[Diy_efi] Flap type Airflow meters

[Bill Washington]

Torbj?rn,
    Do you know if replacement Hybrid PCBs are available  ...anywhere?
On one of mine the wiper has worn a slot in the resistive section.

Regards
Bill


>
> Subject:
> Re: [Diy_efi] Flap-type Airflow Meters
> From:
> Torbj?rn Forsman <torbjorn.forsman at gengas.nu>
> Date:
> Sun, 21 Jan 2007 14:21:50 +0100
> To:
> diy_efi at diy-efi.org
>
> To:
> diy_efi at diy-efi.org
>
>
> Hi!
>
> Beware that there are no two types of flapper AFMs that have the same 
> calibration. Typically, those intended for microcontroller based ECUs 
> (for example, Bosch Motronic systems, Toyota TCCS, Ford EEC-IV on 
> european cars) have a relatively linear angle - to - voltage 
> characteristic, while those intended for analog ECUs (Bosch 
> L-jetronic, LE- and LU-jetronic, Lucas and various japanese L-jetronic 
> clones) rather have a logarithmic characteristic.
>
> The potentiometer on the PCB is divided into 10 or 12 sections with a 
> laser trimmed parallel resistor for each section. Usually, there are 
> also series resistors at both ends of the potentiometer.
>
> On AFMs for L-, LE- and LU-jetronic, there is a connection to the ECU 
> from a tap at the "hot end" series resistor, on LE and LU the air 
> temperature sensor is connected in parallel to a part of this resistor.
>
> All other AFMs have the temperature sensor connected from ground to a 
> dedicated pin in the connector.
>
> When discussing different AFMs, it is best to mention the part number 
> (Bosch number) of the complete AFM (0 280 20x xxx), the part number of 
> the hybrid PCB (1 288 31x xxx) and the number of the return spring 
> (only the three last digits are stamped on the plastic spring holder 
> wheel, very old AFMs may lack this number). It might also be 
> interesting to note if there is an auxiliary spring that balances part 
> of the main spring's force at idling position of the flapper.
>
> Best regards
>
> Torbj?rn Forsman
>
> Steven P. Donegan wrote:
>
>> Now - if someone can just map those steps to airflow numbers I can make
>> a GM frequency MAF to flapper MAF voltage translation table. Which will
>> allow those of you out there who want to run 80mm MAF's on your (pick
>> engine) car :-) That circuit board is already built - that's my little
>> MAF interceptor project...
>>
>> On Fri, 2007-01-12 at 15:23 -0500, ScottyGrover at aol.com wrote:
>>
>>> Dan was asking about these Bosch/Nippon meters and how they were
>>> calibrated. I put 12VDC between pins 6 and 9 and hooked a voltmeter 
>>> between pins
>>> 6 and 7. I then rotated the toothed wheel on the end of the rotating 
>>> shaft
>>> and  this is what I read:
>>> Base       1.29V
>>> 1 tooth     1.75V
>>> 2 teeth     2.7V
>>> 3    "        4.3V
>>> 4    "        5.3V
>>> 5     "       5.9V
>>> 6     "       6.5V
>>> 7     "       6.8V
>>> 8     "       7.3V
>>> 9     "       7.6V
>>> 10   "       7.95V
>>> 11   "       8.05V
>>> 12   "       8.2V
>>> max         8.21V
>>>
>>> I hope this helps.
>>>
>>> Scotty 
>>
>>
>>
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>
>fi
>  
>