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E30 M54 Swap Guide

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    I used a 03 Cobra hydro booster for my brakes and steering. Worked out great.


      Swap MS45 TO MS43 ECU


      [B]M54 E30 Swap


      You should start with a E39 or E53 engine harness. If your engine came from a Z3 or a E46 you really don't want to use this harness as the ebox is on the drivers side behind the strut tower on those cars. On the E39/E53 it is on the passenger side, leaving you ample room to mount the ECU in the factory location for the E30, above the glovebox.

      X6011 is a translucent white 12 pin connector block found in the e-box of the donor vehicle, and is part of the main engine harness.

      X6011 needs to have a wire run from pin 5 (which comes from starter connection 30h) to C101 pin 15. This will provide ground for the K5/K7 unloader relays and enable your power windows/sunroof to work. The starter backfeeds 30h with B+ during starter motor engagement to allow maximum amperage to the starter motor.

      Since the MS43 harness will not have a 20pin diagnostic port you'll want to leave yourself some manner in which to reset the SI lights as they do their thing. Grounding C101 pin 11 then turning the key to accessory will reset the oil service LEDs, leaving it grounded a bit longer will reset the inspection. You can either leave yourself a pigtail under the M42/S14 firewall wiring covers to manually ground out, or you can wire up a diagnostic port exclusively for the use of resetting the SI lamps.

      MS43 ECU controls the fuel pump relay by grounding terminal 85. Either construct your own fuel pump relay setup from the original E30 unit, or use a relay with pigtail removed from a native MS43 car. Wiring is as standard for a 5 pin BOSCH relay. The OE BMW relay is probably a lime green TYCO.

      The primary engine harness requires no real modification and will be used as is. The secondary harness which connects to the chassis, automatic transmission and the rear O2 sensors will be heavily pruned.

      MS43 harness as removed from an automatic E39 530i:

      Automatic wiring and other extra crap removed:

      What you're left with:

      Labeling the C101 while I was figuring out both sides of the wiring:

      I also elected to use my engines original MS45 valve cover with the pencil coils. This requires you to repin the X60005 MS45 ECU connector into the correct wiring for the MS43 ECU. The engine will NOT start if you do not repin, and may even damage the ECU. The power connector on the MS45 coil harness will need to be changed as well so get that from your donor too.

      There is also a pencil coil type harness for MS43 cars that will work without modification if it is from a late run MS43 vehicle. The ETK seems inconclusive about this on the production dates, so I would advise you double check the pinout to make sure of what you have.

      MS43 ECU:

      There is a EWS Delete test file freely available from a user "Daniel F." He has a seriously informative Wiki page on his MS43 musings. Please refer to his page you can find the file(s) there.

      Nothing really needs to be done to the ECU to start the engine and drive the car except having it flashed to remove the EWS protection. Without this the engine simply will not start. It will have a slew of faults stored in short order for communication errors with its buddies it expects to talk to on CAN, but these will not affect drivability. They would set a MIL/CEL but since the output for that is also on CAN the E30 cluster CEL bulb is not going to turn on....

      These are the codes you can expect (perhaps more) with just the basic EWS delete Daniel F flash.:

      This may present a problem to guys in California for example, but it's a non issue for some of us.

      Additionally without modification of the ECU code the lack of a Vehicle Speed Signal will put the engine into a limited performance mode, dropping the fuel cut to 5500rpm or so.

      Mark D'Sylva and Markert Motor Works both offer ready made tunes for the ECU intended for use on non-CAN chassis like an E30 to get you everything you need and none of what you don't.

      Now, if you want to get your MIL/CEL working you're going to need some method of capturing the binary identifier for the MIL trigger. Garry Peterson "gpeterson" on here sells just such a device tailor made for this purpose. It is $250 and can be programmed to your specific desires, as it has additional features as well. It allows for ECU CAN control of a PWM aux fan like found on M54 cars via the factory temperature sensor in the lower radiator hose. It also tells the ECU when the A/C is on to raise the idle, and allows for ECU control of the A/C compressor so the ECU is allowed to make the final decision on when the engage the compressor clutch so that it can switch it off during wide open throttle, engine temperature too high, etc.

      Finally it has one additional output that can be programmed to do any number of functions.

      It looks like this:

      Does that all what i need to change (x6005) i mean or there's another pins too ??
      About the x6011 can you explain it more please ??


        M54 swap

        Nice work Jordan as always! Great write up as well. This is the first time I have read this. I am in the middle of swapping my rebuilt M54 engine with the ESS blower attached into my M3. Its an interesting project.



          m54 swap e30 transmission questions

          So the past few months ive been stock piling parts to do the m54 swap and I recently bought a ZF 5 speed transmission form a 2002 Z3M it also included the driveshaft. I still need to buy the clutch and flywheel but I have been looking into a light wheel flywheel for the m54 and a stage 1 clutch for the z3m tranny. My two questions are; Would a m54 lightweight flywheel work with a aftermarket z3m stage 1 clutch? If they're not compatible then can I use a z3m lightweight flywheel on the m54 with an aftermarket z3m stage 1 clutch. The other question is, Is the z3m driveshaft the correct length to go between the stock e30 lsd and the z3m tranny? Or would I have to do half z3m and half e36 driveshafts?

          m54 lightweight flywheel:


          z3m stage 1 clutch:


            M54 sawp in a 635sci

            Hello folks, I am a newbie and know this is an E30 forum but I am hoping it will work on my planned M54 with a manual into my 1986 635csi, any suggestions?

            Thank you in advance Sirs!