Low fuel milage and black exhaust smoke

[SESH1]

Hi I have a 1996 Corsica with a 3.1 SFI. I is getting ralley bad gas milage. The ODC II code reader says P 0101 and 0171. It gets about 10 miles to the gallon. When I mash the gas, black smoke pours out I changed the MAP sensor and also the fuel pressure regulator. But it's still doing the same thing. I pulled the plugs and they're all black with soot. But not foulded.

Does anyone have any suggestions that I might try to correct this problem ?


Mike

[GMMerlin]

p0101 is a Mass Air Flow sensor performance code and the p0171 is a fuel trim lean code.
You will need to diagnos the codes to find your problem.
What ever is causing the 101 code is the problem...the 171 code is a result of whats going on...fix the 101 and the 171 should clear.


Here is the diadnostic chart.
Important: Do not clear DTCs!

Disconnect MAF sensor connector.
Attempt to start engine.
Does engine start and continue to run?
--
Go to Step 5
Go to Step 6

5
Ignition Off reconnect MAF sensor.
Start engine observe MAP sensor display on the scan tool while slowly increasing engine speed to 3000 RPM.
Does the MAP sensor value change as engine speed increases?
--
Go to Step 7
Go to Step 6

6
Refer to DTC P0106 to diagnose MAP sensor circuit.

Is action complete?
--
Go to Step 20
--

7
Turn OFF the ignition for 30 seconds.
Turn ON the ignition with the engine OFF.
Observe the TP sensor parameter with a scan tool.
Depress the accelerator pedal completely.
Is the TP sensor parameter within the specified range?
0-100 %
Go to Step 8
Go to DTC P0121


8
Ignition OFF.
Disconnect the MAF sensor connector.
Ignition ON, engine OFF.
Using a DVM, measure voltage between the MAF signal circuit and chassis ground.
Is the voltage near the specified value?
5V
Go to Step 9
Go to Step 10

9
Connect a test light between the MAF sensor ignition feed and ground circuits at the MAF sensor harness connector.

Is the test light ON?
--
Go to Step 13
Go to Step 12

10
Is the voltage less than the specified value?
4.5V
Go to Step 14
Go to Step 11

11
Ignition OFF, disconnect the PCM.
Ignition ON, engine OFF.
Measure voltage between the MAF signal circuit and ground.
Does the voltage measure near the specified value?
0V
Go to Step 20
Go to Step 17

12
Connect a test light between MAF sensor ignition feed circuit and chassis ground.

Is the test light ON?
--
Go to Step 15
Go to Step 16

13
Check for a poor connection at the MAF sensor.
If a poor connection is found, replace faulty terminal(s) (refer to Repair Procedures in Electrical Diagnosis section 8A-5).
Was a poor connection found?
--
Go to Step 20
Go to Step 18

14
Check the MAF signal circuit for the following conditions:

Excessive resistance between the PCM and the MAF sensor
Excessive resistance in ground circuit
Shorted to the MAF sensor ground circuit
Poor connection at the PCM.
If a problem is found, repair as necessary (refer to Repair Procedures in Electrical Diagnosis section 8A-5).
Was a problem found?
--
Go to Step 20
Go to Step 19

15
Locate and repair the open in the ground circuit to the MAF sensor (refer to Repair Procedures in Electrical Diagnosis section 8A-5).

Is action complete?
--
Go to Step 20
--

16
Locate and repair the open, or excessive resistance in the ignition feed circuit to the MAF sensor (refer to Repair Procedures in Electrical Diagnosis section 8A-5).

Is action complete?
--
Go to Step 20
--

17
Locate and repair the short to voltage in the MAF signal circuit (refer to Repair Procedures in Electrical Diagnosis section 8A-5).

Is action complete?
--
Go to Step 20
--

18
Replace the MAF sensor.

Is action complete?
--
Go to Step 20
--

19
Replace the PCM.

Important: Replacement PCM must be programmed. Refer to On-Vehicle Service in Powertrain Control Module and Sensors for procedures.

Is action complete?
--
Go to Step 20
--

20
Ignition ON, engine OFF, review and record scan tool Fail Records data.
Clear DTCs.
Operate vehicle within Fail Records conditions as noted.
Using a scan tool, monitor SPECIFIC DTC info for DTC P0101.
Does scan tool indicate DTC P0101 failed this ignition?
--
Go to St

[SESH1]

I appriciate the help. I finally replaced the o2 sensor and that fixed the problem. No more fault codes for now.

Thanks for the help.

Mike S