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25 - 20 EMISSION CONTROL SYSTEMS

If both the EGR Gas Flow Check, System Check and Diagnosis Chart are completed satisfactorily, then the EGR system functions normally.

If engine speed does not drop off when performing the test, remove both the EGR valve and EGR tube and check for plugged passages. Also, check the intake manifold inlet passage. Clean or replace these components for restoration of proper flow.

EGR VALVE SERVICEÐ2.2L AND 2.5L TBI ENGINES

REMOVAL

(1)Disconnect electrical connector and vacuum line from the electric EGR transducer (Fig. 12).

(2)Remove EGR valve bolts from intake manifold.

(3)Remove EGR valve from intake manifold.

(4)Clean gasket surface and discard old gasket. Check for any signs of leakage or cracked surfaces.

INSTALLATION

(1)Assemble EGR valve with new gasket onto the intake manifold.

(2)Install EGR valve mounting bolts. Tighten to 22 NIm (200 in. lbs.) torque.

(3)Reconnect vacuum line and electrical connector to Electric EGR Transducer.

EGR TUBE SERVICEÐ2.2L AND 2.5L TBI ENGINES

REMOVAL

(1)Remove EGR tube attaching bolts from intake and exhaust manifolds.

(2)Remove EGR tube.

(3)Clean intake and exhaust manifold gasket surfaces and EGR tube flange gasket surfaces. Discard old gaskets.

(4)Check for signs of leakage or cracked surfaces on either manifolds or tube. Replace as necessary.

INSTALLATION

(1)Loosely position EGR tube and new gaskets in place on intake and exhaust manifolds. Install mounting bolts.

(2)Tighten attaching bolts to 22 NIm (200 in. lbs.) torque.

EGR SYSTEM SERVICEÐ3.0L ENGINES

REMOVAL

(1)Disconnect the electric and vacuum connectors from the electric EGR transducer (EET) (Fig. 16).

(2)Remove EGR valve nuts to exhaust manifold.

(3)Remove EGR flange bolts from valve.

(4)Remove EGR valve tube flange nuts from intake manifold.

(5)Clean all gasket surfaces and discard old gaskets. Check for any signs of leakage or cracked surfaces. Repair or replace as necessary.

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INSTALLATION

(1)Loosely assemble the EGR tube to EGR valve with new gasket in place.

(2)Install new gaskets on both intake and exhaust manifolds.

(3)Position EGR valve and tube loosely on engine.

(4)Tighten EGR tube flange nuts (on the intake manifold) to 22 NIm (200 in. lbs.) torque.

(5)Tighten EGR tube to valve screws (2) to 11 NIm (95 in. lbs.) torque.

(6)Tighten EGR valve to exhaust manifold nuts to 22 NIm (200 in. lbs.) torque.

(7)Connect the electrical and vacuum connectors to the electric EGR transducer.

EGR VALVE SERVICEÐ3.3L AND 3.8L ENGINES

REMOVAL

(1)Disconnect vacuum tube from electric EGR transducer (EET). Inspect vacuum tube for damage (Fig. 17).

(2)Remove electrical connector from EET.

(3)Remove EGR valve bolts from intake manifold.

(4)Open EGR transducer clip and remove electric EGR transducer.

(5)Remove EGR valve from intake manifold.

(6)Clean gasket surface and discard old gasket. Check for any signs of leakage or cracked surfaces. Repair or replace as necessary.

INSTALLATION

(1)Assemble EGR valve with new gasket onto the intake manifold.

(2)Install mounting bolts. Tighten bolts to 22 NIm (200 in. lbs.) torque.

(3)Install electric EGR transducer in clip with orientation tab in slot and snap closed.

(4)Reconnect vacuum hose and electrical connector to EET.

EGR TUBE SERVICEÐ3.3L AND 3.8L ENGINES

REMOVAL

(1)Remove EGR tube attaching bolts from intake and exhaust manifolds.

(2)Clean intake and exhaust manifold gasket surfaces. Discard old gasket.

(3)Check for signs of leakage or cracked surfaces on either manifolds or tube. Repair or replace as necessary.

INSTALLATION

(1)Loosely assemble EGR tube and new gaskets into place on intake and exhaust manifolds.

(2)Tighten mounting bolts to 22 NIm (200 in. lbs.) torque.

Fig. 16 EGR ServiceÐ3.0L Engines

Fig. 17 EGR SystemÐ3.3L and 3.8L Engines

AIR ASPIRATION SYSTEM

Certain vehicles equipped with the 2.2L or 2.5L TBI engines have an aspirator valve (Fig. 18). The valve uses exhaust pressure pulsation to draw fresh air from the air cleaner into the exhaust system. This

reduces carbon monoxide (CO) and hydrocarbon (HC) emissions. The aspirator valve works most efficiently at idle and slightly off-idle, where the negative pulses are strongest. The aspirator valve remains closed at higher engine speeds.

Fig. 18 Air Aspirator System

DIAGNOSIS

The aspirator valve is not repairable. Replace the valve if it operates incorrectly. Valve failure results in excessive underhood exhaust system noise at idle and hardening of the rubber hose from the valve to the air cleaner. Check for leakage at the aspirator tube/catalyst assembly joint. Also, inspect the hose connections at the aspirator valve and air cleaner for leakage. If the aspirator tube/ catalyst assembly joint is leaking, tighten the aspirator tube nut to 54 NIm (40 ft. lbs) torque. If either hose connection leaks, and the hose has not hardened, install hose clamps.

To determine if the aspirator valve has failed, disconnect the hose from the aspirator inlet. With the engine at idle in neutral, the negative (vacuum) exhaust pulses can be felt at the aspirator inlet. If hot exhaust gas is escaping from the aspirator inlet, the valve has failed. Replace the valve.

REMOVAL

(1)Disconnect the air hose from the aspirator valve

inlet.

(2)Remove aspirator tube assembly from catalyst.

INSTALLATION

(1)Install aspirator tube. Tighten the nut to 54 NIm (40 ft. lbs) torque.

(2)Install aspirator tube bracket screw. Tighten screw to 11 NIm (95 in. lbs) torque.

(3)Connect air hose to aspirator valve inlet and air cleaner nipple.