GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Pontiac 🢒 2000 🢒 Firebird 🢒 Engine 🢒 Engine Controls - 3.8L 🢒 Restricted Exhaust System Check

Step

Action

Values

Yes

No

1

Did you perform the Powertrain On-Board Diagnostic (OBD) System Check?

--

Go to Step 2

Go to Powertrain On Board Diagnostic (OBD) System Check

2
  1. Remove a pre-catalyst HO2S. Refer to Heated Oxygen Sensor Replacement .
  2. In place of the HO2S, 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 the pre-catalyst HO2S, 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 the pre-catalyst HO2S.
  2. Remove the post-catalyst HO2S.
  3. In place of the H02S, 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

Did you complete the repair?

--

Go to Step 7

--

6

Replace the three way catalytic Converter. Refer to Catalytic Converter Replacement in Engine Exhaust.

Did you complete the repair?

--

Go to Step 7

--

7
  1. Remove a pre-catalyst HO2S.
  2. In place of the HO2S, 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 the pre-catalyst HO2S, 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