Bosch MAF pin outs

[Perry Harrington]

I searched the archives (dl'd to my unix machine) and found these messages:

	Some of you may recall that I've been investigating the possibility of
	swapping a Bosch MAF from a Saab or Volvo (they call it a AMM), for the
	stock  Bosch VAF meter in my Merkur XR4Ti (Ford Sierra in the rest of the
	world).  Here's what I've discovered about the two MAF on the bench:

	'87 Volvo 740 2.3 Turbo MAF  Bosch p/n 0 280 212 007  (black plastic
	case)

	Pin #1  Ground (MAF signal - local)
	Pin #2  Ground for filament burn-off and CO idle adjustment (at PCM)
	Pin #3  MAF output (~1 - 5v)
	Pin #4  Filament burn-off (4v for 1 second after shut-down, controlled by
	PCM)
	Pin #5  12v Power input
	Pin #6  CO Idle adjustment  

	'87 Saab 900 2.0 N/A  MAF  Bosch p/n 0 280 212 005 (aluminum case)

	Pin #1  Filament burn-off (4v fro 1 second after shut-down, controlled by
	PCM)
	Pin #2  12v Power input
	Pin #3  Ground for filament burn-off and CO idle adjustment (at PCM)
	Pin #4  Ground (MAF signal - local)
	Pin #5  MAF output (~1 - 5 v)
	Pin #6  CO idle adjustment

	For bench testing purposes, I was only using three circuits:  The MAF
	output & ground and the 12v input (conveniently provided by a fresh
	battery).  Here's what I discovered:
			Powered, still air              Powered, maximum human breadth
	Volvo MAF                  1.32 volts                   2.70 volts      
	Saab MAF                   1.55 volts                   3.95 volts

	Not surprisingly, the two MAFs are calibrated differently, with the N/A
	Saab MAF likely to max out (5v) with much less air flow than the Volvo
	turbo MAF.

	Now, back to my replacement objective...  The stock Merkur VAF has a base
	starting output (powered but no air flow) of .5v, which is much less than
	either of these devices (relatively speaking).  So I'm thinking about
	sticking an in-line  POT on the output line to provide an adjustable
	base-line voltage and match it to the .5v that the PCM is looking for
	from the stock VAF.  I realize matching the base-line voltage does not
	guarantee a match across the full range, but it's a starting point.  What
	I'd really like to do is find a way to use the built-in CO idle
	adjustment screw, since it will otherwise go un-used since this function
	is not supported by the Ford PCM.   

	If it turns out that adjusting the MAF output in a monolithic fashion can
	not closely reproduce the original VAF output, I'll have to look at a
	"black box" solution from vendors such as Split Second or Pro-M which
	provide the ability to have 2 or 3 adjustments to the MAF depending upon
	the flow.  I'm not smart enough to figure that one out myself.

	Any comments, corrections, open discusions, etc are welcome.

	Brad Anesi
	(bjanesi at juno.com)

And here's Toby's original message:

	I've asked Nick Clark (Imp list and Volvo expert) and he gave me the
	following pin out. Hope it's useful to somebody, Toby

	1 = Earth
	2 = Signal Earth via ECU
	3 =  Variable Output Voltage
	4 = an input from ECU Possible burn off signal after switch off
	5 =  12 volt feed
	6 =  Variable Output from CO adjuster  to ECU

	********************************
	TKMVS at Bigfoot.com
	http://www.kmvs.freeserve.co.uk/index.html
	ICQ 122059845
	********************************

Hope this helps.

--Perry

On Mon, Mar 25, 2002 at 09:38:11PM -0000, TVS wrote:
> > Hello all,
> > I just joined your list because I was looking for some specific
> information
> > I can't seem to find anywhere else and thought someone here might know.
> I'm
> > looking for the pin out specs for a Bosch MAF part number 0 280 212 016.
> It
> > came in Volvo 240 L2.4 from 89-93, maybe more.  I was also wondering
> 
> I did have the pin out for a Bosch MAF, not sure if it was the same part
> number though. Unfortunatly I've lost the email... but I did send a copy to
> the list so it will be in the archives somewhere! Hope this helps, Toby
> 
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-- 
Perry Harrington             Linux rules all OSes.               APSoft      ()
perry at apsoft dot com 			                 Think Blue. /\

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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