With Speed Density Update

Flowchart Code 44:

Wiring Diagram:

CIRCUIT DESCRIPTION
The ECM supplies a voltage of about 0.45 volt between terminals "E14" and "E15". (If measured with a 10 megohm digital voltmeter, this may read as low as 0.32 volt). The Oxygen (O2) sensor varies the voltage within a range of about 1 volt if the exhaust is rich, down through about 0.10 volt if exhaust is lean.
The sensor is like an open circuit and produces no voltage when it is below about 315 °C (600 °F). An open sensor circuit or cold sensor causes "Open Loop" operation.


TEST DESCRIPTION
Numbers below refer to circled numbers on the diagnostic chart.

1. Code 44 is set when the O2 sensor signal voltage on Circuit (CKT) 412 remains below 0.2 volt for 60 seconds or more, and the system is operating "Closed Loop."
DIAGNOSTIC AIDS
Using the "Scan," observe the block learn values at different rpm and air flow conditions. The "Scan" also displays the block cells, so the block learn values can be checked in each of the cells to determine when the Code 44 may have been set. If the conditions for Code 44 exist, the block learn values will be around 150.

(O2) Sensor Wire
Sensor pigtail may be mispositioned and contacting the exhaust manifold. Check for intermittent ground in wire between connector and sensor.

Lean Injector(s)
Perform "Injector Balance Test". See C-Charts Component Testing / Chart C-2A. Chart C-2A Injector Balance Test

Fuel Contamination
Water, even in small amounts, near the in-tank fuel pump inlet can be delivered to the injectors. The water causes a lean exhaust and can set a Code 44.

Fuel Pressure
System will be lean if pressure is too low. It may be necessary to monitor fuel pressure while driving the car at various road speeds and/or loads to confirm. See "Fuel System Diagnosis". See C-Charts Component esting / Chart A-7. Chart A-7 Fuel System Diagnosis

Exhaust Leaks
If there is an exhaust leak, the engine can cause outside air to be pulled into the exhaust and past the sensor. Vacuum or crankcase leaks can cause a lean condition.

Air System (manual transmission only)
Be sure air is not being directed to the exhaust ports while in "Closed Loop." If the block learn value goes down while squeezing air hose to exhaust ports, refer to "Electric Divert Control" Chart C-6.

If the above are OK, it is a faulty oxygen sensor.