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This board makes it easy to install Megasquirt on a BMW with a 55 pin Bosch Motronic ECU. You'll need a donor ECU to supply the case and connector. Build this board and put it in the Motronic case, then connect it to a suitably prepared Megasquirt V3.0 or higher using our relay cable. Once you have that done, all you have left to do is run a MAP line and tune it. Fits these BMW applications: E30 chassis 325i with M20 motor E34 chassis 525i with M20 motor E34 chassis 535i with M30 motor Note that BMW switched to the 55 pin connector as a running change in 1986-1987. If you have a BMW from these transition years, you will need to confirm your ECU type before ordering. Here is the bill of materials for this adapter board. This is currently sold as a bare PCB only. | Component | Quantity | Description | Case | Digi-Key Part Number | | R1 | 1 | 10K potentiometer | W103 | CT94EW103-ND | | R2 | 1 | 50K / 100K potentiometer | W104 | CT94EW104-ND | | R6, R7 | 2 | 22 ohm 1/4 watt resistor | 1/4 watt | 22QBK-ND | R3, R4, R5, R8, R9, R0 (V0.05)
| 5 | 1K 1/4 watt resistor | 1/4 watt | 1.0KQBK-ND | | R10, R11 | 2 | 10K 1/4 watt resistor | 1/4 watt | 10KQBK-ND | | R12 | 1 | 100 ohm 1/4 watt resistor | 1/4 watt | 100QBK-ND | | R13, R14 | 2 | 330 ohm 1/4 watt resistor | 1/4 watt | 330QBK-ND | | R15 | 1 | 4.7K 1/4 watt resistor | 1/4 watt | 4.7KQBK-ND | R24 (V0.05)
| 1 | 10K 1/4 watt resistor
| 1/4 watt
| 10KQBK-ND
| Q1-Q5, Q0 (V0.05)
| 5 | 2N2222A transistor | TO92 | 2N4401-ND *
| | Q6, Q7 | 2 | IRFIZ34N | TO220 | IRFIZ34NPBF-ND | | Ign B, C (optional) | 2 | BIP373 | TO220 | N/A (order here) | Boost (optional)
| 1 | IRLZ44 | TO220 | IRLZ44NPBF-ND | | D1-8 | 8 | 1N4002 | | 1N4002DICT-ND | | U1 | 1 | 37 pin male DB37 connector | Right angle | A32103-ND | U3 (optional)
| 1 | 15 pin male DB15 connector | Right angle | A32096-ND | | (optional) | 1 | 15 pin female DB15 connector | Solder cup | 215FE-ND | * Part number PN2222AD26ZCT-ND also works, but must be installed in a reversed orientation on V0.03 boards. This was fixed on V0.05 boards, but then the 2N4401 must be installed in reversed orientation. The new V0.05 version adds the R24 resistor for tach noise filtering and the R0, Q0 circuit that can be used to control the check engine light. It has a slightly different pinout, too. Pin no.
| Pin name | Function
| | 25 | IAC1A
| Tach Out
| | 27 | IAC1B
| Check Engine light
| | 29 | IAC2A
| IGN C
| | 31 | IAC2B
| IGN B
| | 3 | SPR1
| Boost control
| | 4 | SPR2
| Canister Purge
| | 5 | SPR3
| Spare relay on DB15
| This board also allows mounting a DB15 connector for outputs not present in the stock ECU, such as boost control and wasted spark ignition. Click here for assembly directions for the V0.03. For directions for the updated V0.05, click here . (Microsoft Word DOC files) |
