GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Pontiac 🢒 1999 🢒 Firebird 🢒 Engine 🢒 Engine Controls - 3.8L 🢒 Restricted Exhaust System Check

Step

Action

Value(s)

Yes

No

1

Was the Powertrain On-Board Diagnostic (OBD) System Check performed?

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Go to Step 2

Go to the Powertrain On Board Diagnostic (OBD) System Check

2
  1. Remove the HO2S Bank 1 Sensor 2. Refer to Heated Oxygen Sensor Replacement .
  2. In place of HO2S Bank 1 Sensor 2, install a J 35314-A Exhaust Back Pressure Tester.
  3. Start the engine.
  4. With the transmission in Park or Neutral and the engine idling at normal operating temperature, observe the exhaust system back pressure reading on the gage.

Does the reading exceed the specified value?

8.6 kPa (1.25 psi)

Go to Step 4

Go to Step 3

3
  1. Leave the transmission in Park or Neutral.
  2. With the exhaust back pressure tester in place of HO2S Bank 1 Sensor 2, increase engine speed to 2000 rpm.
  3. Observe the exhaust system back pressure reading on the gage.

Does the reading exceed the specified value?

20.7 kPa (3 psi)

Go to Step 4

System OK

4
  1. Reinstall HO2S Bank 1 Sensor 2.
  2. Remove HO2S Bank 1 Sensor 3.
  3. In place of H02S Bank 1 Sensor 3, install J 35314-A Exhaust Back Pressure Tester.
  4. Engine at normal operating temperature.
  5. Leave the transmission in Park or Neutral.
  6. Increase engine speed to 2000 rpm.
  7. Observe the exhaust system back pressure reading on the gage.

Does the reading exceed the specified value?

20.7 kPa (3 psi)

Go to Step 5

Go to Step 6

5

Locate and repair the restriction in the exhaust system past the three way catalytic converter. Possible faults include the following:

    • Collapsed pipe.
    • Heat distress.
    • Internal muffler failure.

Is action complete?

--

Go to Step 7

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6

Replace the three way catalytic Converter.

Is action complete?

--

Go to Step 7

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7
  1. Remove HO2S Bank 1 Sensor 2.
  2. In place of HO2S Bank 1 Sensor 2, install J 35314-A Exhaust Back Pressure Tester.
  3. Leave the transmission in Park or Neutral.
  4. Engine idling at normal operating temperature.
  5. Observe the exhaust system back pressure reading on the gage.

Does the reading exceed the specified value?

8.6 kPa (1.25 psi)

Go to Step 4

Go to Step 8

8
  1. Leave the transmission in Park or Neutral.
  2. With exhaust each pressure tester in place of HO2S Bank 1 Sensor 2, increase engine speed to 2000 rpm.
  3. Observe the exhaust system back pressure reading on the gage.

Does the reading exceed the specified value?

20.7 kPa (3 psi)

Go to Step 5

System OK