Flapper type mixture screw

[Goughie]

Hi,
I beleive there is a mixture control screw on the flapper type airflow meter, top right allen headed screw? If it is, which way is it to lean the mixture? and is there a starting point, ie screw all the way in and back off 3 turns etc?
Thanks in advance,
Paul

[ramon alban]

Hi,
I beleive there is a mixture control screw on the flapper type airflow meter, top right allen headed screw? If it is, which way is it to lean the mixture? and is there a starting point, ie screw all the way in and back off 3 turns etc?
Thanks in advance, Paul

Turning the airflow meter screw clockwise blocks off the bypass channel and richens the mixture at idle. Turning the screw counterclockwise opens the passage and leans the mixture. As this source of air is not measured by the air flow meter flap the ECU does not compensate for it.

If you think that the AFM setting has been maladjusted previously then 2.5 turns out from fully home is a good starting point

For accurate setting of idle speed mixture a CO meter is needed.

For more information on the AFM go here:

http://www.vintagemodelairplane.com/pag ... ter01.html

[Goughie]

Thats just what i was looking for, Thanks for the advice Ramon, Spot on.
Cheers,
Paul

[bodger]

http://www.v-8.org.uk/forum/viewtopic.php?t=1895

thats what you need , did my EFI flapper , got it done to MOT pass ..

[Goughie]

Hi Again,
Car now running okay and Moted, slight problem though, to get the car to idle at 750ish rpm when hot the idle seems too high when cold, about 1600ish Can this be lowered without altering the hot idle speed?

Secondly, does anyone know where i can buy a "Bugcatcher" air intake for a different 4 barrel holley carbed engine i have? (purely for looks , not performance )
Cheers,
Paul

[ramon alban]

Car now running okay and Moted, slight problem though, to get the car to idle at 750ish rpm when hot the idle seems too high when cold, about 1600ish. Can this be lowered without altering the hot idle speed?

Assuming that you have eliminated all rogue air leaks, from cold 1600 rpm is perhaps a bit too high but it depends how long it goes on for? 10 or 15 seconds would be OK. 30 to 60 seconds not OK. Otherwise what this indicates is too much metered air is getting into the plenum.

To be sure about rogue air leaks do the full range of tests available in my plenum guidelines. It is very comprehensive.

If there is nothing wrong there, then the possibilities for too much metered air getting in are:

Throttle disc(s) not seating properly or too wide open at rest. (depends upon your set-up process).

Plenum idle and breather galleries not working correctly at idle.

Efi Coolant Temp sensor not reading correctly when cold

Extra air valve aperture erroneously enlarged or maybe wrong type of AFM

"Idle speed hangup" that manifests itself more when cold but cures itself when hot. Its a friction issue. See my SD1 downloads for a full explanation.

[Goughie]

Ramon,
Sorry for the late reply and thanks again for the advice, will be out of the country for a week or so and will have a go when i am back and let you know how i get on.
Cheers,
Paul