LS3 Intake Manifold Removal from a Corvette
This can generally be done in an hour or less by any owner with basic mechanical experience
These instructions can also be followed for LS2 and LS7 model Corvettes. Other LS2 and LS3 vehicles may have slight variations in the procedure.

1. Disconnect the negative battery terminal.

2. Completely remove the intake tube with the Mass Air Flow Sensor that is attached to the throttle body. You will need to: 1. Disconnect electrical connection at Mass Air Flow Sensor 2. Pull off hose connection and 3. Loosen tube clamps.

3. Pull off the two fuel injector covers. Each is connected to the fuel rail at the top and has two rubber connectors at the bottom. Simply pull up firmly on them to remove them.

4. Disconnect the electrical connector on the throttle body.

5. Take throttle body off the intake manifold by removing 4 bolts. 

6. Disconnect the five connections at the front of the intake manifold as follows:
A. On the right side of the plenum opening as you are facing the front of the intake manifold, disconnect tube (5) by holding in the white locking connector while pulling on the tube.

B. On the left side, top front of the intake manifold is the MAP sensor (6). Disconnect electrical connector at MAP sensor. Below the MAP sensor disconnect tube (7a) by holding in the white locking connector while pulling on the tube.

C. On the left side under the MAP sensor connection on the throat of the intake manifold is a hose (7b) that can be pulled off. Disconnect tube (7c) by holding in the white locking connector while pulling on the tube.

7. Disconnect the two connections at the rear of the intake manifold as follows:
A. Disconnect tube (8) at the firewall on drivers side by holding in the white locking connector while pulling on the tube.

B. Disconnect brake booster hose (9) at the brake booster. Take the hose off the intake manifold after the manifold has been removed from the car.

8. Disconnect main fuel line where it attaches to the fuel rail. You will need a special tool for this that can be picked up inexpensively at most auto parts stores. First, remove metal retaining clip at this connection. Then insert plastic tool over tube on fuel rail and pull the tool toward you to release the connector in the main line. It is advisable to wrap a rag around the connection as you do this as there is some pressure within the line and a small amount of fuel will leak out when the pressure is released. Place a small rubber plug on the fuel rail to keep fuel from continuing to leak.

9. Remove wiring harness from the fuel rails. This is easily done with a door panel removal tool but can also be done with a flat blade screwdriver.

10.Disconnect electrical connectors at each fuel injector.

11.There are 10 bolts that hold the intake manifold to the heads as well as the fuel rails to the intake manifold. Loosen the last bolt on each side of the intake manifold closest to the firewall. You will need an 8mm combination wrench to loosen these.

12.These two bolts at the rear of the intake manifold cannot be removed until the manifold has been pulled forward slightly. It is easiest to put a small amount of masking tape on the bolts to hold them up while the intake manifold is being removed.

13.Remove the 8 remaining bolts that hold the fuel rail and intake manifold to the heads. Not all bolts are the same, so be sure to remember where each bolt and related bracket goes when reassembling.

14.Now the intake manifold and fuel rail assembly can be removed from the vehicle by gently lifting up while pulling forward slightly. Be careful at the back of the manifold to feed the brake booster hose around and over the top of the oil pressure sending unit and its related wire harness. If you’re not careful, you can damage the sending unit, or the wiring harness that attaches to it, by yanking the brake booster hose past it.


15.Once the intake manifold is off, remove the fuel rail from the intake manifold by pulling up evenly and firmly so the injectors pull out from their seats in the intake manifold. At this time, also remove the brake booster hose from the back of the manifold, remove the MAP sensor and remove all of the gaskets around each runner opening and the plenum opening. These can be reused when reassembling.

16.If you aren’t installing a new intake manifold immediately, clean up the engine and then put masking tape across all of the head ports so you don’t risk debris getting into your engine while the intake manifold is off.

Reinstall Tips:

Follow steps, above, in reverse.

Intake Bolt Tightening Sequence

Use a medium strength thread lock and tighten the intake manifold bolts a first pass in sequence to 5 N�m (44 lb in).
Tighten the intake manifold bolts a second pass in sequence to 10 N�m (89 lb in).

Tighten 4 throttle body bolts to 12 N�m (106 lb in).

Place a thin coat of oil on injector o-rings before inserting them into fuel rail and intake manifold.

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