The 2017-2019 Duramax L5P intake swap is straightforward, but a few details make the difference between a clean install and a bad fit. The stock plate under the factory airbox has to come out or the Banks Ram-Air Intake System will not sit down correctly. The MAF sensor also needs to be transferred and reconnected properly so the truck sees the right air-mass signal. From there, the gain is in the layout: the stock resonator is removed, the enclosed airbox drops into the factory mounting points, and the new intake tube and coupler create a smoother path into the turbo inlet. The coupler has to seat against the tube lip and turbo inlet evenly, with the clamps positioned correctly, or it will not seal the way it should. Get those details right and you end up with a cleaner cold-air intake path, reduced inlet restriction, and a solid fit on the L5P.
This installation covers the Banks Ram-Air intake system for 2017 to 2019 6.6L Duramax turbo-diesel trucks. The job is intended to be straightforward and can be completed with basic hand tools, including a 1/4-inch or 3/8-inch drive ratchet with metric sockets, standard and Phillips screwdrivers, clean shop towels or rags, an 8 mm or 5/16-inch nut driver, and a T20 Torx screwdriver. Before any intake components are removed, the negative terminal on both batteries should be disconnected. Because the mass air flow sensor will be unplugged during the process, disconnecting both batteries helps prevent diagnostic trouble codes from being set.
The stock intake comes apart beginning at the intermediate tube. Using an 8 mm socket, loosen the hose clamps at both ends of that section, then wiggle the tube free and remove it. The MAF sensor connector must then be unplugged from the factory intake tube. The connector uses a red safety clip that locks the release button; pull that red clip outward slightly, depress the button, and disconnect the sensor.
Next, cut the zip tie that secures the MAF sensor wiring together with a coolant line so both can be moved out of the way. The factory airbox itself is not bolted down, so with some careful wiggling it can be lifted out of its mounting area. Clearance is tight, but it will come out.
Under the stock airbox is a metal plate with a large opening in it. That plate is secured by four bolts. Remove all four bolts and keep them, because they will be reused to mount the Banks airbox. The metal plate itself is not reused and can be set aside. This step is important because leaving the plate in place will prevent the new intake from fitting correctly.
With the stock airbox out, remove the MAF sensor from it using the T20 Torx screwdriver. The sensor is then transferred to the Banks intake tube using the new stainless steel Phillips screws supplied with the kit. Blue Loctite is not required by the installation manual, but it may be used if desired to help keep the screws secure.
Before the new airbox is installed, fit the two rubber edge trim pieces supplied with the kit. One goes along the top edge and the other along the fender side. In cold climates, warming the trim slightly with a hair dryer or another safe heat source can make it more pliable, but it should not be overheated or melted. Once each piece is fully seated, trim any excess and butt the ends together for a clean fit.
After the edge trim is installed, lower the Banks airbox into position, making sure any nearby wiring or coolant lines are moved clear. Align the four mounting holes in the airbox with the factory bolt locations and reinstall the four stock bolts removed earlier. The holes should line up accurately, but if needed, start one bolt first and rotate the airbox slightly to bring the remaining holes into alignment.
The next factory component to remove is the stock resonator, which is the part used to quiet the intake system. Remove its retaining bolt with a ratchet and socket, loosen the hose clamp, and wiggle the resonator free. Then loosen both hose clamps on the stock resonator coupling and pull that coupling off as well. It may take some movement to break it loose, but it will come off.
The Banks intake tube is first installed into the filter, and that hose clamp is tightened fully. The filter has an internal ridge that prevents the tube from being inserted too far, so once seated, the tube and filter can be clamped together securely.
Next, install the coupling hose onto the intake tube. The hose must seat against the lip at the end of the tube all the way around and must not slide past that lip. If the coupling is pushed too far onto the tube, the hose clamp will not seat correctly. Position the hose clamp about 1/8 inch from the edge of the hose and make sure it sits evenly rather than at an angle. At this stage, do not fully tighten that clamp; it should remain loose enough to allow the coupling hose to rotate for final alignment once the assembly is on the truck.
With the tube and filter assembled, place the filter into the Banks airbox. The filter should sit approximately 1 inch inside the edge of the airbox. Rotate the intake tube toward the turbo inlet and slide the second hose clamp into place. Using both hands, work the coupling hose onto the turbo inlet until the edge of the hose seats against the edge of the turbo inlet all the way around.
Although the coupling hose has a white printed arrow on it, final fit may require rotating the coupler slightly left or right so it mates properly with both the intake tube and the turbo inlet. Once the coupler is evenly seated on the turbo inlet, tighten the final hose clamp. A simple retention check is recommended: grab the intake tube with both hands and pull firmly. If it does not come loose, the connection is secure.
The last electrical step is to reconnect the MAF sensor. Leaving it unplugged will cause the truck to run very poorly. After the sensor is plugged back in, reconnect the negative terminals on both batteries. At that point, the Banks Ram-Air cold air intake installation is complete, and the truck is ready to be driven.