My project car is a BMW E30 from 1984. In 1996 the car had been rebuilt and got a 325i engine with a TD04 turbo.
Since then it has got some major improvements like limited slip differential, intercooler, water injection, etc.
Engine management remained Motronic 1.3
Now it suffers from the lack of engine control, sometimes knocking sometimes coughing, that's why I'm here, and want to see a GenBoard inside! :)
Current setup
These are engine outlines (and details) before changing anything:
- Engine: M20B25 (325i from ~1987) 2500cc, 6 cyl inline, 12 Valves, SOHC (stock, but lowered compression) [Engine bay(huge pic)]
- Fuel injection: Bosch injectors from E36 325i (part no. 0 280 150 415) maybe 190 cc/min @3.5bars. R=~16 Ohms (high impedance)
- Staging injector: Bosch no. 0 280 170 400. It comes from the jetronic cold start inj. (not a PWM system!), maybe 113 cc/min @3 bars, R=~3 Ohms. Actually switched by ~half throttle pos.
- Adjustable fuel pressure regulator (home made, seems working, no fuel pressure meter altough). See MembersPage/GergelyLezsak/FPR
- Water injection. High pressure pump (headlight washer), unknown injector. Actually switched by ~half throttle pos. See MembersPage/GergelyLezsak/WaterInjection
- Turbo: Mitsubishi TD04-11B (it's a small one from 324d), internal wastegate with stock (direct pressure controlled) mech. actuator arm
- Idle control : stock solenoid, Bosch part no. 0 280 140 524. See MembersPage/GergelyLezsak/IdleControl
- Intake: guess it's stock AFM with direct filter. Factory throttle pos switch (3 state; idle, between and WOT). See MembersPage/GergelyLezsak/TPS
- stock 60-2 VR crank-trigger for Motronic 1.3, stock coil, mechanical distributor (guess no mech. advance), stock sparks. See MembersPage/GergelyLezsak/Trigger
- inductive sensor from ignition cable (cyl. 1?) for cam position(?). See MembersPage/GergelyLezsak/CamPos
- Coolant sensors: Two coolant temp (seems stock) at thermostat housing. See MembersPage/GergelyLezsak/WaterTemp
- 1. (one pinout) shows 120ohms @25c
- 2. (two pins) shows 2.18kohms @25c (this one sounds pretty standard temp sensor)
- More sensors: There's no O2 sensor, and there's no IAT (excepting the one may be included in AFM housing -which has to go either). There will be a WBO2 mounted, I guess. It's a must for sure.
![[Engine bay(huge pic)]](http://quasar.dynaweb.hu/~lezsi/bmw/original/PICT0004engine-bay.JPG){kind=link}
Project plan
Current goal : Achieve maximum power output from current mechanical design with reliability in the long run. Good driveability and fuel economy is also in sight.
Future plan : Additional mechanical improvements possible (larger injectors, big turbo, etc.)
Suggestions
How to start? -I think it's easier to go by little steps. Maybe I try to control EFI first and leave ignition to motronic.
Issues with this configuration:
- I have to share crank VR signal between two computers. There's a ~5V DC signal from the ECU. To share this signal, a series capacitor ("high-pass" filter) is needed so the AC is passed but DC is not. Min. value is 10uF (25V or higher recommended) - easy to mount onboard
- You mean I only have to attach the wire to the signal (f.e. from motronic board), and a place is already exists on GenBoard to filter DC current?
- make sure there is no serious current flowing on the GND connection of the VR sensor (VR-). It is very easy to inject 40..150mV noise that can be problematic at very low RPM (cranking). When two ECUs are connected, the GND easily picks up some noise so special care is needed.
- How to check that? I guess there's a 3 pin plug for this VR sensor because one of them is shielding. I measured ~5V DC on one of them but other two seemed to be connected to GND (in ECU). If i use shielded cable to interconnect motronic to genboard, I may not see electrical interferences, may I? (Staying out of engine bay)
- TPS is also problematic, I need to replace WOT switch with potentiometer, therefore I'll lose acceleration ignition retard - I guess.
- with a good MAP sensor the lack of TPS is bearable. You'll need TPS for a nice boostcontrol though.
- Maybe It'll be left off from the first configuration.
- with a good MAP sensor the lack of TPS is bearable. You'll need TPS for a nice boostcontrol though.
- M18x1.5 mm female thread in exhaust after the turbo would be nice for WBO2
- Something like that will be installed. Is it possible to install (weld?) such a thread with exhaust piping in-car? (place is somewhat clear in my opinion)
- consider ExhaustGasTemp (will be a small appr. 10 mm drill in the exhaust before turbo)
- Is it worth besides the wbo2? I'm not sure the place I could install such a thing, cast iron parts before turbo are hardly weldable.
- get a wastedspark coilpack. Common to use Ford EDIS packs, but Opel or VW might also be an option
- 3 transformers with 2 high-voltage terminals each)
- or get 2 coilpacks if you can only get coilpacks for 4 cyl (there will be a spare)
- If I choose this way, I maybe won't need to feed two ECUs the same time which would be somewhat easier than sharing signals. On the other hand, I run a risk of using random ignition map. Don't know which is better.
Any suggestion is appreciated...
Hello
Már régen rá kellett volna rakni.. :) Ismerem a kocsidat NyÃÂregyházán én is állÃÂtgattam a motronicot de tökéletes soha nem volt. A csörgés mindig megmaradt. Rakjál fel egy nagyobb turbót mert a diesel turbo nem erre való. A csináltatott hf tömités hogy birja ?
István