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BuickR ... 4/22/2010

1998 Buick Regal LS 6 Cyl 3.8L


Fuel too lean bank 1 after manifold replacement

I just had my intake manifold and valve gaskets replaced. I am getting engine code p0171 which is fuel system too lean in bank 1. The mechanic can't find a leak around the intake manifold, he used starter fluid to check.

2 Answers


Blackwater 8/18/2010

These are the things you have to check

PCM software needs to be updated
Vacuum leaks (Intake Manifold Gaskets, vacuum hoses, PCV hoses, etc.)
Mass Airflow Sensor (MAF)
Plugged Fuel Filter or weak Fuel Pump
Plugged or dirty Fuel Injectors


HouseCallAuto 8/18/2010

1. Run water over the top of the engine, checking for RPM response.

2. Check for intake vacuum leaks if RPM changes.

3. If OK, check the Positive Crankcase Ventilation (PCV) valve and o-ring for a leak.

4. Remove the Manifold Absolute Pressure (MAP) sensor and the PCV valve.

5. Block the intake manifold cavity with a rag.

6. Connect a vacuum gauge to the dipstick tube.

7. Check for crankcase vacuum with the engine running.

8. Replace the lower intake manifold gaskets if vacuum is detected in the crankcase.

9. Clean the Mass Air Flow (MAF) sensor elements with a Q-tip and contact cleaner.


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