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Fuel Injector Replacement
 
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Pelican Technical Article:

Fuel Injector Replacement

Jared Fenton

Time:

3 hour3 hr

Tab:

$180 to $1,200

Talent:

****

Tools:

Screwdrivers, T30 Torx driver, pliers, 17, 19mm wrenches, small pick

Applicable Models:

Porsche 955 Cayenne S (2003-08)
Porsche 955 Cayenne Turbo (2003-08)

Parts Required:

Fuel injectors, fuel injector seals

Hot Tip:

Keep a fire extinguisher handy

Performance Gain:

Smoother running engine

Complementary Modification:

Clean out throttle body

Is your car running sluggishly? Are you noticing a slight stumble as you drive? Chances are, your fuel injectors need to be cleaned. In this tech article, I will go over the steps in removing the fuel injectors and cleaning them out. This article applies to the Porsche Cayenne, however the principles behind this apply to nearly every car in general. Usually, most people just run a can of fuel injector cleaner in a full tank of gas. I would also recommend this, but in cases of cars that have been poorly maintained or have been sitting for a while, the only way to get those injectors truly clean is to pull them out.

One of the nice features of the Cayenne is the ODB2 system. This typically will throw a check engine light (CEL) in the event of an actual injector failure. Once you get a CEL, you'll want to use a code reader to extract the diagnostic trouble code (DTC) stored in the computer. Typically, this manifests as a P0201 thru P0208 code. For example, a P0206 code would indicate a problem with injector number 6.

Begin by removing the engine compartment covers; the engine covers themselves and also the throttle body (see our article on coil pack and spark plug replacement, engine cover removal and throttle body cleaning for more information).

Keep in mind that you will be working around raw fuel. It's a good idea to have a fire extinguisher nearby. Better safe than sorry. You'll also need to relieve the fuel pressure built up in the fuel rail, otherwise, you'll get a pressurized blast of fuel all over the place when you disconnect the feed line to the rail.

There are two methods you can use to relieve the fuel pressure built up in the rail. One involves removing the fuel pump fuses from the fuse box, then running the car until the engine dies. This method has the advantage of using up all the fuel in the rail; however, it may trigger a DTC indicating a failure in the fuel pump circuit. If you start the car and the CEL comes on, the DTC stored in the computer will need to be read and then cleared from the computer.

The other method of relieving pressure is removing the plastic caps from the ends of the fuel rail and pressing the Schrader valves inside. This method will not trigger a DTC, however you will have to hold a rag in front of the valve to catch the fuel escaping. You'll also need to drain the fuel rail of all the gasoline inside. Summed up, if you have a diagnostic scanner, use the fuse method. If not, use the valves on the ends of the fuel rail.

The fuel rail is held on to the intake manifold by four T30 Torx screws. The front two screws are easy to remove with, however the back two, particularly the one on the left side is a real challenge to reach. I've found that a long shafted T30 Torx driver and a U-joint makes the job a bit easier.

At this point, pull off the fuel rail from the top of the intake manifold. Use caution and work from the front of the car to the rear - pulling and making progress slowly. The injectors have small O-rings that are pressed into bores in the intake manifold - you are battling these O-rings as you lift up on it, and pull it out. Be careful of the injector tips - they are made of plastic, and are not available separately from the $150 injectors. Do not damage them.

After you have removed the fuel rail. Turn it upside down on your workbench to remove the injectors. Use a small pick to carefully remove the metal clips holding the injector to the fuel rail. Once the clips are removed, you can pull the injector out of the rail. It may take a little side-to-side pulling to free the injector from the rail.

With the injectors out of the manifold you can now take them to be cleaned and calibrated. Over the years, the injectors become dirty and may also not distribute flow evenly amongst all six. It costs about $150 for all six to be cleaned, tested, and calibrated. New injectors cost anywhere from $150-$200 apiece, making their replacement a somewhat pricey endeavor.

You'll need to relieve the fuel pressure inside the fuel rail prior to disconnecting the fuel line.
Figure 1

You'll need to relieve the fuel pressure inside the fuel rail prior to disconnecting the fuel line. There are two methods to do this. Shown here is the method using the fuel pump. On the rear right side of the engine compartment is the panel that covers the fuse box. Loosen and remove the two panel clips (green arrows) and remove the panel.

Pull the two fuse panel cover pins up (green arrows) up and out of the fuse box and remove the cover.
Figure 2

Pull the two fuse panel cover pins up (green arrows) up and out of the fuse box and remove the cover.

Now pull the fuses for the fuel pumps out of the fuse box.
Figure 3

Now pull the fuses for the fuel pumps out of the fuse box. These are fuses 13 and 14. The green arrows show the locations of the two fuses. Now start the engine and let it run until it dies. This will bleed off any remaining pressure in the lines.

The other method for relieving fuel pressure involves removing the two plastic caps off each end of the fuel rail and using a pin to press the Schrader valve in.
Figure 4

The other method for relieving fuel pressure involves removing the two plastic caps off each end of the fuel rail and using a pin to press the Schrader valve in. You'll want to have paper towels underneath to catch the fuel that will spray out.

Shown here is the fuel rail attached to the intake manifold (green arrow).
Figure 5

Shown here is the fuel rail attached to the intake manifold (green arrow). In order to remove the fuel injectors, you'll need to remove the fuel rail. Begin by squeezing the tabs on the breather hose connectors (blue arrows) and separating the hoses from the manifold. SeePicture 2 for clarification. Also take note of the fuel hose connection to the fuel rail (yellow arrow).

Squeeze the wide outer rings (green arrows) together on the breather hose connections at the top of the intake manifold and pull them out.
Figure 6

Squeeze the wide outer rings (green arrows) together on the breather hose connections at the top of the intake manifold and pull them out. You will need to use a little force to get them out.

Open the retaining clip shown here (yellow arrow) on the left cylinder head.
Figure 7

Open the retaining clip shown here (yellow arrow) on the left cylinder head. Once the breather hose is free of the clip, squeeze the two tabs holding the connector to the head and remove the breather hose.

Now disconnect the fuel rail from the supply line.
Figure 8

Now disconnect the fuel rail from the supply line. Use a 19mm wrench to hold the outer, hard line (yellow arrow) while you use a 17mm wrench to turn the fitting counter-clockwise (green arrow). Do not turn the outer line, just the inside one. Place a rag directly under the connection, as you're likely to have some fuel spill out.

Remove the front left T30 Torx screw (green arrow) holding the fuel rail to the intake manifold.
Figure 9

Remove the front left T30 Torx screw (green arrow) holding the fuel rail to the intake manifold.

Remove the front right T30 Torx screw (green arrow) holding the fuel rail to the intake manifold.
Figure 10

Remove the front right T30 Torx screw (green arrow) holding the fuel rail to the intake manifold.

Remove the rear left T30 Torx screw (green arrow) holding the fuel rail to the intake manifold.
Figure 11

Remove the rear left T30 Torx screw (green arrow) holding the fuel rail to the intake manifold. Also disconnect the electrical plugs going to each fuel injector (yellow arrow) You'll need to push the small wire clip inward and pull each plug off. This can be somewhat of a challenge due to the limited space around the injectors. I suggest using a small drift to carefully lever the wire clip in while pulling the plug off.

Shown here is the location of the right rear T30 Torx screw holding the fuel rail to the intake manifold (green arrow).
Figure 12

Shown here is the location of the right rear T30 Torx screw holding the fuel rail to the intake manifold (green arrow). Removing this screw is the hardest part of the job.

Reaching the back screw is always a chore.
Figure 13

Reaching the back screw is always a chore. A long shafted T30 Torx bit on the end of a U-joint with an extension bar helps, although it will be a challenge to find just the right angle. Be careful not to damage the hard plastic lines that run around this area.

Shown here is the rear of the fuel rail with the intake manifold removed from the engine.
Figure 14

Shown here is the rear of the fuel rail with the intake manifold removed from the engine. In thisPicture, you can get a better idea of the screw locations (green arrows).

Once all the mounting screws are removed, carefully pull up on the fuel rail to separate the fuel injectors from the manifold as shown here.
Figure 15

Once all the mounting screws are removed, carefully pull up on the fuel rail to separate the fuel injectors from the manifold as shown here. Take car to maneuver the rail around any electrical wires or hoses. Also inspect the mounting holes in the manifold. Clean up any dirt or pluck out any O-rings that might be left behind. Always put some shop rags or towels into the open injector ports to stop anything from falling into the intake manifold.

Shown here is the fuel rail, removed from the engine.
Figure 16

Shown here is the fuel rail, removed from the engine. Each of the eight injectors are secured to the rail with metal clips.

Use a small pick to carefully pull the retaining clip off the injector enough where you can grab it with your fingers and remove it.
Figure 17

Use a small pick to carefully pull the retaining clip off the injector enough where you can grab it with your fingers and remove it.

Note the grooves in the clip and also the fuel injector.
Figure 18

Note the grooves in the clip and also the fuel injector. When installing the new injector, it must line up to allow the clip to slide over both the lip on the fuel rail and also the injector.

Now simply pull the injector up and out of the fuel rail.
Figure 19

Now simply pull the injector up and out of the fuel rail. Be prepared for gasoline to trickle out.

Most new fuel injectors will come with new O-rings already mounted in place.
Figure 20

Most new fuel injectors will come with new O-rings already mounted in place. However, if the O-rings need to be installed, carefully pull them over the plastic lip on the end of the injector. You don't want to damage these. When installing the new injectors, it is a good idea to lightly coat the O-rings with silicone grease. This will allow the O-rings to slip into the mounting holes easier.

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Comments and Suggestions:
Lazo Comments: Hello Mike
Can you please guide me on wear to take my injectors from a2004 Porsche Cayenne to get cleaned and calibrated. I live in the San Fernando Valley.
Thank you
July 3, 2016
  Followup from the Pelican Staff: I would call Linder Tech fuel injector in Indy. - Nick at Pelican Parts  

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