Stock setting for AFM screw on FI car

[whiterabbit]

Going through the book page by page fixing little stuff. I notice someone removed the metal cap/plug from the CO adj screw on the air flow meter. What is the stock setting? How many turns from seated? I think it might be the reason my idle adj Screw has to be almost all the way out almost past the o ring to idle. Then it won't idle under 1100 rpm.
Thanks all.

[Kevin1]

Everyone who owns a FI spider should print out and keep a copy of this article with their service books. Many thanks to the author, Greg Gordon. It is the best write up for servicing the L-jet system I have found.
http://www.hiperformancestore.com/Ljetspider.htm
It explains, in a step-by-step manner how to "tune-up" your L-Jet fuel injection system.

I have never seen a stock setting listed for the CO screw as a number of turns. The procedure to set it is quite simple, but it requires the use of a digital multimeter. This is the last adjustment to be made after everything else is set correctly. Before you can make this adjustment the throttle plate stop, idle adjustment screw, throttle position switch, etc. all have to be correct. The instructions in the article use an Alfa as the example, but it applies to the Fiat, too. Follow it through carefully from beginning to end and you will have a much better running car.

[bradartigue]

Wont' idle under 1100 RPM is more likely an air leak than that CO adjustment screw. If you were to cut open an AFM and see how that thing works you'd understand how miniscule an adjustement it really is. If you think it is causing the issue then count turns in (closing it) or out (opening it). In = air bypasses metering, leaning the mix; out is opposite. Very minor changes, measurable by sniffer or multimeter on the O2 sensor.

Has your AFM cap been opened? Owners sometimes adjust the AFM flap tension under the mistaken impression it will improve acceleration; if so, the rod that activates the fuel pump may have been modified, turning the pump off too early in the flap rotation.

[whiterabbit]

That's where it get me confused. It has you run the idle screw all the way in then out till you reach 800ish rpm the adj the throttle stop to 800-900ish rpm. Do you start the process with the throttle plate fully closed with the bolt and lock nut backed out,start car and turn idle screw out till you reach rpm? The idle screw is a jet or enrichner? After adjusted then you set the throttle sensor to 0ohm or set the sensor to 0ohm with the throttle plate fully closed prior to messing with the idle? I have the factory manule only. Guess I'll print the other you referenced too.

[rlux4]

The throttle plate acts to allow more or less air to pass throught the AFM. As it opens the increased air volume opening the flap in the AFM signals the ECU to compenstate for the increased air intake with more gas (the injector pulse is longer in duration). At full closed it isn't an airtight seal and some air is being drawn in, it shouldn't take very much opening of the throttle plate with the adjustment screw to achieve idle range.
As Brad said, if you're having trouble getting your car to idle in correct range, check for air leaks in all the intake components past the AFM. Air leaks= unmetered air. Unmetered air = air the ECU can't take into account.
Ron