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S54 Engine Fuel Injectors Replacement
 
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Pelican Technical Article:

S54 Engine Fuel Injectors Replacement

Nick Czerula

Time:

2.5 hours

Tab:

$400

Talent:

*****

Tools:

Set of sockets (10mm), flathead screwdriver, clean rags

Applicable Models:

BMW E46 M3 Coupe/Conv (2006)
BMW Z4 Coupe/Conv (2006-08)

Parts Required:

Fuel Injectors, fuel injector O-rings, air tube O-rings

Hot Tip:

Work with a cool engine and relieve fuel system pressure

Performance Gain:

Clean and even flowing fuel injectors

Complementary Modification:

Replace with performance injectors

BMW Z4 models equipped with a S54 6-cylinder engine utilize one fuel injector per cylinder. Each fuel injector is an electrically controlled solenoid which, when triggered by a pulse from the engine control module, sprays a precisely metered amount of atomized fuel directly into the cylinder head intake port. The ECM supplies constant power to the injectors; the injector opening is controlled by the groundside of the circuit. Since fuel pressure at the injectors is (relatively) constant, the length of time (in milliseconds) of grounding pulse from the ECM determines the amount of fuel injected.

Over time fuel injectors can become restricted or fail electrically. If you have an injector giving you a problem, I suggest replacing them in sets of six. This way you maintain an even flow from all the injectors. If you are removing fuel injectors to replace the intake manifold and you plan to reuse the fuel injectors, replace all the fuel injector sealing O-rings.

S54 engines utilize standard style fuel injectors that mount in each throttle body and spray fuel on the backside of the intake valves. The injectors' shared fuel supply is a steel fuel rail. To remove an injector, you have to disconnect the electrical connectors to all the injectors. Then remove the fuel rail with all injectors attached to it. Individual injectors are then separated from the fuel rail, as needed.

In this tech article, I will describe how to replace each style of fuel injector.

Keep in mind that when your car was serviced before, parts may have been replaced with different size fasteners used in the replacement. The sizes of the nuts and bolts we give may be different from what you have, so be prepared with different size sockets and wrenches.

Protect your eyes, hands and body from fluids, dust and debris while working on your vehicle. If you're working with the electrical system, disconnect the battery before beginning. Always catch fluids in appropriate containers and properly dispose of any fluid waste. Recycle parts, packaging and fluids when possible. Do not work on your vehicle if you feel the task is beyond your ability.

Vehicle models change and evolve, as they grow older, so the vehicle shown in our illustrations may vary slightly from yours. If something seems different, let us know and share your info to help other users. Do yo have questions or want to add to the article? Leave a comment below. When leaving a comment, please leave your vehicle information.

Disconnect the negative (-) battery cable. See our tech article on Battery Connection Notes.

It's a good idea to relieve fuel system pressure before beginning. This will minimize the amount of fuel spilled. The best way to relieve fuel system pressure is to remove the fuel pump fuse, then start the vehicle until it stalls. See our tech article on fuel pump testing for more information, or use the fuse application guise supplied with your vehicle.

S54 engines utilize standard style fuel injectors that mount in each throttle body and spray fuel on the back side of the intake valves.
Figure 1

S54 engines utilize standard style fuel injectors that mount in each throttle body and spray fuel on the back side of the intake valves. The injectors' shared fuel supply is a steel fuel rail (green arrow points to air tube / fuel rail). To remove an injector, you have to disconnect the electrical connectors to all the injectors (red arrow points to main injector harness housing). Then remove the fuel rail with all injectors attached to it. Individual injectors are then separated from the fuel rail, as needed. 

To remove the breather hoses, squeeze the collar on the hose at the valve cover and pull it straight up.
Figure 2

To remove the breather hoses, squeeze the collar on the hose at the valve cover and pull it straight up. Detach the solenoid and hose from the mount (green arrow).

To remove the crankcase breather hose assembly (inset), cut the rubber hose clamp (red arrow) using diagonal pliers.
Figure 3

To remove the crankcase breather hose assembly (inset), cut the rubber hose clamp (red arrow) using diagonal pliers. Then remove it from the engine.

Working at the air tube, squeeze the hose collar (green arrows) and remove it.
Figure 4

Working at the air tube, squeeze the hose collar (green arrows) and remove it.

Then release the fuel injector harness housing from the fuel injectors.
Figure 5

Then release the fuel injector harness housing from the fuel injectors. I find the easiest way to do this is to use a large flathead screwdriver (red arrow) and gently pry up at each fuel injector (green arrows). This will release the spring clips that hold the electrical harness to the fuel injectors. When you do this, be sure to lever straight up. Also be sure the flathead is next to the fuel injector connector you are releasing. Work your way down the injector electrical harness and disconnect each fuel injector.

Pull the harness housing up to confirm it is detached (red arrow).
Figure 6

Pull the harness housing up to confirm it is detached (red arrow).

Working at the air tube, remove the two 10mm mounting fasteners (red arrows).
Figure 7

Working at the air tube, remove the two 10mm mounting fasteners (red arrows).

Use a pry bar (red arrow) and gently lever the air tube straight up (green arrow).
Figure 8

Use a pry bar (red arrow) and gently lever the air tube straight up (green arrow).

Lift the air tube up to remove it.
Figure 9

Lift the air tube up to remove it. Note the connecting pipes (red arrows) may stay in the throttle bodies. Be sure to remove them all from the air tube and throttle bodies to clean and replace the sealing O-rings. Open the wiring harness clips (green arrows). Then remove the air tube from the engine.

Working between injectors 5 and 6, remove the fuel feed line (green arrow) clip (red arrow), by levering it out.
Figure 10

Working between injectors 5 and 6, remove the fuel feed line (green arrow) clip (red arrow), by levering it out.

Use a pry bar (green arrow) and gently lever the front of the fuel rail straight up (red arrow).
Figure 11

Use a pry bar (green arrow) and gently lever the front of the fuel rail straight up (red arrow).

Use a pry bar and gently lever the rear of the fuel rail straight up.
Figure 12

Use a pry bar and gently lever the rear of the fuel rail straight up. Place a rag near the fuel feed line. As when detached, fuel will leak out (red arrow). Be prepared to catch leaking fuel in a suitable container.

Then pull the fuel rail straight up (red arrow) and out of the engine.
Figure 13

Then pull the fuel rail straight up (red arrow) and out of the engine. Be careful not to damage a fuel injector when removing it.

To remove individual fuel injectors, remove the retaining clip (red arrow) by sliding it off the fuel rail using a flathead screwdriver.
Figure 14

To remove individual fuel injectors, remove the retaining clip (red arrow) by sliding it off the fuel rail using a flathead screwdriver.

Then pull the fuel injector straight out of the fuel rail.
Figure 15

Then pull the fuel injector straight out of the fuel rail. When pulling the fuel rail up and out of the cylinder head, be careful not to damage any of the fuel injectors. If the injectors won't budge, use silicone spray to lubricate the injector holes. Doing this should help them slide out. Before reinstalling fuel injectors, replace the sealing O-rings. Before reinstalling fuel injectors, lubricate the sealing O-rings. I like to use silicone grease that is safe for use on rubber. This helps the injectors slide into the cylinder head with ease. Evenly press the fuel rail with the injectors into the throttle bodies. Be sure all of the injectors are properly seated. You can confirm this by checking if the mounting tabs are aligned with the bores for the fasteners. Install the fuel rail / air tube fasteners and tighten. Then install the fuel feed line-retaining clip. Be sure the fuel injector retaining clips are fully engaged. They should sit in the groove in the fuel injector and snap onto the fuel rail. Reassemble the remaining items, and check that there are no fuel leaks.

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Page last updated: Sat 12/3/2016 02:58:40 AM