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How to recalibrate an AFM

 
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BigAl
P4


Joined: 06 May 2003
Posts: 2990
Location: U.K Surrey

PostPosted: Mon Aug 25, 2008 9:42 pm    Post subject: How to recalibrate an AFM Reply with quote

I thought I'd start a new post for this subject


ZeNiTh-PbArM

Quote:
Hi, the easiest way to recalibrate an AFM that has been tinkered with requires another known good AFM. You'll need a source of air flow, like an hair drier or a vacuum cleaner, and make some piping to adjust the AFM to the flow source (use duct tape and plastic bottles).
Adjust flow until the known good AFM has a flap openend about 50%. Measure the resistance on the connector. Using the same flow, calibrate your AFM until you read the same value. Check again with lower flow (drill hole into your piping to release some of the flow) and compare that both AFMs still show comparable measurements.
If you do not have another AFM, or for tuning the AFM to your particular engine, use the above explained procedure, mark the original position of the arm if you're afraid so you can always restore the previous setting. Adjustment of the AFM in the car is made within the hour if you're accustomed to adjust carburettors (feel the effects of the mixture on the idle on a rough to smooth scale)
regards,
zp


BigAl
Quote:
Thanks again ZeNiTh-PbArM
Looking at the connector on the AFM and using the left pin as 1 and the right pin as 5, what pins do I read from to get resistance from the flap?
Also, I just noticed there is what I assume is a thermistor in the top of entrance mouth for air temp, could cleaning this make a difference "brake cleaner?" and do you know the pins for that to also compare?
My Co2 and hydrocarbons are fine on tick over and hydrocarbons are fine on fast idle but Co2 is high. There is a mark on mine but I haven’t got round to putting car on fast idle and moving spring tension yet.
I have a spare AFM but last year when I was going through the same emission testing it gave too high Co2 and hydrocarbons on idle and fast idle, it looks like it has been opened as there is white sealant and clear sealant around and inside it, so I cant use that one as a reference


Need help with this, there are 5 pins and I assume 3 readings, air temp, idle mixture and air flow.
I tested by trying pins 1 through to five, then pin 2 through to 5 ect ect and only noted down if there was a change when moving the flap or the idle mixture screw.

I took a reading on the 20k range and got the following readings, this is off the car in the stationary position.

For the flap

Pins, reading
1&4, 2.09, changed with heat
2&4, 0.06, no change with heat
3&4, 0.38, no change with heat
4&5, 0.07, no change with heat

For the idle mixture

Pins, reading
1&5, 1.76, changed with heat
2&5, 0.01, no change with heat
3&5, 0.36, no change with heat
4&5, 0.07, no change with heat

The following pins gave no change for Idle or Flap

Pins, reading
1&2, 1.81, changed with heat
1&3, 2.17, changed with heat
2&3, 0.36, no change with heat


Help, where do I start???

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BigAl
P4


Joined: 06 May 2003
Posts: 2990
Location: U.K Surrey

PostPosted: Tue Sep 02, 2008 2:10 pm    Post subject: Reply with quote

So i had a play with 2 of the AFM i have, 1 being mine and the other being my spare, the 3rd unopened borrowed one is on the car.

My AFM idle emissions is ok so i thought id look into changing my spare AFM to match up with mine, after playing around and getting the readings for the mixture screw to read about the same I tried it on the borrowed one on my car.
After setting it up, the car was running way too rich, so i set it back to how it was and will set up idle emissions by disconnecting lambda prob and adjusting idle mixture screw.
What a waste of time that all was, but think i have identified the thermistor and idle mixture and possibly the flap.
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BigAl
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Joined: 06 May 2003
Posts: 2990
Location: U.K Surrey

PostPosted: Tue Sep 02, 2008 8:58 pm    Post subject: Reply with quote

Just updating this so its all in 1 post
ZeNiTh-PbArM
Quote:
test 1 : measure resistance between pins 4 and 5 to get air temperature sensor values
test 2 : AFM off the car, put pin 4 to ground and pin 3 to a voltage of 5V.
measure that voltage on pin 2 fluctuates between 0V and 5V when you manually actuate the flap
measure that voltage on pin 1 fluctuates between 0V and 5V when you rotate the CO adjustment screw

ZeNiTh-PbArM
Quote:
with a magnifying glass you can read pin number molded in the ECU connector, pin number is always written on connectors.


REVERSE MY PIN NUMBERING!!!! I GOT THEM THE WRONG WAY AROUND
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