Engine Exhaust System: Overview Pontiac Sunfire I

Test Description

The numbers below refer to the step numbers on the diagnostic table.

1. 4. The exhaust system has very low back pressure under normal conditions. If the exhaust system is restricted, a significant increase in the exhaust pressure is noticed on the J 35314-A. Removing the HO2S sensor may set a DTC. When finishing this diagnostic table, be sure to clear all codes.
2. 5. This step will isolate the catalytic converter from the remainder of the exhaust system.
3. 8. Confirming that the condition has been fixed is essential. If the symptom still exists and the vehicle has a dual exhaust system, proceed to Step 2 and repeat diagnostic procedure on the opposite exhaust pipe.

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Scheme 8

1. Disconnect the negative battery cable.
2. Remove the exhaust manifold heat shield.
3. Remove the oxygen sensor. Refer to «OXYGEN SENSORS»(ref-153402-S05886394342003040400000) .
4. Raise and support the vehicle. Refer to Lifting and Jacking the Vehicle in General Information. NOTE: Do not bend the exhaust flex decoupler more than 3 degrees in any direction. Movement of more than 3 degrees will damage the exhaust flex decoupler.
5. Remove the pipe to manifold nuts (3).
6. Pull down and back on the exhaust pipe in order to disengage the pipe from the exhaust manifold.
7. Lower the vehicle.
8. Remove the exhaust manifold to cylinder head nuts.
9. Remove the exhaust manifold.
10. Clean all the sealing surfaces.

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1. Install a new exhaust manifold gasket.
2. Install the exhaust manifold to the cylinder head. (Scheme 8) Important: Install the new exhaust nuts.
3. Install the new exhaust manifold to cylinder head retaining nuts. Follow the tightening sequence. Tighten Tighten the nuts to 13 N.m (115 lb in).
4. Raise and support the vehicle. Refer to Lifting and Jacking the Vehicle in General Information.
5. Install a new exhaust manifold to flex coupler gasket (2).
6. Push the flex coupler into position on the exhaust manifold. Important: Install the new exhaust nuts.
7. Install the retaining nuts (3) which secure the manifold to the flex decoupler (4). Tighten Tighten the nut to 30 N.m (22 lb ft).
8. Lower the vehicle.
9. Install the oxygen sensor. Refer to «OXYGEN SENSORS»(ref-153402-S05886394342003040400000).
10. Install the exhaust manifold heat shield. Tighten Tighten the bolts to 25 N.m (18 ft lbs).
11. Connect the negative battery cable.

Exhaust System Description

Important: Use of non-OEM parts may cause driveability concerns.

The exhaust system carries exhaust gases, treated by the catalytic converter, through a resonator, if applicable and into the exhaust muffler where exhaust noise is lessened.

In order to secure the exhaust pipe to the exhaust manifold, a flange and seal-joint coupling is utilized. The exhaust system may utilize a slip-joint coupling design with a clamp and a U-bolt or a flange connection with a gasket.

Exhaust hangers and rubber insulators help to support the weight of the exhaust pipe along with insulating any exhaust system vibration, rattle, or noise.

Exhaust hangers also space the exhaust system away from the underbody of the vehicle and allows the exhaust system to expand as the exhaust system warms up.

Exhaust heat shields are used to protect the body and other components from damage due to the heat from the exhaust system.

The exhaust system may be comprised of the following components

1. Exhaust manifold
2. Exhaust pipes
3. Catalytic converters
4. Exhaust muffler
5. Exhaust resonator, if equipped
6. Exhaust tail pipe, if equipped
7. Exhaust hangers
8. Exhaust heat shields