E12 520/6 to Motronic conversion.

[Sriufke]

Howdy.

Well another m20 carb'd solex 4a1 conversion to Motronic engine management system. However with issues.
Story goes as follows...

Fought the carb setup, and could not find anyone to rebuild the carb locally, (they hear the 4a1 and run away) for half a year and still couldn't get it running. Decided the only road is motronic conversion.
So...some facts before we begin.
Original 1979 102k km m20b20 engine in the e12
Stripped everything carb related (Basically base engine pan/block/head with exhaust manifold)
Bought the motronic injection set off an 1987 e30 320i
DME 0261 200 172 Motronic 1.1? It has 3 lines of pins
All the drive belt and accessory pulleys, wiring, hoses, AFM, ICV, ignition system the whole shebang.
Crank sensor is brand new, however aftermarket.
External fuel pump 3bar wired to original relay.
Cylinder identification sensor - connected plug wire cyl no. 6
No O2 sensor, (should still run on closed loop?)
C101 connected properly.
The wire near dme for activating the Fuel pump temporarily wired to coil. I Mean everything's according to wiring diagram.

Here goes the prob.
Try and start it, it either badly misfires and/or shuts down while trying to hold the throttle
Or it goes haywire and revs to redline basically.
A couple of spark plugs go black 5-6 cyl.

Ideas?:
The DME needs to learn idle? But why would it need to go redline?
Vacuum leak? New gaskets everywhere.
Tried two different dme's and afm's - minimal results.
Leaky injectors?
Lack of o2 sensor fumbles with dme not knowing how to set the fuelling map?
And yes I read Murrans thread. Too bad I can't get in touch with him via the forums.
Inputs welcome cheers haha!

[Jeroen]

Weird! Some first thoughts. The 3-row DME means you only have the combined crank sensor at the front (vibration damper), but does it have the correct position on the damper, and did you fit the E30 damper? Dunno at what cilinder the identification sensor should be, my first guess whould be cyl #1. Lack of 02 sensor should not be an issue, not sure if it has emission control switched on as standard but it should at least run on it.

Some useful info here: https://www.e30zone.net/e30wiki/index.p ... tronic_1.3

[Sriufke]

The sensor position on the Vibration damper is correct. All m20 blocks has the threaded holes for the sensor mount. And yes I pulled the damper off the same engine as the rest of injection sys. related stuff.
However thinking now...any chance the counter on the damper could've been changed in 87 on forwards?

As far as I know now. The dme is motronic 1.3. but the wiring hardware is older (87) ? However everything sits on TDC properly.

Edit 2:
Also the dowel and all them woodruff keys are all there. It certainly can't be 180 degrees off?
Although it's starting to sound like the timing is way off.

[Jeroen]

Well if parts all came from the same running engine that should be ok. Vibration dampers are a bit of a puzzle to me, the earliest Motronic E30 M20's had the dual sensors on the gearbox bell housing, around 1986 that was changed to the combined sensor on the vib dam so you would expect a change by that time, but that is not documented by BMW, the only have a change date late 89 but then it can't be related to Motronic versions.

But yes, the situation you describe also gives me the idea the timing is way off.

[Sriufke]

Timing Set correctly.
Crank on O/T one tooth on point just before the flat part on the balancer counter.
Ignition dizzy thingy facing 1st cyl. Ignition contact.
Camshaft lobes facing down (not pushing on valves) on cam mark.

What else?

Edit:

Probably figured it out.
The EVAP system. There's rubber plug just under throttle body. And it was open all the time, therefore sucking in unmetered air.
Can I just plug it shut, or does it need to vent somewhere via valve that's supposed to be there?

[Jeroen]

I'd start by trying to plug it up, that may have caused a massive vacuum leak

[Sriufke]

Plugged it up. Starts a bit better....Still misfires/detonating and/or goes to high rpm. Also the rev indicator stopped working and won't turnover by key. Putting a wire from starter signal to battery to start it.

[Jeroen]

I'm at a loss here as well. Just two more things come to mind, and then I'm out of ideas for now. I believe the plugs for the idle control valve and the TPS are the same, if that's the case, could they have been switched? TPS functioning correctly?