E84 X1 35i —> E84 X1 LSx

[Bri.Guy]

I’d say the title pretty much sums it up. It’s not a matter of if, it’s a matter of when. I never thought I would swap into this chassis considering an E46 would be exponentially simpler, but, the E84 has been my daily for a while and I’ve grown extremely fond of it.

The intent is for the interior and exterior to maintain a stock or barely modified look, I.e. Black kidney grilles and apex wheels with some recaro sportster cs seats.

This brings a certain level of complexity to the build when you consider how the systems talk to each other; unfortunately this is also something I know very little about. From doing a little research I believe I will have to run the N55 and LSx ECU in parallel so everything that is connected to the CANbus stays happy..but I don’t know what that would really look like in practice.

How would the N55 ECU operate without any active input signals? I’m sure you could find a way to somehow inject the signals from the LSx ECU such as the tach, A/C request etc. but what about the million other sensors the N55 will be looking for? I imagine my iDrive will be freaking out every time it’s powered on.

Should I just give up hope now of having functioning cruise control? I know they make LSx units for cable throttle bodies (which I figure will be easier to integrate than drive by wire) but I can’t imagine how complex it would be to make the BMW unit control on the column try and command the LSx unit. Maybe some type of arduino converter?

I digress, the whole point of this thread is to:

A) Let everyone know that I will be doing it

And

B) Track the progress

And to a lesser extent

C) Beg for help with the wiring and electronics

The physical swap is easy. At first I toyed with the idea of buying an LCI E90 335i or M3 and swapping the front and rear subframe assemblies which would get rid of my XDrive and open me up to a much larger supply of aftermarket goodies. Everything bolts up and matches perfectly, but, ride height is the killer.

The difference in ride height is manageable when you use the “Rough road” kit that consists of spacers for the front strut mounts and spacers for the rear springs. What kills it is when you factor in that using any kind of aftermarket shock (aka PSS9’s) will bring you to nearly a 3” drop from stock ride height on the X1. That’s not going to work.

I think I’ll stick with the subframe setup (which is the same as the E90 335xi) that I have now. For the front knuckles I’ll gut the CV and cut it off so only the sensor ring remains. The rest is mated to the engine, so it’s a non issue. The small rear diff I’ll swap out with an M3 unit and some DSS axles. That should do just fine.

Anyways, the electronics is what I am lost on. I read that Thaniel is not planning on continuing his research until their is a larger following that is willing to contribute to the data pool. I know there are two completed swaps that have been semi-successful with the wiring..but there are not any details posted up. One of them, by Brintech, confirmed that they were not able to get a 100% solution and things like cruise control did not function.

I suppose an alternative option would be to gut the OEM systems and run a standalone system with an aftermarket cluster. I’d really like to avoid this, but it is an option. If I went this route, would there be a way to keep operation of the wipers, signals, a/c, radio etc?

Any help would be greatly appreciated..and I’ll throw this out there..if anyone can provide a “100% solution” wiring setup I’ll pay well for it.

Thanks guys. - Brian

[Bri.Guy]

Ok so I’m looking into my plan B a little more just in case it ends up going this route.

I like the look of a Holly EFI ECU and harness. I could even use a newer Drive by Wire engine which would be great for tuning and cruise control. They make digital dash clusters that would replace everything with one unit.

The only question would be whether the other systems would be pissed off about running a stand-alone.

Things like the air bags, brake lights, turn signals, headlights, ABS, radio, and Climate Control. I know that they all communicate, but are they dependent on one another?

[Lantz]

It’s really going to take someone diving into each system.

The principle of CAN bus is reducing sensors. If the cluster, hvac and engine all need outside air temp the system can use one sensor and have the three modules communicate over can bus.

Picking something simple off your list, the turn signals, nothing is needed from the ls computer. Things like the tach signal and speed will become more difficult tho.

There are some people on here with threads on can bus modules. I would start digging into those threads.


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[Bri.Guy]

I would start digging into those threads.

Well, I may not need to. I have been talking with Wiring Specialties and they may be able to provide a solution. They have a converter/sim that they developed for the e46 CAN; if it works I wouldn't even need to run the ECU's in parallel.

Fingers crossed. - Brian

[HemlockHK]

I know this is years ago, buy did anything ever become of this?