[samsamdar]

Hey y'all - thought I'd take some pics and give some advice on this install as there's not much on the internet regarding N55 and S55 cars. As we all know, the stock EKP kinda sucks; considering the fact that I am upgrading mine to an ET3 EKP, I wanted to rewire my BM3 FF sensor to the FEM module (this is how they come from ProTuningFreaks nowadays) to avoid splicing and messing with the original BM3 harness. Anyways, here's how I did it:

1. Get your sensor installed on the LPFP tophat or underneath the car. I used the tophat sensor because I still have a stock style LPFP tophat. It is plug'n'play if you're installing on the tophat. If you installed it under the car, find a way to bring the wire harness through the firewall into the interior.

2. Locate the FEM and begin disassembly. For LHD cars, it is located to the right of the passenger side footwell. You're going to need to remove the sidesill which is simply held on with 7 beige clips. Just pull the sidesills up with some force. If you break any of the clips, the replacement PN is super cheap: 51477117532. Also remove the plastic trim immediately below the glovebox (2x 10mm nuts) and finally remove the plastic cover that covers up the FEM by pulling it up. You will now have all the space you need to get the FF harness wired up and tucked out of sight.

3. Remove the second connector from the right. In my US-spec N55 M2, there was no connector on the right spot. You are looking for the white connector. Push the tab in and rotate the locking connector upwards. As you rotate the lock, the entire assembly will come out on it's own.

4. Push outwards on the white tab right next to the black connector. This will release the black connector from the white housing and allow you to slide it out.

5. Replace the original black connector with the BM3 one. Make sure you install it in the same position. Note the markings for pins 1, 18, 19, and 36 on both the OEM and the BM3 connector. This will help ensure you put the new one in correctly. Slide it in until it clicks all the way.

6. Plug the other end of the BM3 blue harness (the one with the pins) into the OEM connector. For this one, you need to make sure that Pin 1 on one connector matches up to pin 18 of the other connector, and so forth. For example, pin 19 of the OEM connector will match up to pin 36 of the BM3 blue connector. It takes a good amount of force to push them together so make sure they're flush.

7. Tuck the wiring away. I placed the blue harness right behind this plastic piece but made sure keep it away from the hole where the plastic cover attaches to. The rest of the harness went underneath the sidesill and was tucked into the carpet out of sight. I then routed it under the rear seat and up to where I have my BM3 controller mounted behind the EKP. Make sure to use zipties to keep it secure and DEFINITELY ziptie it so that the wiring isn't touching the EKP. The EKP WILL melt it lol.

And that's it! You might need to reflash your BM3 map to get the sensor working. Also, make sure to disconnect your battery while working and test your sensor out before putting all the panels backing together.

I've also taken some pics so you can see how easy it is to swap over from the EKP harness to the FEM harness. Just order the FEM harness from PTF, take the 4 screws off the controller, and swap the harness out for the new one. This DIY was definitely more involved than just wiring to the EKP but, to me, it's 100% worth it to avoid anymore headaches with the EKP. Hope this helps if you needed help figuring out how to do the wiring!

[johnung]

A Stage2 EKP from ET3 Design is an excellent choice. But what did you mean by “to avoid splicing and messing with the original BM3 FlexFuel harness”?

[samsamdar]

Originally Posted by johnung

A Stage2 EKP from ET3 Design is an excellent choice. But what did you mean by “to avoid splicing and messing with the original BM3 FlexFuel harness”?

Original BM3 harness goes into the EKP and I didn’t wanna cut it up to wire in the ET3. Also didn’t wanna risk running more voltage thru the BM3 harness as I’m planning to.

[johnung]

Originally Posted by samsamdar

Original BM3 harness goes into the EKP and I didn’t wanna cut it up to wire in the ET3. Also didn’t wanna risk running more voltage thru the BM3 harness as I’m planning to.

Are you planning to upgrade the LPFP to a Walbro 450 or 535? If so, you can special order it from Precision Raceworks with a bulkhead fitting on the top hat that runs the power and ground wires directly to the terminal block on the ET3 Stage2 EKP. This bypasses the faulty pins on the BMW connector making it impossible to scorch/melt the top hat. It will look similar to the attached photo.

I’ll also send you a DM.

[samsamdar]

Originally Posted by johnung

Are you planning to upgrade the LPFP to a Walbro 450 or 535? If so, you can special order it from Precision Raceworks with a bulkhead fitting on the top hat that runs the power and ground wires directly to the terminal block on the ET3 Stage2 EKP. This bypasses the faulty pins on the BMW connector making it impossible to scorch/melt the top hat. It will look similar to the attached photo.

I’ll also send you a DM.

Bruh no way I didn't realize that PR was offering their kit with the bulkhead connectors preinstalled - hopefully they'll let me swap mine out. I JUST recently installed my PR stage 2.5 V2 a month ago lol

[johnung]

Originally Posted by samsamdar

Bruh no way I didn't realize that PR was offering their kit with the bulkhead connectors preinstalled - hopefully they'll let me swap mine out. I JUST recently installed my PR stage 2.5 V2 a month ago lol

When I asked them in the Fall they said that I could de-install my PR pump and ship it to them. They would install the bulkhead straight through wiring for a fee and ship it back.

[samsamdar]

Originally Posted by johnung

When I asked them in the Fall they said that I could de-install my PR pump and ship it to them. They would install the bulkhead straight through wiring for a fee and ship it back.

Was it ever confirmed if the Walboro 535 draws more amperage than the OEM pump? I'm wondering if an upgrade to the bulkhead connectors is even needed if I'm going to keep the stock 20A wiring?

[johnung]

Originally Posted by samsamdar

Was it ever confirmed if the Walboro 535 draws more amperage than the OEM pump? I'm wondering if an upgrade to the bulkhead connectors is even needed if I'm going to keep the stock 20A wiring?

Yes, both the Walbro 450 & 535 definitely draw more amperage from the EKP than the stock LPFP. Attached is the graph on the 535 from the Walbro/TIA website showing that it can draw current up in the 20’s. The stock EKP fails bench tests and shuts down at 18A. That’s at 72°F ambient temperature. The ET3 Stage2 EKP is rated to handle up to 35A.

In fact I just ordered the test equipment to allow me to do a study while I’m driving of exactly how many amps my Walbro/TIA Model 535 is drawing with fuel mixes ranging from 93 Octane up through full E85.

After that I’m hoping to find someone in the area of South Jersey, Central Jersey or Philadelphia & Suburbs areas who has a Walbro 450 installed with bulkhead wiring along with a FlexFuel sensor & FF tune, and an ET3 Stage2 EKP. Then I could use the same equipment to repeat the same study for the Walbro/TIA model 450.

Worst case scenario is for me to ship the equipment (it’s very small) to someone with that exact combination along with photos and instructions of how to run the tests. We’ll see what the results of the Walbro 535 first. Fun stuff!

[mike@x-ph.com]

Thank you for sharing OP