GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Cadillac 🢒 1999 🢒 Eldorado 🢒 Engine 🢒 Engine Controls - 4.0L and 4.6L 🢒 Restricted Exhaust System Check

Restricted Exhaust System Check

Step

Action

Value(s)

Yes

No

1

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

--

Go to Step 2

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

2
  1. Remove one of the Heated O2 Sensors located before the catalytic converter.
  2. Install Exhaust Back pressure tester J 35314-A, BT 8515, BT 8603 or equivalent in place of the Heated O2 Sensor.
  3. Engine idling at normal operating temperature
  4. Observe the exhaust system back pressure reading on the gage.

Does reading exceed the specified value?

8.6 kPa (1.25 psi)

Go to Step 4

Go to Step 3

3
  1. With exhaust Back pressure tester J 35314-A, BT 8515, BT 8603 or equivalent still in place of the Heated O2 Sensor, increase engine speed to 2000 RPM.
  2. Observe the exhaust system back pressure reading on the gage.

Does reading exceed the specified value?

20.7 kPa (3 psi)

Go to Step 4

System OK

4
  1. Reinstall the Heated O2 Sensor.
  2. Remove HO2S Bnk 1 sensor 3.
  3. Install exhaust Back pressure tester J 35314-A, BT 8515, BT 8603 or equivalent in place of HO2S Bnk 1 sensor 3.
  4. Engine at normal operating temperature.
  5. Increase engine speed to 2000 RPM.
  6. Observe the exhaust system back pressure reading on the gage.

Does reading exceed the specified value?

20.7 kPa (3 psi)

Go to Step 5

Go to Step 6

5

Repair restriction in the exhaust system past the Three Way Catalytic Converter. Possible faults include the following:

    • Collapsed pipe
    • Heat distress
    • Internal muffler failure

Is the action complete?

--

Go to Step 7

--

6

Replace the Three-Way Catalytic Converter.

Is action complete?

--

Go to Step 7

--

7
  1. Remove one of the Heated O2 Sensors located before the catalytic converter.
  2. Install Exhaust Back pressure tester J 35314-A, BT 8515, BT 8603 or equivalent in place of the Heated O2 Sensor.
  3. Engine idling at normal operating temperature.
  4. Observe the exhaust system back pressure reading on the gage.

Does reading exceed the specified value?

8.6 kPa (1.25 psi)

Go to Step 4

Go to Step 8

8
  1. With exhaust back pressure tester J 35314-A, BT 8515, BT 8603 or equivalent still in place of the Heated O2 Sensor, increase engine speed to 2000 RPM.
  2. Observe the exhaust system back pressure reading on the gage.

Does reading exceed the specified value?

20.7 kPa (3 psi)

Go to Step 4

Repair complete