Intake Manifold: Service and Repair

Fig. 3 Intake Manifold Removal & Installation:

1. On applicable models, disable airbag system as described under MAINTENANCE PROCEDURES/AIRBAG SYSTEM DISARMING.
2. Relieve fuel system as pressure as follows:
a. Loosen gas cap to release tank pressure.
b. Disconnect electrical connector from injector.
c. Ground one injector terminal using a jumper wire.
d. Connect jumper wire to second terminal and touch battery positive terminal for no longer than 10 seconds, then remove jumper wire.
3. Disconnect battery ground cable.
4. On 1990 Sigma models, tape and isolate battery ground cable terminal. Wait at least 30 seconds before proceeding.
5. On all models, drain cooling system.
6. Remove air cleaner to throttle body hose, then disconnect throttle cable and transaxle kickdown linkage, if equipped, Fig. 3.
7. Disconnect automatic idle speed (AIS) motor and throttle position sensor (TPS) electrical connectors from throttle body.
8. Disconnect vacuum hoses from throttle body.
9. Remove EGR tube flange from intake plenum.
10. Disconnect coolant temperature sensor and charge temperature sensor electrical connectors.
11. Disconnect air intake plenum vacuum connector, then disconnect fuel hoses from fuel rail.
12. Remove air intake plenum to intake manifold attaching bolts, then the air intake plenum.
13. Disconnect vacuum hoses from fuel rail and fuel pressure regulator, then disconnect fuel injector electrical connector from engine wiring harness.
14. Remove fuel pressure regulator attaching bolts, then loosen hose clamps and remove regulator from rail.
15. Remove fuel rail attaching bolts, then lift fuel rail assembly from intake manifold.
16. Disconnect radiator hose from thermostat housing and heater hose from heater pipe.
17. Remove intake manifold attaching bolts, then the intake manifold.
18. Reverse procedure to install, noting the following:
a. Discard gaskets and clean gasket surfaces on both manifolds and cylinder head.
b. Use a straightedge to ensure gasket surfaces on manifolds are flat and within .004-.008 inch per foot of manifold length.
c. Tighten intake manifold bolts to specifications.
d. Tighten fuel rail attaching bolts to specifications.
e. Tighten air intake plenum attaching bolts to specifications.
f. Tighten EGR tube flange nut to specifications.
g. On 1990 Sigma models, ensure no one is inside of vehicle, then rearm airbag system as described under MAINTENANCE PROCEDURES/AIRBAG SYSTEM DISARMING.