Honda Civic Service Manual: Intake Manifold Removal and Installation (R18A9)

This procedure should be done outside in a well-ventilated area or in a properly equipped CNG shop.

This procedure will allow you to safely work on any part of the fuel system downstream of the manual shut-off valve, such as fuel pressure regulator P1 or the fuel injectors.

1.

Close the manual shut-off valve (A).

2.

Start the engine, and let it idle.

3.

After a few minutes, the engine will stall.

4.

Turn the ignition switch to LOCK (0).

NOTE: Set the wiper arms to the auto-stop position before removal.

1.

Remove the cowl top wiper covers (A).

2.

Remove the wiper arms (B).

1.

Remove the side cowl cover (A).

2.

The left side is shown; repeat on the right side.

1.

Remove the center cowl cover (A).

2.

Disconnect the windshield washer tube (B).

3.

If necessary, remove the hood rear seal (C).

1.

Remove the under cowl panel (A).

1.

Disconnect the fuel feed hose.

1.

Make sure the ignition switch is in LOCK (0).

2.

Disconnect and isolate the negative cable and battery sensor (A) from the battery.

NOTE: Always disconnect the negative side first.

3.

Disconnect the positive cable (B) from the battery.

1.

Disconnect the intake air duct (A).

2.

Remove the air cleaner (B).

3.

Remove the harness clamp (C).

1.

Remove the intake air duct.

1.

Remove the throttle body without disconnecting the hoses.

1.

Disconnect the EVAP canister hose (A), the brake booster vacuum hose (B), and the PCV hose (C).

2.

Remove the heater hose clamp bracket.

3.

Remove the intake manifold bracket.

4.

Disconnect the connectors (A).

5.

Remove the harness clamps.

6.

Remove the intake manifold assembly.

1.

Install the intake manifold assembly (A) with new gaskets (B).

2.

Tighten the bolts/nuts in a crisscross pattern in three steps, beginning with the inner bolt.

3.

Install the connectors (A).

4.

Connect the harness clamps.

5.

Install the intake manifold bracket.

6.

Install the heater hose clamp bracket.

7.

Connect the EVAP canister hose (A), the brake booster vacuum hose (B), and the PCV hose (C).

1.

Install the throttle body (A) with new gasket (B).

1.

Install the intake air duct.

1.

Install the harness clamp (A).

2.

Install the air cleaner (B).

3.

Connect the intake air duct (C).

1.

Connect the fuel feed hose (A) with a new O-ring (B).

1.

Open the manual shut-off valve (A).

Check for a gas leak if there is an odor coming from the vehicle. Compressed natural gas (CNG) can only be smelled, not seen.

1.

Open the hood and the fuel fill door.

2.

Connect a vacuum pump/gauge, 0－30 inHg, to the hose (A) from fuel pressure regulator P1, and apply 67.7 kPa (20.0 inHg, 508 mmHg) of vacuum.

3.

If fuel pressure regulator P2 does not hold vacuum, replace it before continuing to the next step.

4.

Inspect the fuel lines and hoses under the hood for kinks, abrasion, and other signs of damage.

5.

With the manual shut-off valve open, turn the ignition switch to ON (II), but do not start the engine.

6.

After the fuel pressure regulator shut-off solenoid valve/fuel tank internal solenoid valve operates for about 2 seconds, the fuel pressure in the fuel lines rises.

7.

Turn the ignition switch to LOCK (0).

8.

Repeat this two or three times.

9.

Within 1 minute, check for any damaged lines with a leak detector (A) (Snap-on Combustible Gas Leak Detector or Snoop Liquid Leak Detector (B)).

10.

If no damage was noticed during the inspection, turn the ignition switch to ON (II) for 2 seconds, then turn the ignition switch to LOCK (0).

11.

Within 1 minute, check for a leak at the vent hose outlet inside the fuel pipe protector (A).

12.

If you detect a leak, remove the vent hose, and check the fuel lines and fittings at the in-tank solenoid valve and the join block with a leak detector.

13.

If you cannot find the leak, raise the vehicle on a lift, remove the under-floor cover.

14.

Inspect all the fuel lines under the vehicle, visually, and with a leak detector.

15.

If you still cannot find the leak, remove the rear seat, then check all fuel lines and fittings at the fuel tank and the fuel joint block.

1.

Install the under cowl panel (A).

1.

If necessary, install the hood rear seal (A).

2.

Connect the windshield washer tube (B).

3.

Install the center cowl cover (C).

1.

Install the side cowl cover (A).

2.

The left side is shown; repeat on the right side.

NOTE: Set the wiper arms to the auto-stop position before installation.

1.

Install the wiper arms (A).

2.

Install the cowl top wiper covers (B).

NOTE: If the battery performs abnormally, test the battery.

1.

Clean the battery terminals.

2.

Connect the positive cable (A) to the battery.

NOTE: Always connect the positive side first.

3.

Connect the negative cable and battery sensor (B) to the battery.

4.

Apply multipurpose grease to the terminals to prevent corrosion.

1.

After installation, check that all tubes, hoses, and connectors are installed correctly.