VEMS ECU with motronic(88 or 55pin) are available for many BMW engines (harnesses).
VEMS ECU (EC36+EC18 connectors) can also control any spark ignition engine (for lower price, and very good "versatility").
- Usually chosen if throttles and idle are CAN-controlled ([S65, S68])
- or significant modifications are planned
- or factory harness condition is questionable (or bad)
- or if space is extremely tight: Al case is 100mm long for the EC36+EC18 version, 111mm (11mm longer, usually no big deal) for the motronic connector versions
BMW "engines" (harnesses) with 88 pin motronic connector (eg. M50-vanos, M50-nonvanos, S50 and M52 ...) have reasonable pinouts, eg 6 injectors, 6 ignition, ... , also the harnesses are often in good condition, so the [motronic88] versions are often used.
88 pin connectors have slight mechanical variations, see BmwMotronicConnectorVariants
BMW engine running with VEMS PNP (motronic55 connector)
The old motronic55 connector "engines" (harnesses) are designed with only 2 injector pins (3 injectors connected in parallel)
- probably too much or too little weed at the time of design.
- Most installers choose standard (EC36+EC18) VEMS ECU instead of the motronic-55 BMW 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)
- pinout at the [same place]
- 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)
WBO2 on SSC5 male standard pinout (same as audi AAN and 3B):
- pin1 nernst,WBO2 pin 1
- pin2 WBO2 pin 3 (use a 5A fuse from +12V supply wire)
- pin3 heater(-),WBO2 pin 4
- pin4 pump(-),WBO2 pin 5
- pin5 pump(+),WBO2 pin 6
- default: BMW motronic pin 44
- or through endplate if you request so in order note
You can find it in the MAF connector AMP-5 (or 6?) pin female connector.
The pin measures appr 2kOhm vs ground.
(other signals on the same connector:
- ground measures appr 0Ohm vs ground.)
- MAF signal
BMW ECU extra connector pinout:
- pin1 mcp3208 pin6,ch5
- pin2 mcp3208 pin7,ch6
- pin3 mcp3208 pin8,ch7
- pin4 EC36 pin 10 (power out)
- pin5 EC36 pin 24 (power out)
- pin6 GND
- 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!).
BMW changes 2008-04-25
- BMWpin6 tachout (ec36pin10 =>) Ec36pin4 p259/0 (1k pullup)
- BMWpin4 iac2 (EC36pin ??) => EC18pin10 stepperB
- BMWpin22 iac1 (ec36pin6) => EC18pin4 stepperA
- BMWpin1 ignout => EC36pin34,36 (ignch2,3) so ign_dualout can be used to share load between 2 IGBT
tach_channel=07 iac_sol_channel=36 ign_out=72
More changes 2008-05-04
- BMWpin53 +5V (same as BMWpin12)
- BMWpin36 pulling to ground (via EC36-08 inj-C=mask4) activates main relay. Should we turn on exactly at the same time as fuelpump ? Or always (say, misc2out_channel or fan_channel or water_pump_channel ?)
- BMWpin3 pulling to ground EC36/18 inj-F = mask 32 activates fuelpump, no change there. Could be controlled from different or same injgroup (as mask4)
- The internal "3B relay" is dropped. Earlier we supplied power to BMWpin37 injector_common_supply (from BMWpin18 that is node30 battery+) via an internal relay. Nickname is "3B relay" because a similar relay is used in audi 3B. This is not needed any more, as pulling BMWpin36 to ground activates the main relay, and supplies power to injectors.
h=01 02 04 00 00 20 00 00 fuelpump_channel=50 misc2out_minrpm=00 misc2out_maxrpm=FF misc2out_mintps=00 misc2out_maxtps=FF misc2out_minmap=00 misc2out_maxmap=FF misc2out_channel=20
Idle air controller
- 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 ?
- for dual solenoid IAC (mostly BMWs from the '80s) ~100Hz is fine which is config setting value '6'
- for two generation younger, double-solenoid IACs (from '97?) installed in the throttle body I measured 100Hz from stock controller also, however it was oscillating badly with vems at that freq. so I ended up using max speed of '0' (~2kHz?) which seems fine.
- generations in-between (early/middle of '90s) used one-solenoid valve (two pin connector) with spring preset open position, probably similar to audi units? These need totally different control.
- 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 ?
- older BMW series 3 (E21, E30, E36) and series 5 (E12, E28, E34) are just fine with resistive pullup.
- Does the high-voltage spike of the IGBT output with inductive pullup do any harm to such RPM-gauge input ?
Switch TPS to Variable TPS
The BMW Motronic 1.3/1.0/1.1 TPS connector is the same as the variable TPS ones, the Motronic 1.1 or 1.3 TPS wires all go directly to the Motronic connector, Thus no wire changes are actually needed. And any 5V supply , ground and return signal
can be done within the case.
Do you happen to know which motronic55 pins connect to the variable TPS when a variable TPS is hooked up ?
- ground: pin 14,19, etc...
- +5V: (is it pin12 that provides +5V to MAF, or is it a different pin for the TPS?)
- TPS signal: ...
Closed Throttle Input #52
Wide Open Throttle Input #53
Ground goes to common ground S701
- 53 or #52 are 5v and Signal when used with a variable tps,
Do you know part numbers for the variable TPS?
E36 BMW one for instance
I guess it's not mechanically (or even pinwise?) compatible with the [certain Bosch TPS]
opinions from Emil:
It is not worth to invest time into these bmw units, as almost everything has to be rewired anyway
injectors are driven 3 at a time, to upgrade injectors its recommended to use one at a time. Also the TPS thingy, WBO2, air temp etc. Will end up into a harness explosion (yes, i have tried, built a pnp for these cars 2 years ago or so..
You will need to route multiple wires from ecu anyway, which will be more time consuming than building a custom harness.
I think the time rather should be invested in getting it working for the E36 and E34, 24 valve engines which already have the features we need in the harness.
Agreed, time would be better spent into building complete harnesses for these cars. Where all the new items would be incorparated and allow 100% use of the stock C101 connector.