BMW 135i – BMW JB4 Install (N54)

I finally pulled the trigger on JB4 and decided to order the BMS clutch stop at the same time. Both products arrived in a few days and I installed them right away.

When I bought the car, the previous owner told me it had some sort of JB tune that was wired inline with the MAP sensor. After doing some research, I thought he was referring to JB+ which would increase boost an additional 2-5psi for an extra 20HP.

Before I could install JB4, I had to remove the JB+ chip that I thought was in the car. I removed the whole intake assembly but found no trace of the chip. I assumed the previous owner lied about it and continued on with the JB4 installation. Once I popped the ECU box open, I saw wires with electrical tape and some sort of aftermarket box with a toggle switch connected to it.

jb3

Since I was confused, I posted up a few pictures on N54tech and Terry identified it as a really old version of a pin-out JB3 tuner. The toggle switch was in the “off” position, so he advised me to carefully remove the harness and plug the wires back into the factory ECU connectors.

jb3_wires

I called a friend over so I could have an extra set of hands and eyes on the project. I was intimidated at first, but it was a lot easier than I expected and didn’t take very long. Before we knew it, we had everything back to the way it came from the factory!

factory_ecu

At this point I was excited and stopped taking pictures. I plugged the JB4 harnesses in and routed the USB cable through the firewall and into the glovebox. After a lot of wiggling, everything was connected and secure. We put everything back together (including the whole intake) and crossed our fingers.

I grabbed the keys and she started right up. I quickly calibrated the gauges and drove to the gas station. I had it set to the least aggressive map on the way there and could already tell a huge difference. I filled up with about 70% 93 octane and 30% E85, then switched to map 5. After a few 3rd gear pulls, I was amazed. It pulls so hard!

e85_jb4

I never thought a piggyback system could be so smooth and powerful. There are so many options through the steering wheel controls and on my laptop via USB cord. I couldn’t be any happier. Next time the tank is empty, I’ll be filling up with 110 octane and testing out map 7.

Once I knew JB4 worked properly, I went to install the BMS clutch stop. A few minutes later, I had it in and adjusted. What a great driver mod for only $10! No more dead space in the clutch pedal and I can shift quicker as well. I’m very happy with both purchases. Thumbs up to Terry for making great products and offering great support!

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