Intake Manifold: Service and Repair

Fig.15 Lower intake manifold bolt tightening sequence. 4-140 engine:

Fig. 16 Upper intake manifold bolt tightening sequence. 4-140 engine:

4-140 Engine

1. Disconnect battery ground cable.
2. Disconnect the following electrical connectors:
a. Throttle Position Sensor (TPS).
b. Injector wiring harness.
c. Knock sensor.
d. Air charge temperature sensor.
e. Engine coolant temperature sensor.
3. Disconnect vacuum lines at upper intake manifold vacuum tree. Label vacuum hose locations using suitable tape to facilitate installation.
4. Disconnect vacuum line from EGR valve and fuel pressure regulator.
5. Remove throttle linkage shield, then disconnect throttle linkage, cruise control and kickdown cable.
6. Remove accelerator cable from bracket and position to one side.
7. Disconnect air intake hose, air bypass hose and crankcase vent hose.
8. Disconnect PCV system hose from fitting on underside of upper intake manifold.
9. Disconnect lower intake manifold water bypass line, then the EGR tube from EGR valve.
10. Remove upper intake manifold retaining nuts, then the manifold and throttle body as an assembly.
11. Disconnect manifold fuel supply and fuel return lines.
12. Remove engine oil dipstick bracket attaching bolt.
13. Disconnect fuel injector electrical connectors and position harness to one side.
14. Remove two fuel supply manifold attaching bolts, then the fuel supply manifold and injectors.
15. Remove lower manifold attaching bolts, then the lower manifold.
16. Reverse procedure to install, noting the following:
a. Torque lower intake manifold attaching bolts to 12 - 15 ft. lbs. in the sequence shown in Fig. 15.
b. Torque fuel injector manifold to fuel charging assembly attaching bolts to 15 - 22 ft. lbs.
c. Torque fuel pressure regulator attaching bolts to 27 - 40 inch lbs.
d. Torque upper intake manifold attaching bolts to 14 - 21 ft. lbs. in the sequence shown in Fig. 16.
e. Torque air throttle body attaching bolts to 12 - 15 ft. lbs.
f. Replace fuel pressure cap, then without starting the engine build up fuel pressure by turning key back and forth at least six times from ``ON'' to ``OFF'' position, leaving key on for 15 seconds each time.