BMW N55 Fuel Injector Replacement – 6 Cyl. Turbo 1,3,5,7,X3,X6,Z4 Series

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bmw n55 fuel injector tool

BMW N55 Fuel Injector Replacement – 6 Hours

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The BMW Repair Guide used this 2011 335ci for the following article. To see other repairs on our site using this actual car, please click on the image below!

 

 

Please read the following before beginning this repair. 

  1. Before starting this advanced repair, please we aware that you will need a diagnostic tool that has the ability to calibrate the flow rates of your new injectors. The BMW Repair Guide uses ISTA+ (Rheingold) software to program their injectors, but most other popular BMW diagnostic tools have this ability including the Schwaben/Foxwell nt510. YOU MUST calibrate your new injectors after installation in order for them to operate correctly. Please see our video on injector calibration at the end of this article.
  2. You will also need a special fuel injector extraction/installation tool to do this repair. We have prepared a detailed video on how to use this tool – please see section 4 below to view video. Please see our links below in “Tools and Supplies” on where to purchase this tool prior to starting the repair. 
  3. This repair is for the BMW N55 direct injection engine only. Please click on the following box to verify this repair applies to your vehicle before starting:
repair models

A BMW fuel injector replacement on the N55 twin turbo six cylinder engine is a lengthy repair, but will save you thousands of dollars on parts and labor by “Doing It Yourself” and not going to your local repair shop.

One of the unfortunate evils of owning a BMW with the N55 twin turbo engine is increased maintenance. As wonderful as these engines are, they are notorious for their mechanical issues. Add the sad fact that many of the original owners of these cars didn’t properly maintain them, and you have a recipe for impending disaster…especially on N55 engines with over 100,000 miles.

The fuel injectors are a known weak point on the N55 direct injected engine and are prone to failure.

When you get north of 100,000 miles, you can pretty much expect to perform a BMW fuel injector replacement on these engines. Injectors get fouled over the years from poor fuel choices and not regularly using a good fuel additive like Techron. Driving a vehicle on fouled or clogged injectors can cause further damage and may ultimately lead to injector failure.

The BMW N55 engine uses direct injection which further complicates the matter. Direct injection is a form of fuel injection, where the gasoline is atomized directly into the cylinder under extremely high pressure. Direct injectors are prone to carbon buildup and are subjected to a continuously brutal environment inside the combustion chamber of the engine.

Fuel injectors in the BMW N55 engine are also prone to sticking open. This is a very serious condition where the injector continues to spray fuel into the cylinder. As the fuel builds up in the combustion chamber(s) it will cause multiple cylinder misfires and plumes of noxious white smoke to be ejected from the tail pipes. Driving the car in this condition will cause catastrophic damage to the engine and a tow truck ride to the scrap yard.

Using the correct fuel injector removal tool
There seems to be some confusion as to what tool and method is best for extracting a fuel injector from the cylinder head of a N55 engine. The first rule of thumb is this; if your vehicle is close to/over 100,000 miles, most likely your fuel injectors will be stuck and require a removal tool to get them out.

bmw n55 fuel injector tool
Fuel injector removal/installation tool for the N55 engine with a horizontal mounting bolt configuration.

Secondly, only use a BMW OEM extraction/installation tool and a good low torque wrench to remove and reinstall the injectors in your N55 engine. There are a lot of BMW owners out there that have come up with creative ways to pull out a stuck injector…from using coat hangers to dental picks and pliers. We urge our readers to use the proper tool and follow our instructions below on how to use it. The money saved by doing this repair yourself will exponentially outweigh the cost of buying the tool. And most importantly you will avoid any damage to the new injector or your engine.

Be aware that are two different tool mounting configurations in the BMW N55 engine; a horizontal configuration and a vertical configuration. Always check your mounting bolt layout before ordering your tool. 

Parts, Tools and Supplies

Affiliate link disclosure – The BMW Repair Guide uses affiliate links in their site. For more information on affiliate links, please click here.

Parts

Part #1 Injectors. We give you two choices…most and least expensive. Choose from one of two options:
Option 1 – Genuine BMW injectors (most expensive):

Part NameQuantityBMW Part #Description
Fuel injector – high pressure 68607613537568607for N55 engine vehicles only with production date up to 01/2011
Fuel injector – high pressure 97870613647597870for N55 engine vehicles only with production date after 01/2011

OR
Option 2 – OEM Bosch injectors (least expensive):

Part NameQuantityBMW Part #Description
Fuel injector – high pressure 68607B613537568607for N55 engine vehicles only with production date up to 01/2011
Fuel injector – high pressure 97870B613647597870for N55 engine vehicles only with production date after 01/2011

 


Part #2 injector decoupling element. Order one for each injector.

Part NameQuantityBMW Part #Description
Fuel Injector decoupling element 77649613537577649One needed for each injector ordered

 

Tools and Supplies
Diagnostic scanner (must have ability to calibrate fuel injectors)
Fuel injector installer/remover – horizontal mount 0075
Fuel injector installer/remover – vertical mount 0076
Torque wrench- low range
24mm crows foot socket
E16 external torx socket
14mm open end wrench
8mm deep socket wrench
8mm nut driver
8mm hex socket
Screwdriver – flat blade
Long reach needle nose pliers
Socket extensions
T25 torx bit

Procedure

Always check the physical part number (the number stamped on the part…not the one on the packaging) before starting any repair. It is not unheard of to have parts sent in the wrong box! It only takes a minute to check and will save you a lot of agony…especially if you have your vehicle disassembled and have the wrong part to complete the job.

  1. Use a socket wrench to disconnect the negative terminal from the battery before starting this repair. Always cover the terminal with a clean rag to avoid accidental contact during the repair. If working on a vehicle with 2 batteries (8 series), disconnect the negative terminal from both batteries. ALWAYS disconnect the battery(s) before performing any type of mechanical repair, especially in the engine compartment.battery disconnect

 

Section 1 – Cabin filter housing removal

  1. Remove the five 8mm screws anchoring the upper filter housing. Remove upper filter housing from vehicle.bmw 335i cabin filter
  2. Unsnap and remove the two side covers (both left and right) from the lower filter housing and remove from vehicle.bmw 335i cabin filter
  3. Remove the right and left electrical connections from the lower filter housing.bmw 335i cabin filter bmw 335i cabin filter
  4. Use an 8mm nut driver to remove the two screws anchoring the lower filter housing to the vehicle. There is a screw on both the right (passenger) and left (drivers) side of the lower filter housing.bmw 335i cabin filter
  5. Remove the lower filter housing from the vehicle.bmw 335i cabin filter

 

Section 2 – Intake air duct removal

  1. Use a flat blade screwdriver to remove the Mass Air Flow (MAF) electrical connector from the front duct.bmw 335i air intakebmw 335i air intake
  2. Loosen hose clamp connecting air cleaner assembly to front duct. Unclip the lid of the air cleaner assembly and remove. bmw 335i air intakebmw 335i air intakebmw 335i air intake
  3. Remove the 10mm bolt anchoring the top air duct assembly to the cylinder head. bmw n55 fuel injector
  4. Remove the electrical connector from the crankcase vent hose.bmw n55 fuel injector
  5. Use a flat blade screwdriver to pry the crankcase vent hose off of it’s cylinder head connector. This part is made of stiff plastic that becomes very brittle with age, and is prone to breaking during removal. In fact you can see in the step 4 photo above we broke ours by accident. If you break your vent hose, click to reorder here (BMW part # 11127584128).bmw n55 fuel injectorbmw n55 fuel injector
  6. Use a T25 torx bit on a long extension to remove the screw securing the air duct assembly to the bottom air duct. BE CAREFUL…don’t drop screw into engine.bmw n55 fuel injector
  7. Remove the air duct assembly from engine.
  8. Use an E16 external torx socket to remove the bolt securing the right strut brace to the vehicles body and pivot out of the way. This needs to be done to gain access to cylinder 5 and 6 fuel injectors.bmw n55 fuel injectorbmw n55 fuel injector

 

Section 3 – Preparing for fuel injector removal

  1. Remove the ignition coil from the cylinder in which you are performing the fuel injector service by releasing the electrical connector and pulling it straight out of spark plug tube. Use a socket extension to help pull the coil out if it is stuck. Remove the ignition coil from the adjacent cylinder as well.bmw n55 fuel injectorbmw n55 fuel injectorbmw n55 fuel injector
  2. Use a 14mm open end wrench to loosen the fuel line nuts on both cylinders. ***Fuel line may be under pressure. Have a rag ready to catch any fuel that may be ejected from fuel line. Remove fuel lines from engine. bmw n55 fuel injectorbmw n55 fuel injector
  3. Remove both fuel injector electrical connectors. These connectors can be tricky to remove. Insert a small flat blade screw driver down the left side of the connector and it will release and pull straight out (see image below). DO NOT try and pull out with force…you will break the connector and hence be in a world of sh!t.bmw n55 fuel injector
  4. Use an 8mm socket to remove the ground wire nut. Remove ground wire from cylinder head.bmw n55 fuel injectorbmw n55 fuel injector
  5. Optional step – Remove the inspection screw plug using an 8mm hex socket. This is a completely optional step, and has no bearing on completing this repair. It is simply an inspection hole that is used to view the injector slot during routine maintenance. We like to remove it so we can lubricate the threads in the event it needs to be used at a later date to inspect the injectors.bmw n55 fuel injector
  6. Use a deep 8mm socket to remove the front bolt securing the support bridge to the engine.bmw n55 fuel injector
  7. Use an E8 external torx socket to remove the rear bolt securing the support bridge to the engine. bmw n55 fuel injector
  8. Use the E8 external socket to also remove the lower bolt securing the injector cover plate to the engine.bmw n55 fuel injector
  9. Remove the clamping plate and the support bridge from the engine.bmw n55 fuel injector
  10. Remove the injector cover plate from the engine.bmw n55 fuel injector
  11. Using an E10 external torx socket, remove the bolt securing the bottom hold down bracket to the cylinder head.bmw n55 fuel injectorbmw n55 fuel injector
  12. Use a pair of long nose pliers to extract the bottom hold down bracket from engine. It’s a bit tricky so use patience…you have to tilt the bracket to coax it out from around the fuel injectors.bmw n55 fuel injectorbmw n55 fuel injector

 

Section 4 – Removing and installing fuel injectors

Please watch the following video on how to remove and install your fuel injectors using the N55 fuel injector tool. We have also included written instructions with photos after the video.

  1. ***Before proceeding, please be sure you are using BMW tool #130270 to extract the fuel injectors on the N55 engine (see our discussion above). Before placing the extraction tool in the engine, unscrew the two threaded pullouts (A) so they are at the halfway mark in the tool.bmw n55 fuel injector toolbmw n55 fuel injector tool
  2. Place the tool in the injector slot. Make sure the threaded sleeves and pullouts (A and B) are lined up over the fuel injectors. Hand tighten the two anchor bolts (C) into the cylinder head. Double check to make sure tool is square and everything is lined up correctly.bmw n55 fuel injector
  3. Gently turn the threaded pullouts (B) counterclockwise until they stop turning. DO NOT hand tighten. You are simply lowering the threaded sleeve (A) onto the injector head in preparation for the next step (see above video).bmw n55 fuel injector
  4. Hand tighten the threaded sleeves (A) clockwise onto the injectors until they are snug. ***If you are only removing one injector, only tighten the threaded sleeve (A) on the injector being removed (leave the other one loose) (see video).bmw n55 fuel injector
  5. Tighten the two anchor bolts (C) and torque to 9 Nm (7 ft-lb) (80 in-lb).bmw n55 fuel injector tool
  6. Attach a 24mm crow’s foot socket to a low torque wrench. This will require the use of socket reducers since the 24mm crow’s foot will be ½” drive, and most low torque socket wrenches are ¼” drive. Please see the following photo to see how we handle it.bmw n55 fuel injector tool
  7. Set the torque wrench to 5 Nm (3.5 ft-lb). Attach the crow’s foot to the threaded pullout (B) (NOT the threaded sleeve (A)) and turn CLOCKWISE. Remember, the threaded pullout has a reverse thread so turning clockwise will pull the injector out. Try not to exceed the 5 Nm on the torque wrench. There should not be any reason why you should exceed 5 Nm when extracting the injector, unless you are turning the wrong way! bmw n55 fuel injector
  8. When the injector(s) are extracted, loosen the anchor bolts and remove the tool with the injectors attached.bmw n55 fuel injector tool
  9. Place the tool on a bench and remove the old injector. bmw n55 fuel injector
  10. Unpack the new injector. Look at the part number side to verify it is correct (we suggest taking a photo). Flip the injector over and take another photo of the numbers on that side. ***You will need the three digit calibration number to program the flow rate in the new injector. DO NOT install the new injector without writing down this number. We highly recommend taking a photo of both sides of the injector before installing so there are no issues during the calibration phase.bmw n55 fuel injectorbmw n55 fuel injector
  11. Verify that the injector seal is installed on the new injector. All new BMW injectors ship with the injector seal already installed.bmw n55 fuel injector
  12. Unpack the new decoupling element. Notice that the sides are different. One side has a thin ring. bmw n55 fuel injector
  13. Slide the decoupling element on the new injector with the thin ring facing the inside as shown in the following image. Press on the decoupling element until it snaps into place.bmw n55 fuel injectorbmw n55 fuel injector
  14. The new injector can now be installed. Start by placing the injector LOOSELY back into the engine. Do not apply force.bmw n55 fuel injector
  15. This is a very important step, so please follow carefully. Note the location of the electrical connector and the threaded head of the injector. These MUST line up with the cutouts in the cover plate, or you will not be able to complete the installation. Make sure the injector is installed with the electrical connector on the left side and the injector threads are vertical so they match the cover plate cutouts (see image below).bmw n55 fuel injectorbmw n55 fuel injector
  16. Unscrew (turn clockwise) the threaded pullouts (B) so they all the way out of the tool.bmw n55 fuel injector
  17. Install tool into the injector slot and attach to fuel injectors as outlined in steps 2-6 above.
  18. Set the torque wrench to 4 Nm (3 ft-lb).
  19. Turn the threaded pullout (B) COUNTER-CLOCKWISE, pushing the fuel injector into the cylinder head until torque is reached. bmw n55 fuel injector
  20. Release retaining pin by pushing in (use a pair of pliers if necessary). Releasing the retaining pin allows the threaded sleeve (A) to be removed.bmw n55 fuel injector
  21. Remove threaded sleeve (A) by turning counterclockwise, using a 14mm open end wrench to first loosen it and then finishing with your fingers.bmw n55 fuel injector
  22. Temporarily install cover plate to insure injectors line up with openings. If they do not, use a 14mm open end wrench and VERY GENTLY turn the injector in the direction needed so it lines up with cover plate. Once again, we stress VERY GENTLE micro turns until it lines up correctly.
  23. Injector is now properly installed. Repeat with other injectors being replaced.
  24. When finished installing injector(s), reassemble engine following steps in Section 1, Section 2 and Section 3 above in reverse order.

 

Section 5 – BMW N55 Fuel Injector calibration – injector quantity compensation

You will need to calibrate your BMW N55 fuel injector flow rates before you can run the engine. The reason the injectors must be calibrated is that the vehicle’s DME (Engine Control Unit) does not know what the true flow rate of the injectors are…just what they are supposed to be for the engine to operate efficiently. Therefore, we must tell the DME what the true flow rates are. With the true rates stored in it’s memory, the DME will calibrate the injectors so they all spray fuel into the cylinder at the same rate.

In order to calibrate the injectors you will need a diagnostic tool that supports this function. The BMW Repair Guide uses ISTA+ (Rheingold) to calibrate their direct fuel injectors, although many BMW handheld diagnostic tools on the market support this function, including the popular Schwaben/Foxwell nt510 and the Autel MX808.

The following video show you how to calibrate the injectors using ISTA+:

 

BMW N55 Fuel Injector Replacement finished
If you have any questions or comments, please feel free to contact us. And congratulations for Doing It Yourself!

The Repair Difficulty Level displays graphically how challenging the repair is, from easy to advanced. Easy repairs usually require very few tools, have short repair times and do not require jacking and supporting the vehicle. As the difficulty level rises, expect the repair to demand more time, specialized tools, and better understanding of mechanics to complete the job.

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