[Diy_efi] Flap type Airflow meters

[Torbjörn Forsman]

No, I have never seen any replacement parts for such AFMs. In your case, 
a temporary fix could be done by bending the wiper so that it contacts 
the carbon somewhat offset from the worn slot. What part number has your 
hybrid? Maybe it can be found in any relatively common AFM.

Best regards

Torbj?rn Forsman

Bill Washington wrote:
> 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
>>  
>>
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