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Most of the required parts... note that I didn't realize the heat shield
would be so brittle, so didn't have one on hand prior to beginning work. |
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Disconnect battery positive lead.
- make sure your
seats/mirrors are in their #1 saved position so you can return them after
reapplication of power.
Remove engine cover.
- Note that I
realized three of the four foam donuts that sit on the cover’s mounting pegs
were gone - I later found them sitting down on the intake manifold. |
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Remove Idle Control Valve if so equipped
- disconnect
wire harness from valve (A)
- disconnect
plumbing (at both ends) running between valve and intake flex hose, move
aside for now (B)
- carefully
disengage (don’t break off mounting feet) rubber hose clamp surrounding
valve from bracket (C)
- rotate valve
upward to disconnect from throttle body, set valve aside.
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Disconnect and remove flex line between MAF and
ASC throttle body.
- release hose
clamps on both ends (A)
- reach
underneath and disconnect flex hose from intake resonator box by supporting
resonator while steadily pulling up on underside of hose (B)
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Engine Cover Supports
- Carefully
disconnect red snap fitting at throttle cables (it will probably break)
- remove four
10mm bolts, two on each support (A). Don’t drop bolts. Set supports aside |
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Fuel Lines
- remove fuel
lines at driver’s side rear of engine block (four places). Grasp hose
portion and push toward connector. Using other hand, press black lock ring
toward hose, then release hose from pipe. CAUTION: fuel may be under
significant pressure.
- Using a baggie
and zip tie on EACH of four fuel pipes, seal off pipes (two on intake
manifold and two on fender well). Place removed hoses in a clean environment
- ie., inside a large ziplock bag. |
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Driver’s side electrical harness
- remove valve
cover plate (A) - carefully pry up two small plastic covers to gain access
to mtg bolts. Remove 10mm bolts. Pry plate away from valve cover with hands.
Remove and set aside.
- disconnect
coils (B). On each of four coils, lift silver-gold connector lock clip, then
disconnect harness connector from coil.
- disconnect
circular knock sensor harness (C) (there may be two such connectors on VANOS
motors. Also on VANOS motors I think there is a second cam position sensor
harness).
- remove two
10mm nuts (D) attaching harness covering (black plastic rectangular box) to
head. Set nuts aside.
- disconnect
electronic harness from rear-most injector (E) - working from bottom of
connector, press metal retaining clip upward to release.
- disconnect
harness cover from fuel injectors. The driver’s side cover is essentially
one large connector, providing electrical connection to the front three
injectors on this side. Grasp the cover/box with both hands and pull
directly up and away from the injectors (straight away from the injectors, a
45 degree angle from the vertical) - try to disconnect the cover from all
three injectors at the same time. Be prepared for the release: stop pulling
as soon as the cover comes free. Allow cover to simply lay on head at this
point. |
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Accelerator Cables
- move main
throttle lever backward with one hand while disconnecting both accelerator
and cruise control cable ends from lever - the plastic retainers unsnap
forward (A).
- remove
throttle cable bracket from front of throttle body - 2x T30 Torx bolts (B).
This way you don’t need to readjust the cable position when you’re done.
- move ASC
throttle lever (C) (on underside of secondary throttle body) backward
(clockwise looking down) to create slack in the ASC cable. Remove the cable
from the lever by unsnapping barrel end from lever and threading cable thru
slot. Pull ASC cable from mounting lug (D) on lower-right side of secondary
throttle body. You do not need to remove any more of the ASC cable. |

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Passenger side electrical harness
- remove valve
cover plate (A) (the BMW plate) - same as driver’s side.
- disconnect
coils - same as driver’s side.
- disconnect
circular knock sensor harness (B) and crankshaft position sensor harness (C)
- lay each harness out of way toward front of motor.
- remove two
10mm nuts (D) attaching harness cover head. Set nuts aside.
- disconnect
harness cover from fuel injectors. The passenger side cover is the same as
the driver’s side except that it connects to all four injectors. Allow cover
to simply lay on head at this point.
- disconnect
electrical connector from fuel tank breather valve (E) (driver’s side front
of engine block)
- disconnect
electrical connector from main and secondary throttle position sensors (F). |

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Vacuum Control Plumbing
- locate black
pipe that runs front/back along upper driver’s side of intake manifold.
Remove single 10mm bolt (A) holding bracket at front-center of intake
manifold (note: rear bracket should already be loose when driver’s harness
cover was removed).
- follow black
pipe rearward - it connects to a rubber hose, which in turn runs into a ‘T’
connector (B). The hose that runs from this ‘T’ over to the rear of the
intake manifold must be disconnected at the manifold (C). This is a
large press-fit ‘L’ connector which runs into a rubber grommet in the rear
face of the manifold. Carefully work the ‘L’ fitting loose from the grommet,
twisting and pulling it rearward from the manifold.
- Return to the
black pipe where it connects to a rubber hose - cut and remove the factory
crimp connector (D) (don’t damage the hose) and disconnect the black vacuum
pipe from the hose. At this point the intake manifold vacuum plumbing is
disconnected from the car. During reassembly you will replace this crimp
connector with a screw-type hose clamp. Allow the black pipe to rest on the
intake manifold.
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Engine Vent Tube
- PITA Alert!
The vent tube is located under the intake manifold (dotted lines in photo),
runs along the driver’s side head/block, and connects the block to the
intake manifold. This tube must be disconnected from the intake manifold
prior to the manifold’s removal.
- Remove the
driver’s side air duct between the cabin air filter box and firewall - at
the filter box, release the retainer strap, then rotate the duct 45 degrees
counterclockwise and pull forward away from the firewall. Set duct aside.
- The vent tube
mounts to the intake manifold (A) via an o-ring sealed slip fit. The tube is
retained by a spring clip (B), which snaps around the tube (C) and clips
over the manifold’s fitting (A). This clip is accessed at the driver’s side
rear of the intake manifold, down low. Using a small screwdriver, gently pry
this clip up away from the tube. If the clip slides forward on the tube
under the manifold, don’t worry - you’ll retrieve it later. If it falls off
down into the motor, get it now before you forget.
- Now slide the
vent tube (C) forward off the connector fitting - it will probably be stuck,
so judicious use of a large screwdriver to help pry it away may be called
for. Work slowly and don’t break anything. Slide the tube all the way
forward until you see that it is completely disconnected from the fitting.
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