No intake vacuum Honda VF750 Magna Sabre

High idle is most often caused by an engine vacuum leak, use a can of carburetor spray and spray it around the intake manifolds (upper and lower), if there is a leak you will hear a change in the idle speed

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Yes there are cooling system hoses under the intake, here are instructions to remove the intake.

Instructions

1. Remove the Intake Manifold
   • 1Drain the cooling system and relieve the pressure in the fuel system. Disconnect the negative battery cable, the air intake duct, the IAC valve connectors, the throttle position sensor and switch connectors, and the EGR solenoid valve.
     
   • 2Pull the EVAP canister vacuum and purge hoses, the vacuum hoses from the EVAP, the brake cylinder, pressure regulator and EGR tube. Tag and disconnect the spark plug wires. Remove the distributor cap.
     
   • 3. Take out the three left bank injector connectors, the thermal transmitter, the ground harness, breather pipe and the upper manifold. Disconnect the fuel feed and return lines and plug them with golf tees to prevent fuel spillage.
     
   • 4Locate the right injector harness connectors and disconnect them as well as the fuel rail and injectors. Remove the coolant temperature switch harness connector and the water hose from the thermostat.
     
   • 5Loose the bolts on the lower manifold in sequence. Remove the bolts and left the intake manifold from the engine. Remove the gasket and discard it.
     
   • 6Clean the mating surfaces by scraping the old gasket material and carbon deposits. Clean the surfaces with solvent and inspect them for damage.
     
   Install the Intake Manifold
   • 7Put a new gasket in place and install the lower intake manifold to the engine. Tighten the bolts in sequence as follows: first pass-35 inch pounds; second pass-78 inch pounds and third pass 70 to 84 inch pounds.
     
   • 8Connect the ECT sensor connector, the fuel supply manifold and the right bank injector connectors. Connect the fuel lines and then install the upper intake manifold. Put the breather pipe in position.
     
   • 9Install the intake manifold ground cable, the thermal transmitter, the left bank injector connectors and the distributor. Reconnect the spark plug wires.
     
   • 10Continue reconnecting all the components, reversing the order in which they were removed. Connect the negative battery cable to the terminal. Refill the cooling system with the appropriate coolant.
     
   • 11Start the engine. Check for fuel or vacuum leaks.
     

P0171 fuel lean bank 1, P0 174 Fuel lean bank 2 More likely the MAF you can correct this by cleaning the MAF but you need to use brake cleaner and you ahve to remove it from its housing (it has anti tampering screws) a vacuum leak can also cause both banks to go lean and even low fuel pressure wheter it is a filter or pump

Yes you do, the following info explains the necessary procedure.



Click here to enlarge image.

Click here to enlarge image.

1. Properly relieve the fuel system pressure.
2. Disconnect the negative battery cable. Place a clean drain pan under the radiator, open the drain **** and drain the cooling system.
3. Remove the air cleaner assembly and the fuel injector sight shield.
4. Disconnect the cables from the throttle body and mount bracket.
5. Remove the coolant recovery reservoir.
6. Remove the inner fender electrical cover on the right side.
7. Remove the right rear crossover pipe heat shield.
8. Disconnect the fuel lines from the fuel rail and from the cable bracket.
9. Remove the alternator and brace.
10. Remove the throttle body cable mounting bracket with the vacuum lines and disconnect the vacuum lines.
11. Tag and detach the electrical connections at the throttle body and both banks of fuel injectors.
12. Disconnect the vacuum hoses from the canister purge solenoid valve and transaxle module and intake connection.
13. Unbolt the power steering pump and move forward. DO NOT disconnect the fluid lines.
14. Tag and disconnect the spark plug wires position lay aside.
15. Disconnect the coolant bypass hose from the intake manifold.
16. Remove the solenoid valve mounting bracket and power steering support brace from the intake manifold.
17. Disconnect the heater pipes from the intake and front cover.
18. Remove the alternator support brace from the intake.
19. Disconnect the upper radiator hose from the housing.
20. Remove the thermostat housing and thermostat from the intake.
21. Detach the electrical connector from the temperature sensor and sensor switch.
22. Unfasten the intake manifold bolts, then remove the manifold as an assembly. Remove and discard the gaskets.
23. If separating the upper manifold from the lower, proceed as follows:
24. Remove the fuel rail and fuel injectors.
25. Detach the coolant sensor switch.
26. Remove the manifold end cap cover.
27. Remove the upper intake manifold and throttle body assembly from the lower manifold. Remove and discard the gaskets. To install:
    
28. Thoroughly clean all gasket mating surfaces.
29. If replacing the upper manifold, proceed as follows:
30. Apply a 1⁄16 in. bead of Loctite® Instant Gasket Eliminator 51845 or equivalent to the lower manifold mating surface. Make sure to circle all bolt holes.
31. Carefully lower the upper manifold and throttle body assembly onto the lower manifold.
32. Tighten the upper manifold retaining bolts to 19 ft. lbs. (26 Nm).
33. Install the manifold end cap cover and the coolant sensor switch.
34. Install the fuel injectors and rail to the manifold assembly.
35. Clean the mating surfaces and install the intake manifold gaskets and seals. Apply sealer to the ends of the of the intake manifold seals.
36. Position the intake manifold and apply a suitable thread lock compound to the bolt threads. Tighten the retaining bolts to 88 inch lbs. (10 Nm), twice, in the sequence shown in the accompanying figure.
37. Attach the electrical connector to the temperature sensor and sensor switch.
38. Install the thermostat housing and thermostat with a new gasket.
39. Connect the alternator support brace to the intake.
40. Install the solenoid valve mounting bracket and power steering support brace to the intake manifold.
41. Connect the heater pipes to the intake and front cover.
42. Attach the coolant bypass hose to the intake manifold.
43. Install the power steering pump support bracket and tighten to 37 ft. lbs. (50 Nm).
44. Install the spark plug wires on both sides.
45. Install the belt tensioner pulley and tighten to 33 ft. lbs. (45 Nm).
46. Install the power steering pump.
47. Connect the vacuum hoses to the canister purge solenoid valve and transaxle module and intake connection.
48. Attach the electrical connections at the throttle body and both banks of fuel injectors.
49. Install the alternator and brace.
50. Connect the throttle body cable mounting bracket with the vacuum lines.
51. Install the right rear crossover pipe heat shield.
52. Install the cables to the throttle body.
53. Connect the fuel lines to the fuel rail and mount bracket.
54. Install the inner fender electrical cover on the right side.
55. Install the coolant recovery reservoir and upper radiator hose. Fill the cooling system.
56. Install the air cleaner assembly and the fuel injector sight shield.
57. Connect the negative battery cable.

3.8L Engine (most common) Upper Intake Manifold To Remove:

1. Drain the cooling system.
2. Remove or disconnect the following:
   • Negative battery cable.
   • Fuel injector sight shield.
   • Air cleaner intake duct.
   • Right spark plug wires from the ignition control module and reposition.
3. Relieve the fuel pressure.
4. Remove or disconnect the following:
   • Fuel rail assembly.
   • Brake booster hose from the vacuum source manifold in the upper intake manifold.
   • Exhaust Gas Recirculation Valve (EGR) wiring harness heat shield nut, bolt and the EGR heat shield.
   • Throttle body support bracket upper bolt.
5. Disconnect the electrical connectors from the following:
   • EVAP purge solenoid
   • Throttle Position (T/P) sensor
   • Idle Air Control (IAC) valve
   • Manifold Absolute Pressure (MAP) sensor
   • Mass Air Flow (MAF) sensor
   • EVAP purge solenoid vacuum line from the throttle body.
   • Accelerator and the cruise control cables with the bracket from the throttle body.
6. Remove or disconnect the following:
   • Upper intake manifold bolts and stud.
   • Clean the upper intake manifold bolt threads.
7. Remove or disconnect the following:
   • Upper intake manifold by lifting the back of the intake and sliding the manifold forward from the throttle body support bracket.
   • Upper-to-lower intake manifold carrier gasket from the upper intake manifold.
8. If the upper intake manifold is being replaced, remove the following:
   • Throttle body assembly.
   • Manifold Absolute Pressure (MAP) sensor.
   • Positive Crankcase Ventilation (PCV) valve.
   • Vacuum source manifold.

Upper intake manifold bolt torque sequence (3.8L engine)

To Install:

1. If the manifold was replaced, install or connect the following:
   • Vacuum source manifold.
   • Positive Crankcase Ventilation (PCV) valve.
   • Manifold Absolute Pressure (MAP) sensor.
   • Throttle body assembly.
   • Upper-to-lower intake manifold carrier gasket to the upper intake manifold.
2. Carefully place the upper intake manifold onto the lower intake manifold. Ensure that the alignment pins in the upper intake manifold align with the holes in the lower intake manifold. NOTE: Apply thread lock compound, to the bolt threads before assembly.
   
3. Install or connect the following:
   • Upper intake manifold. Tighten the upper intake manifold bolts in sequence to 89 in lbs (10 Nm)
   • Accelerator and the cruise control cables with the bracket to the throttle body.
   • EVAP purge solenoid vacuum line to the throttle body.
4. Connect the electrical connectors to the following:
   • Mass Air Flow (MAF) sensor
   • Manifold Absolute Pressure (MAP) sensor
   • Idle Air Control (IAC) valve
   • Throttle Position (T/P) sensor
   • EVAP purge solenoid
5. Install or connect the following:
   • Throttle body upper support bracket bolt. Tighten the bolt to 89 in lbs (10 Nm)
   • EGR valve wiring harness heat shield, nut and the bolt. Tighten the nut and the bolt to 89 in lbs (10 Nm)
   • Brake booster hose to the vacuum source manifold.
   • Fuel rail assembly.
   • Right spark plug wires.
   • Air cleaner intake duct.
   • Fuel injector sight shield.
6. Connect the negative battery cable.
7. Fill the cooling system.
8. Inspect for fluid or vacuum leaks.

Lower Intake Manifold (W/O Supercharger) To Remove:

1. Remove or disconnect the following:
   • Upper intake manifold.
   • Generator brace.
   • Drive belt tensioner with the mounting bracket and the heater water bypass inlet pipe.
   • Exhaust gas recirculation EGR outlet pipe bolt from the lower intake manifold.
   • Radiator inlet hose from the water outlet housing.
   • ECT sensor electrical connector.
   • Right upper engine mount strut bracket.
   • Generator brace bracket bolts.
   • Generator brace bracket.
   • Lower intake manifold bolts.
   • Lower intake manifold.
   • Lower intake manifold seals.
   • Lower intake manifold gaskets.
2. If replacing the lower intake manifold, Remove or disconnect:
   • Water outlet housing bolt and stud
   • Water outlet housing
   • Gasket and the thermostat.
   • ECT sensor.
3. Inspect the flatness of inlet flanges.
4. Clean the intake manifold mating surfaces.
5. Clean the intake manifold bolts and bolt holes of adhesive compound.

To Install:

1. If removed, install the ECT sensor.
   • Tighten the ECT sensor to 18 ft. lbs. (25 Nm)
2. If removed, install the thermostat, the gasket, and the water outlet housing.
3. If removed, install the water outlet housing bolt and the stud.
   • Tighten the bolt and stud to 20 ft. lbs. (27 Nm)
4. Install or connect the following:
   • Lower intake manifold gaskets. NOTE: Apply sealer GM P/N 12346286 (Canadian P/N 10953472) or equivalent to the ends of the intake manifold seals.
     
   • Lower intake manifold seals.
   • Lower intake manifold.
   • Lower intake manifold bolts.
   NOTE: Apply thread lock compound GM P/N 12345382 (Canadian P/N 10953489) or equivalent to the two hidden bolts and ensure they are installed.
   
5. Tighten the lower intake manifold bolts in sequence to 11 ft. lbs. (15 Nm)
   
   
6. Install or connect the following:
   • Generator brace bracket.
   • Generator brace bracket bolts. Tighten the bolts to 37 ft. lbs. (50 Nm)
   • Right upper engine mount strut bracket.
   • ECT sensor electrical connector.
   • Radiator inlet hose to the water outlet housing.
   • EGR outlet pipe to the lower intake manifold.
   • EGR outlet pipe bolt to the lower intake manifold. Tighten the bolt to 21 ft. lbs. (29 Nm)
   • Drive belt tensioner.
   • Generator brace.
   • Upper intake manifold.
7. Inspect for leaks.

Lower Intake Manifold (W/ Supercharger) To Remove:

1. Disconnect the negative battery cable.
2. Drain the cooling system.
3. Remove the supercharger.
4. Remove the thermostat housing.
5. Remove the EGR pipe at the intake manifold.
6. Disconnect the electrical connection at the temperature sensor.
7. Remove the intake manifold and gaskets.

NOTE: The coolant bypass tube will release from the intake manifold when the manifold is removed.
To Install:

1. Clean the gasket sealing surfaces.
2. Install the intake manifold gaskets.
3. Align the coolant bypass tube with the opening in the intake manifold and install the manifold. Tighten the bolts to 11 lb ft (15 Nm).
4. Install the electrical connector to the temperature sensor.
5. Install the EGR pipe to the intake manifold.
6. Install the thermostat housing.
7. Install the supercharger.
8. Fill the cooling system.
9. Connect the negative battery cable.

Check the rpm gauge while running. If the RPM needle fluxuates while idling that is caused by a defective spark plug and or a spark plug wire

Two bad O2 sensors is rare. The problem is before the sensor,intake vacuum leak, injector lower o-ring, IMCR stuck open or the control rod is off, vacuum hose(s) off, or MAF sensor. If this has a plastic upper intake, they had problems with o-rings.

Have u checked for vacuum leaks or poss leaking EGR valve? use carb spray around the upper intake manifold where it bolts to the lower manifold, spray vacuum lines where they are connected to the engine vacuum ports, the idle speed will change if u hit a leak, as far as the EGR valve goes see if it gets hot at idle, if it does it is leaking, if all checks ok replace the O2 sensor, but i suspect u will find a leak at the upper intake plenum.

Removal (3000GT AWD)
1. Remove air cleaner cover, air hoses and vacuum pipe. Remove air cleaner, intake hose, battery, battery
tray and washer tank.
2. Disconnect transaxle control cables and speedometer cable. Raise and support vehicle.
3. Remove both inner fender splash shields. Remove clutch tube bracket and disconnect clutch release
cylinder (including clutch damper assembly on FWD models) and wire aside. Support transaxle assembly
with jack and disconnect upper transaxle mount. Remove mount, bracket, plug and stoppers.
4. Remove transaxle assembly upper coupling bolts. Disconnect tie rod ends and lower arm ball joints.
Remove right support member, starter cover (if equipped) and starter.
5. Remove left side bearing bracket mounting bolts and pry left axle shaft from transaxle. Wire left axle
shaft and inner shaft assembly aside. Pry right axle shaft from transaxle and wire aside.
6. Remove front bank side and rear bank side transaxle stays. Support transaxle assembly with a
transmission jack. Remove transaxle assembly lower coupling bolts and lower transaxle from vehicle.
7. Insert a clutch alining tool to prevent pressure plate and clutch disc from falling. Loosen pressure plate
bolts gradually in a crisscross pattern to avoid warping pressure plate flange. Remove pressure plate and
clutch disc.