Deck Plate
installed on a 3rd gen gen 4Runner

Jacksonpt shows you how he did the deck plate mod to increase air flow into the engine.

This mod gained popularity with the Tacoma folks, and quickly spread to 4Runner owners. It's a cheap, easy way to gain a little extra performance. Dyno tests show about 7hp from this mod, but I can't personally attest to that (never had my rig on the dyno).

Remove the EFI fuse from the fuse box located behind the battery. Remove the small, 15amp fuse, not the large one. Remove the airbox by removing the 3 bolts holding the airbox in place


Remove the 2 bolts holding the mass air flow sensor in place. loosen the large clamp by loosening a small bolt.


Remove the hose and mass air flow sensor from the airbox. Remove the small hose by loosening the clamp and sliding it down the hose. Separate the airbox from the small intake hose over the passenger side tire. Then remove the airbox.

Next, trace the inner and outer edge of the opening on the deckplate.
You will use this as your guide for cutting the hole


Optional: when you cut the hole, plastic shavings will go everywhere, including inside your airbox. The last thing you want to happen is for those shavings to end up in your engine. I highly recommend lining your airbox with something to catch the shavings. I used kitchen plastic wrap. Aluminum foil would probably work to:


Cut the hole. It would be well worth your time an the little bit of money to buy a 4.25" hole saw. I used a Dremmel and a jigsaw. It worked, but it was a pain. For a good, snug fit, start cutting at the inner circle and trim as necessary until the deckplate fits. For the impatient (like me) cut the outside circle.

Dry fit the deckplate making sure it fits well, and screw holes have airbox behind them. remove the deckplate and run a bead of caulk around the deckplate to make a water-tight seal with the airbox:

Put the deckplate back in the hole you cut in the airbox. Make sure its snug, and the caulk has formed a good seal

Screw the deckplate into the airbox. standard sheetmetal screws will work just fine, just make sure the heads won't pass through the holes in the deckplate. I used spare screws I had laying around my garage.

Once the deckplate is secured, and the caulk has had a few minutes to dry, replace the airbox. Be sure to replace the 2 bolts for the mass air flow sensor, the small hose, the large hose, and the 3 bolts that hold the airbox in place. Make sure the airbox is properly fitted with the intake above the passenger side tire.

Replace the EFI fuse

You should have something that looks like this:


Note: because of the windshield wiper fluid filler tube, many people have offset the hole to the upper left hand corner. This makes it easier to screw the deckplate on and off