Tools Required

SA9127E Gage Bar Kit

A slight pressure in the exhaust system is normal, but excessive exhaust back pressure seriously affects engine operation. Causes of high exhaust back pressure are dents/obstructions in the exhaust pipe or a plugged three way catalytic converter/muffler.

1. Remove the heated oxygen sensor.
2. Insert the exhaust back pressure adapter into the exhaust manifold. The thread designation is M18 x 1.50.
3. Connect the SA9127E gage bar kit, 0-15 kPa (0-60 in H2O) gage to back pressure adaptor.
4. With the engine at normal operating temperature, observe the exhaust back pressure at 4000 RPM.
5. The exhaust back pressure must be less than 5 kPa (20.13 in H2O).

1. Remove the heated oxygen sensor.

Notice: Do not use the 0-60 in. H2O gage when performing this test, as it will be permanently damaged due to the excessive back pressure during accelerations. Use the 0-690 kPa (0-100 psi) gage and appropriate hoses in the service gage bar kit SA9127E.

2. Install the exhaust back pressure adapter into the exhaust manifold. The thread designation is M18 x 1.50.
3. Connect the SA9127E , 0-690 kPa (0-100 psi) gage.
4. With the engine at normal operating temperature, perform a 24 km/h (15 mph) road test. Automatic transaxles should be in "D" and manual transaxles in "3rd" gear. Maximum exhaust back pressure readings are taken during short wide open throttle accelerations.

Important: If the exhaust pressure exceeds specification, inspect for a dented or collapsed exhaust pipe. It may be necessary to disconnect the exhaust pipe before or behind the converter and repeat step 4. If removing the muffler does not lower the back pressure, disconnect the three way catalytic converter from the exhaust manifold pipe and repeat the test.

5. Replace any part of the exhaust system found to be damaged.
6. Install the anti-seize on the heated oxygen sensor threads and install the sensor. It may be necessary to disconnect the negative battery terminal in order to clear any codes set while operating the engine with the heated oxygen sensor removed or disconnected.