5B1202 - HIGH FLOW CATTED DOWNPIPES N54 135i/335i

 5B1202 - HIGH FLOW CATTED DOWNPIPES
N54 135i/335i
Installation Instructions
Front
Downpipe
Rear
Downpipe
Congratulations on your purchase of the COBB High Flow Catted Downpipes for your N54 BMW
135i/335i! The following instructions will assist you through the installation process. Please read through
all of the instructions first BEFORE beginning the install and familiarize yourself with the steps and tools
needed. If you feel that you cannot properly perform this installation, we HIGHLY recommend you take
the vehicle to a qualified and experienced automotive technician.
Parts List
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(1) Front Downpipe
(1) Rear Downpipe
(2) Gaskets
(4) M8 x 1.25 x 30 Bolts
(4) M8 x 1.25 Hex Nuts
Tools Needed
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Ratchet
Sockets: 8mm, 12mm, 13mm, 14mm
Socket Swivel
Socket Extensions
Box Wrenches: 16mm, 22mm or 7/8”
Large Flathead Screw Driver
Small Flathead Screw Driver
TORX Sockets: T25, E10, E12, E18
Check Engine Light/Trouble Codes Reference
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0041 – O2 Signals Swapped
2C6A – O2 Signals Swapped
2C7F – Rear O2 Bank 2 Too Rich
2C31 – Front O2 Bank 1
2C32 – Front O2 Bank 2
2C6B – Rear O2 System Check
2C6C – Rear O2 Bank 2 System Check
U0428 – Invalid Data Received from Steering Angle Sensor Module
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Removal of Stock Downpipes:
1. Start off by getting the vehicle up on a lift or placing jack stands under the front of the vehicle to get it
up in the air and give you some room to work. Make sure the emergency brake is set firmly and
you’ve blocked the rear wheels if you’re using jack stands.
2. Loosen / remove the stock exhaust. The downpipe installation can be accomplished by just
loosening the stock exhaust, but it is much easier if the exhaust is removed. If you have an
aftermarket exhaust, just the front portion of the exhaust needs to be removed. The exhaust bracket
can be removed with an E10 TORX socket and a 13mm wrench/socket. You will also need a 12mm
socket to remove the 4 x DP flange bolts.
3. Next remove the front underbody panel with an 8mm socket.
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4. Unbolt the steering rack using a 16mm wrench and an E12 TORX socket. The 16mm nut is hidden
on the top side of the steering rack. Next lower and slide the steering rack over to the driver side to
allow for more space to access the downpipes.
5. Remove the steering rack heat shield using the T25 TORX socket. There are three screws that need
to be removed.
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6. Before you remove the front oxygen sensors, it is recommended that you mark them so that you
remember which goes in the front or rear downpipe. Once they are market you can remove the front
oxygen sensors. First remove the front downpipe oxygen sensor with the 22mm or 7/8” wrench. Next
remove the rear oxygen sensor.
CAUTION: Handle the oxygen sensors with care. They can be damaged easily and will cause
error codes.
Remove First
O2 Sensor
Remove Second
O2 Sensor
7. Using the 12mm socket, remove the two bolts that hold the stock downpipes to downpipe bracket.
Copyright © 2012 COBB Tuning Products LLC. All Rights Reserved | www.cobbtuning.com
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8. Unplug the rear oxygen sensors and loosen the wires from the clips. Using one or two small flat head
screw drivers will help you release the tabs that lock the sensors into their connectors.
Front DP O2
sensor wire
is Black
Rear DP O2
sensor wire
is Gray
9. Loosen the v-band clamps on both downpipes using the 13mm socket. Use a screw driver if
necessary to break the v-band clamps loose after the bolts have been removed.
Copyright © 2012 COBB Tuning Products LLC. All Rights Reserved | www.cobbtuning.com
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10. Remove the front downpipe first by snaking it past the subframe.
11. With the front downpipe removed, you will now have enough space to remove the rear downpipe.
12. Remove the downpipe bracket with the E18 TORX socket (14mm socket works as well). The
transmission bolts are aluminum so be careful not to over torque them when putting the bolts back in.
Copyright © 2012 COBB Tuning Products LLC. All Rights Reserved | www.cobbtuning.com
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Copyright © 2012 COBB Tuning Products LLC. All Rights Reserved | www.cobbtuning.com
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13. Remove the rear oxygen sensors with a 22mm or 7/8” wrench.
CAUTION: Handle the oxygen sensors with care. They can be damaged easily and will cause
error codes.
Copyright © 2012 COBB Tuning Products LLC. All Rights Reserved | www.cobbtuning.com
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Installation of COBB N54 High Flow Catted Downpipes:
1. Install the rear oxygen sensors into the COBB Downpipes using the 22mm or 7/8” wrench.
CAUTION: Handle oxygen sensors with care. They can be damaged easily and will cause
error codes. The oxygen sensor with a BLACK wire is for the FRONT DOWNPIPE and the
oxygen sensor with a GRAY wire is for the REAR DOWNPIPE. Switching the front and rear
oxygen sensors will cause error codes. See list for possible codes above.
2. Install the Rear Downpipe by snaking it in between the subframe and the chassis. Secure the
downpipe loosely into v-band clamp using the 13mm socket and bolt but do not fully tighten.
3. Install the Front Downpipe next. Again snake the downpipe between the subframe, rear downpipe
and chassis to install. Secure it loosely into the v-band clamp as well.
4. Plug in the rear oxygen sensor cables. Make sure to double check the oxygen sensor wires such that
they are installed into the correct downpipe. The black O2 sensor goes to the front downpipe and
the gray O2 sensor goes to the rear downpipe.
Copyright © 2012 COBB Tuning Products LLC. All Rights Reserved | www.cobbtuning.com
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5. Install the 4 x bolts and 2 x gaskets. The N54 is sensitive to exhaust leaks here and may trigger
catalytic converter codes if there are leaks. Use the supplied gaskets because the OEM gaskets tend
to break down over time and may leak.
6. Install the exhaust back onto the DP flanges and tighten with the supplied 4 x serrated flange bolts
and a 12mm socket.
7. Once the exhaust is tightened, you can tighten the v-band clamps on the turbos with a 13mm socket.
Copyright © 2012 COBB Tuning Products LLC. All Rights Reserved | www.cobbtuning.com
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8. Install the rear downpipe front, oxygen sensor first using a 22mm or 7/8” wrench. Next install the
front downpipe, front oxygen sensor. You won’t be able to torque down the rear oxygen sensor when
the front oxygen sensor is in place.
CAUTION: Handle the oxygen sensors with care. They can be damaged easily and will cause
error codes. The oxygen sensor with a BLACK wire is for the FRONT DOWNPIPE and the
oxygen sensor with a GRAY wire is for the REAR DOWNPIPE. Switching the front and rear
oxygen sensors will cause error codes. See list for possible codes above.
Install and
tighten front
downpipe O2
sensor second.
Install and
tighten rear
downpipe O2
sensor first.
9. Reinstall the steering rack heat shield with T25 TORX socket.
10. Move the steering rack back into place and bolt it back onto the subframe using a 16mm wrench and
E12 TORX socket.
11. Finally, reinstall the underbody panel using an 8mm socket.
12. Download and/or Install the appropriate Stage2 or Stage2+ FMIC map using your COBB Accessport.
13. Congratulations! You have completed the installation of the COBB Downpipes for your BMW. Go out
and enjoy!
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