JFROG

Really need some help here. have a 93 pontiac transport (same as lumina). has 3.1L v6 with tbi same as on v-8 except injectors are different. only code pulled is 44. stalls, surges, and no throttle response. although after driving it for about 30 mins. it will run better (still some surging and hesitation). I always thought bad fuel pumps would do the opposite. (run good then worse when warmed up). replaced ignition module. plugs, wires,cap, rotor, and o2 sensor about 2 months ago. like i said no other codes than 44. which usually is the fuel pump but wanted to get another opinion before i drop the tank. (going to do myself, not wanting to drop too much money into van as will try to get newer vehicle in the spring)

snflupigus

i think the fuel pumps warm up and "loosen up" or something and work better after that. Just replaced a fuel pump in a car doing the same thing... stalls, surge, had to feather the gas like crazy just to get it to run. #1 tell tale sign was the injector spray cone was WEAK at opening of the throttle. Spray some carb cleaner in the intake while idling and running and see if it starts to run normally. if so, you've got a fuel problem. and probably the pump.

here is a quote from GM ECM Code 44

This is the description of a Code 44 as set on GM products It is an indication of a lean mixture as indicated by the oxygen sensor readings.

Circuit description: The ECM supplies a voltage of about .45 volts between the appropriate terminals of the sensor. (If measured with a ten megohm DVM, this may read as low as .32 volt). The O2 sensor varies the voltage within a range of about one volt, if the exhaust is rich, down thru about .10 volt, if exhaust is lean.

The sensor is like an open circuit and produces no voltage, when it is below about 360 degrees C, 600 degreeF. An open sensor circuit, or a cold sensor, causes Open Loop operation.

Test description:

1.) Code 44 is set when the O2 sensor signal voltage remains below .3 volts for 50 seconds or more and the system is operating in "closed loop".

Diagnostic aides:

The code 44 for lean exhaust is most likely caused by one or more of the following:

1.) O2 sensor wire - Sensor pigtail may be mispositioned and contacting the exhaust manifold.

2.) Check for an intermittent ground wire between connector and sensor.

3.) Poor ECM to engine block ground.

4.) MAF Sensor - A MAF sensor that causes the ECM to sense a lower than normal airflow will cause the system to go lean. Disconnect the MAF sensor. If the lean condition is gone then replace the MAF sensor.

5.) Vacuum leaks can cause a lean condition and/or possibly a high idle. Check for cracked hoses a bad gasket or a faulty EGR or PCV Valve.

6.) fuel pressure - system will go 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.

7.) Clogged injector or lean injector - perform an injector balance test..

Bobby_80s

iTrader: (2)

where are the proper ground for the ecm and o2 sensor?