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E90/E92/E93 JB4 tune

Why do it

Tools you'll need

• Torx bits
• Socket set
• Phone or laptop for setup
• Socket set
• Phone or laptop for setup

Starting out? See our budget tool list.

Parts to buy

• BMS JB4 tuner (N54) The tuner in our video. Plugs in with no permanent wiring changes.Fits 2007–2013 · 335i (N54), 335xi (N54), 335is
• BMS JB4 tuner (N55) Harness A or B depends on your build date. BMP checks it from your VIN.Fits 2011–2013 · 335i (N55), 335i xDrive (N55)

Double-check fitment before buying. We may earn a commission when you buy through these links, at no extra cost to you.

Steps

1. Open the DME box

   • Remove the cover to reach the engine computer.
   ▶ Watch this step (N54andMore, on a 335is) (1:09–2:39)

2. Install the harness

   • Plug the JB4 harness in between the DME and its connectors.
   ▶ Watch this step (2:39–4:54)

3. Connect the module

   • Connect the module to the harness.
   ▶ Watch this step (4:54–6:46)

4. Tidy the harness

   • Route the wiring so nothing gets pinched, then finish connecting the module.
   ▶ Watch this step (6:46–8:39)▶ Watch the module hookup (8:39–10:36)

5. Close up and set up

   • Close the DME box and set up the app.
   ▶ Watch this step (10:36–12:05)▶ Watch the app setup (12:05–15:24)

6. Plug in the sensors

   • Remove the engine cover and intake, then plug the JB4 harness into the factory sensors.
   ▶ Watch this step (Turboed YL, on an N55 335i) (0:36–2:16)

7. Connect the JB4

   • Tap the remaining wires as the harness instructions show, then connect the Bluetooth adapter.
   ▶ Watch this step (2:16–2:50)

8. Finish up

   • Refit everything, then pick your map in the app.
   ▶ Watch this step (2:50–3:22)

How to know it worked

• No codes after a drive.
• Boost matches your map in the app.
• No codes after a drive.
• Boost matches your map in the app.

Follow your part's instructions and your service manual's torque specs.