[Diy_efi] MAF calibration

Perry Harrington pedward at apsoft.com
Sun Aug 18 14:21:54 GMT 2002


On Fri, Aug 16, 2002 at 01:48:57PM -0600, Heath, Tom wrote:
> Forgive me if this has been discussed before.  I'm a newbe here, but I have
> been searching for several days now with no success.  
> 
> Here is what I'm doing:
> 94 Ford 2.0L, EEC-IV ecm, with a MAF.  I'm going to turbo this engine.  
> I believe the trick to compensate for larger injectors is to recalibrate the
> MAF sensor.  Now, I'm a mechanical engineer, so changes to the ecm program
> are beyond me at this time.
> I calculate that I need 300cc/min injectors, this is 36% larger than the
> original 220cc.

You could give pro-flow a call, they do MAF recals for $100.  You could also
invest in numerous electronic methods (EEC-Tuner, TwEECer, custom chip).  I
would locate a plug compatible MAF that flows the correct amount of air at
the resolution you want and have a custom chip made.  This is trivial stuff
to do for a chip dealer.  However if you need to tune it, then it is more
difficult.  Tuning it yourself requires knowledge of the EEC-IV computer
and an EEC-Tuner or TwEECer.

Is this a Zetec ZX2 motor?  What's the computer catch code (on the harness
connector in big letters, eg A9L, A3M, DA1).

> 
> Question 1) Has there been any work done on a DIY MAF recalibration?

Not that I know.  There are adjuster devices put in line with the MAF to tune
the low and high outputs.

> 
> Question 2) Is a change to the basic MAF size a viable alternative (see
> below) or is my logic flawed?
> 	By doing some quick air flow calculations  CFM=(CID x RPM x .5 x
> Ev)/1728
>     Alternative 1, maximum air flow
> 	I find that a MAF from a 3.8L (Taurus) should flow the required
> maximum 230cfm I need with a pressure ratio of 1.54 on the 2.0L.  However,
> at idle the cfm is 89% different (46.8cfm for the 3.8, and 24.7 for the
> 2.0).
>     Alternative 2, idle CFM plus 36%
> 	Solve for CID at idle plus 36% CFM (to compensate for increased
> injector size) is 	approximately 166CID (or 2.7L).

Pro-Flow has done most of this work.  They recal MAFs for injector sizes.  If you
want to go this route (not the best, but it works for some people), then get
a suitable sized MAF (Mustang 5.0) and have it recal'd by Pro-Flow according to
the new injector size and old injector size and the old MAF flow values.  They
need to know 4 things: Current MAF transfer function, current injector size,
intedend injector size, and intended MAF to use.

> 
> Thanks for your help.
> 

--Perry

-- 
Perry Harrington			Data Acquisition & Instrumentation, Inc	
perry at dainst dot com					 http://www.dainst.com/

Those who would give up essential liberty to purchase a little temporary safety
deserve neither liberty or safety. Nor, are they likely to end up with either.
                             -- Benjamin Franklin

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