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Intake Air Ducts Replacement
 
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Pelican Technical Article:

Intake Air Ducts Replacement

Nick Czerula

Time:

2 hours2 hrs

Tab:

$50

Talent:

***

Tools:

Flathead screwdrivers, T25 Torx driver

Applicable Models:

BMW Z4 Convertible (2003-06)
BMW Z4 Coupe (2006)

Parts Required:

Intake air ducts, hose clamps, intake air housing

Hot Tip:

Work with a cool engine

Performance Gain:

Car will run well

Complementary Modification:

Change engine air filter

The digital motor electronics (DME) engine management system in BMW Z4 vehicles receives input signals from a variety of sensors in order to meter fuel and regulate ignition timing. The most important sensors are as follows:

  • The mass airflow (MAF) sensor ahead of the air filter housing detects the mass and temperature of air entering the intake.
  • The engine coolant temperature (ECT) sensor detects coolant temperature at the cylinder head.
  • The crankshaft position (CKP) sensor detects crankshaft TDC position.
  • The camshaft position (CMP) sensor(s) detect cylinder firing position as well as camshaft timing advance or retard.
  • The engine knock sensor(s) detect pre-ignition or detonation.
  • The oxygen sensors detect oxygen content (and therefore engine combustion efficiency) in the exhaust stream.
  • The accelerator pedal sensor detects driver input for power and acceleration.
  • The radiator outlet hose coolant temperature sensor detects the temperature of coolant leaving the bottom of the radiator.

The mass airflow (MAF) sensor is suspended in the engine intake air stream before air enters the throttle housing. The sensor element (a thin film of metal, the so-called hot-film sensor) is heated electrically and the ECM monitors its temperature. Fluctuation in the amount of current needed to maintain a steady temperature in the film indicates fluctuations in the mass of air flowing through the intake. The ECM uses this information to calculate the volume of fuel to inject.

The MAF sensor is attached to the air intake housing. When an intake air duct after the sensor cracks or tears, extra air may be routed around the MAF sensor and therefore the MAF sensor signal will become unreliable. Air entering through the tear in the duct is unmetered and the engine management system cannot calculate fuel injection based on it. Engine drivability may suffer, or you may have a rough idle, or hard start or a malfunction indicated light (MIL or Check Engine light) that is ON with fuel trim faults.

Be sure to inspect your intake air ducts each time you service your vehicle. This will uncover problems you can prevent by replacing dry rotted or cracked air ducts.

When replacing your intake air ducts, replace them in pairs. If you are removing both and only one is cracked, it still makes sense to replace both.

To avoid marring the paint and trim, work with a plastic prying tool or wrap a screwdriver tip with masking tape before prying out body or interior items.

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 you have questions or want to add to the article? Leave a comment below. When leaving a comment, please leave your vehicle information.

Z4 models with a S54 or M54 engine have one main duct (yellow arrow) that runs to the intake air housing (red arrow).
Figure 1

Z4 models with a S54 or M54 engine have one main duct (yellow arrow) that runs to the intake air housing (red arrow). This duct can crack or tear over time, causing unmetered air leaks and a check engine light.

Start by removing the plastic line clipped to the intake air housing.
Figure 2

Start by removing the plastic line clipped to the intake air housing. Pull the line (red arrow) straight up to remove it from the mounts.

Then, disconnect the mass airflow sensor electrical connector by squeezing the release tabs and pulling it straight off.
Figure 3

Then, disconnect the mass airflow sensor electrical connector by squeezing the release tabs and pulling it straight off.

Next, you will unclip the five-air filter housing retaining clips (red arrows).
Figure 4

Next, you will unclip the five-air filter housing retaining clips (red arrows). Lift them up and unhook them from the lid of the intake air housing.

Using a flathead screwdriver, loosen the intake air duct hose clamp (red arrow).
Figure 5

Using a flathead screwdriver, loosen the intake air duct hose clamp (red arrow).

Then detach the intake air housing from the duct (red arrow) and remove the housing lid from the engine.
Figure 6

Then detach the intake air housing from the duct (red arrow) and remove the housing lid from the engine. If you're replacing the lid for a plugged emission filter, reverse the steps and install a new lid. You will have to transfer the mass airflow sensor over to the new lid.

Next, you will have to remove the plastic line at the duct.
Figure 7

Next, you will have to remove the plastic line at the duct. Squeeze the plastic collar (red arrows) and pull it straight off. Then loosen the duct hose clamp (yellow arrow). Pull the duct off the intake plenum to remove it.

Once the duct is removed, inspect the nipple for the plastic line (red arrow).
Figure 8

Once the duct is removed, inspect the nipple for the plastic line (red arrow). I have seen a few of these broken and causing fault codes for fuel trim.

To remove the lower intake air housing, lift up on the right corner while using a prybar (red arrow) to gently lever the rubber bushings (yellow arrows) off the posts.
Figure 9

To remove the lower intake air housing, lift up on the right corner while using a prybar (red arrow) to gently lever the rubber bushings (yellow arrows) off the posts.

Now, you can remove the lower housing.
Figure 10

Now, you can remove the lower housing. When installing, be sure the lower mount (red arrow) in in place. If missing, the intake air housing will rattle and may break. Reverse the steps to install the housing and new ducts. Align and secure the housing before tightening the duct clamps. This will ensure a long lasting replacement duct.

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Page last updated: Sat 12/3/2016 02:56:03 AM