Check engine 1222 Light comes on reads lean

[blazing]

My check engine light will come on while idling or holding a steady RPM for a length of time.
I checked the output voltage at the O2 sensor and it was reading below 135mv and it stays low and voltage varies little.
If I rev the engine the light goes off and the voltage cross counts return to bouncing normally for awhile but eventually drop back off and the light comes back on.
When this happens the fuel pressure is at 43 pounds and the engine vaccum is 17 idle is around 600-650 ish
The o2 sensor is a new three wire unit for a mustang wired as per thes instructions

http://www.bmwe30.net/cgi-bin/datacgi/database.cgi?file=articles&report=view&ID=00125&Section=15

Does it sound like a bad o2 sensor or the computer doing something wrong?
Anyone have any ideas ?

[RobertK]

1222 = O2 Rick / Lean Detect.

Could be a bad O2 sensor or a failing FPR. Have you pulled your spark plugs to check for signs of running too rich or to lean?

[blazing]

The plugs look good and the fuel pressure stays where it belongs.
I have recently replaced the
AFM
plugs
wires
cap and rotor
coolant temp sensor
o2 sensor
fuel injectors

[RobertK]

Have you tried replacing the O2 sensor again to be sure you did not recieve a faulty sensor?

[blazing]

Negative.
Mayb I'll throw the old one back in to test.

[87-325ic]

im getting the same problem, Idling for over a minute and Check Engine light comes on until i tap the Revs up..
O2 sensor was replaced not too long ago with a new Stock 4 wire one.
i also get the 1222 code..


Can you tell me how to test the O2 sensor for reading rich/ lean and what the values will mean?

Thanks..

[blazing]

Here is the link I got all my info from.

http://www.kemparts.com/TechTalk/tt07.asp

The signal wire on our sensors is black.
The readings on mine would steadily go down then just stay down.

[BCMike]

My experience with 1222 is twice. Once it was a crack in the intake bellow and once it was a blown intake manifold gasket. The short answer is unmetered air leak is responsibel for this code more times than not.

[blazing]

Update...........
It was the rebuilt air flow meter.
I bought a used one on ebay and installed it, no more engine light and the car is a pleasure to drive compared to the way it was.
Next progect stuffing the rebuilt one up somones touch hole