[Success Story] BMW E28 525E? - Proteus 0.4

[MgFoster]

A few weeks ago I picked up a 1986 BMW E28 to work on with my brother. It was a huge basket case, but my hope was that it would be a quick turn around to have a cheap running and driving beater. Well, it wasn't. Milky oil lead to sheared headbolts and a cracked block, brakes all needed to be done, super sketchy vacuum plumbing and electrical under the hood, and a sheared off core support were a few of the issues we found. Do I ever learn that a $750 purchase price is too good to be true? No.

Most of the mechanical journey including engine rebuild is documented here by my brother:
https://grassrootsmotorsports.com/forum/build-projects-and-project-cars/my-first-project-e28/175813/page1/
Here's a beauty shot of the mostly assembled engine:

EngineStand.jpg

We also installed a stage 2 fleabay clutch for future proofing. (read: turbo build)

As if we didn't have enough on our plate, mck1117 is a bad influence, and I was very interested in the Proteus board he had pioneered. I had a good time with Frankenso with my Miata, but assembling the entire board from a bare pcb left a bad taste in my mouth. China assembled boards was very intriguing to say the least.

Thankfully, Frankenso had prepared me for the worst, and the Proteus install was very easy. We had a harness building party, and got most stuff figured out right the first time. We boldly decided to loom and harness tape the whole thing before any testing. Of course I regret this already, but its not too bad.

HarnessBuild.jpg

Harness Tape.jpg

Proteus.jpg

I found this wonderful wiring manual that should apply to anyone with an m20 ETA powered E28.
https://www.armchair.mb.ca/~dave/BMW/e28/e28_86.pdf\

And here's a better way to read the Motronic 1 ECU Connector:

pinout.JPG

I made this nice harness conversion sheet as well, tells you where each pin on the Motronic goes into the ecu connector. Onother thing to keep in mind is that the early motronic had a separate Idle Control Module mounted above the ECU. So some of the wires needed for ICV and such are in that connector.
https://docs.google.com/spreadsheets/d/1drACxoxZc1nh27ujdlHHsznhyMCM_hdU_PnyuTxqRew/edit?usp=sharing

I drilled an tapped the intake manifold to take this nice Bosch TMAP sensor 0261230042. Pinout for it is at the botom of the spreadsheet as well as the sensor data.

BoschTmap.jpg

MAP Data
0.4V 20kpa
4.65V 250kpa

IAT Data
-40 45,313
0 5,896
20 2500
40 1,175
60 596
100 187
150 57

For the TPS, Simon clued me in on the M50 TPS conversion. It has the same 3 pin plug as the original TPS and fits on the throttle body shaft, but needs to be fabricobbled to fit as well as the pinout changed, also on the bottom of my spreadsheet.

FabricobbledTPS.jpg

And that brings us to now, the car runs.
https://www.youtube.com/watch?v=REoBclacpko
https://www.youtube.com/watch?v=8GElfMUwuD8

But wait, it wasn't THAT easy.
We got it to run, barely, using the factory BMW coil and a GM Ignition Module (igniter). On the 2nd startup attempt the module released the magic white smoke. I am not sure if this was from abuse trying to run it on a push pull output instead of a lowside, or what.

We decided to get crafty and try replacing the igniter and factory coil with a single LS coil and still use the dizzy. Remember how I said I regret taping the harness? Yeah, we ran another 2 wires to the ecu for the ign input and signal ground, gave the coil 12V and chassis ground, and BAM. She runs beautifully. Ermmm, beautifully at 2000rpm because we cant get the old 2 pin ICV to shut all the way.

So rocking an LS coil, and no ICV, the car is running quite well. Last hurdle is getting the tacho to work, but I think we have a fix for that.
I will keep my harness spreadsheet updated, and the tune updated on rusefi.com/online as we work through all this. Thanks to all the help from everybody on the slack, this has been relatively painless and I can't wait to get tuning!

[AndreyB]

Thank you for a detailed success story! Please post that content at GRM?

Added to https://github.com/rusefi/rusefi/wiki/Success-stories

[MgFoster]

@russianGRM thread will be updated with RusEFI content soon! Must show them the way.