Plug And Play Motronic/Bmw Engines - VEMS wiki www.vems.hu

PlugAndPlayMotronic/BmwEngines (2007-08-14 17:47:47)

BMW engine running with VEMS PNP (motronic55 connector)

Beware that a PNP install can only save you from making a harness, the installer MUST still verify the harness, and also some small modifications needed to have a reasonable setup (with stuff that can be done better than originally, or which was missing completely: eg. WBO2, analog TPS, DIS, boostcontrol, launchcontrol input, shiftlight output, etc...)

It's an M20B25 engine (from BMW 325 IX E30 ~1988), but it seems BMW was pretty consistent with the pinout, not many variations

working [config and tables] for factory injectors (and distributer, driven by ignition channel 3)
We received pinout from a guy who made Econoseal-motronic55 adapter harness earlier, and we verified the unclear points. Nicely several of the main risky pins are same as for the audi (AAN/ADU/ABY and 3B) pinouts, and hopefully there will not be many variations for BMW (with some luck, only 1 variant).
- motronic55-pin3 : fuel pump relay control
- motronic55-pin12: +5V output for sensors
- motronic55-pin27: "ignition" supply (+12V when ignition is on)
- motronic55-pin37: flyback
  - VEMS BMW ECU (since 2007-08) connects motronic55-pin18 (constant +12V) to motronic55-pin37 via a small internal 25A relay switched by motronic55-pin27 (switched +12V) and motronic55-pin14 (GND), just like in case of Audi 3B engine. This was necessary in 2 harnesses we measured (to power the injectors). Could someone confirm that his BMW harness does not provide injector+ either, it's the task of the "motronic" ECU ? Thanx
- motronic55-pin52: TPS Note that we installed a proper TPS (instead of the idle-switch), which needed +5V (available at the MAF)
- as the MAF was sent to the Moon, we made a simple MAT from the cheap [temperature sensor] (==NTC), as a threaded MAT was not available on-site
- beware that the factory coil seems to need rather low dwell (not surprising from a 6cyl distributer setup), rather 2-ish (than 3-ish) msec
  - measure supply current and calculate to be sure
  - or at least decrease the dwell until you experience misfire to see the range: *1.5 dwell means ~ *2.25 energy (=> power, heat) , so be careful!
- there was no idle-air valve on this engine, so we could not test that (part of the orig harness). Tested on econoseal-installs earlier though, so if the documented pins are verified (easy), it should be rather smooth.
- an NA => turbo conversion will also most likely need a few extra signals, like output for BoostControl solenoid
- a distributerless install (like a 3x2 coilpack that is very practical) also needs some extra power outputs (3 power outputs instead of 1)

TODO: more notes

we also found pinout for the 35 pin harness, but yet unverified on real engine (not sure if there is much demand)
- Autodata definitely has the 55 pin motronic (1.3) pinout for the e30 325i which prooved to be correct in my measurements (MembersPage/GergelyLezsak)

Now we also have a tester for the motronic-55 PNP pinout, which is very important when making such boxes, to make it easier to complete an install. As for any PNP or other install, onsite verification of the harness is needed anyway (sometimes these harnesses are rather old, sometimes tweaked, which requires even more attention!).

Idle air controller

Anyone knows

what flyback (low or high voltage) ? The 1-solenoid audi likes low voltage (schottky) and high freq, while BMW likes lower freq and perhaps 6..30V flyback.
- and frequency (iac_speed setting) is optimal for this iac valve ?
maybe PID settings for certain engine ?

Gergely Lezsak made a few engines, he wrote some docs too, thanx :

Tacho output for RPM gauge

seems to require inductive pullup (eg. 100 Ohm * 220uH). Does anyone BMW dash RPM-gauge working from "logiclevel" 0/5V or 0/12V output ?

Which models ?
Does the high-voltage spike of the IGBT output with inductive pullup do any harm to such RPM-gauge input ?