
> >      for a healthy motor (325+hp)...it just won't flow enough air. If I   
>      
> >      could somehow get a late model 3.5" MAF to work with my 89
> >      harness/computer....that would probably be best...but I have no   
> clue
> >      if/whether this would work.
> >
> >      TTYL!
> >
> >      Larry Kurek
> >
>      
> 
> 
>