Air/Fuel ratio adjustment?

[prototype]

Where's the mixture screw on this stupid thing? Even with the AFC lines hooked up on my carb it's running too rich according to my A/F ratio gauge... Its one LED shy of being pegged out rich just under normal acceleration.. I understand running a little rich during hard acceleration, but not all the time.
I've done a lot of searching and lots of topics talk about it when adjusting the idle speed, but never really show ap icture of where it's located.
:: is confused ::
Thanks everyone.

Thanks..
It's a sun something or other... It's from autozone.. $30. Using the stock 1 wire O2 sensor.
Suckzors that the screw is inside the carb... Joy Unspeakable...
How does the AFC work anyway?

That little black TEC block with the 3 vacume lines that run to carb.. does it adjust the vacume based on barametric pressure or something?

[A20A1]

what kind of sensor are you using and that typre of A/F guage are you using.

Note that the exhaust cools down and gives faulty readings sometimes... also there is a delay in the read time from the actual mix.

The A/F screw is for idle mix which does have impact on acceleration mixture.

Also you want to check your ignition system and the wiring to rule out falutly signals.

Is this a stock carb or did you remove the vacuum lines?

the mixture screw is deep inside the base of the carb, remove the carb and the rear bracket on the carb to acces the cap that is covering the screw... remove the cap, reinstall the bracket and reinstall the carb... now you can turn the screw.. I used a "eyeGlass" repair screw driver sew because they had the tuny screw drivers I needed to fit inside the hole and adjust the mixture while the carb was running.


My proceedure for adjustment is here:




Make sure the o-ring on the A/F screw is good... also there is a spring and washer in there.

Try dropping the idle down as low as you can go, make sure the car is in neutral/park, the accessories off, the coolant and engine warmed up fully. Choke off (Fully Open), or removed... also note you may need to disable the throttle controller / idle diaphragms if idle doesn't drop.

Try to get below 500 rpm idle.
Then while the car is idling adjust the air fuel mix screw.
You want to try and turn it in all or most of the way first before you turn it out.

It's difficult to tell when the needle is seated (closing off the fuel passage all together).
It's such a fine thread and the seat is aluminum so it's easy to dig in and or strip the threads and go further then you should, especially if you have a lot of leverage on the tool you're using to adjust the A/F screw so be careful.

When you got the screw in and the idle below 500 or as close as it can come.
The throttle plate should almost be completely closed.
Make sure your float level is correct before begining the proceedure.
Also make sure you don't have a vacuum leak or igntion or fuel problem.

Now adjust the screw.

You should notice the effects of turning the screw. Listen to the carb as well as the rpms... they should vary as you turn the screw in/out.

You usually want to leave the screw where the idle stops going up... or right before it stops.

Say you were turning the screw in (clockwise), leaning the mixture then you notticed the rpms drop, so you turn the screw out (counter-Clockwise) richening the mixture and the rpms go up. Stop when the rpms don't go up noticably from the last time you turned the screw then turn the screw in (clockwise) just a little and you're done.



AFC?

the AFC is only on EFI.
Air Fuel Controler

You mean the AJC not AFC

[Kabuki]

The boss says that the TEC box is only for adjusting the air bleeds on the high altitude or Cali cars. Oh, and don't fuck with the lambda screw in the carburetor. it'll never run correctly again. If you really want an A/F meter, get a wideband oxygen sensor unit. The stock O2 sensors aren't worth shit for that.