My quick and dirty compressed air pre-oiler before start up,temporary gas tank,The spaghetti monster, I know it looks unsafe but all wires are tied off and wrapped. I thought I would cut all wire to fit in this stage but I think I'm going to wait until it's all in the car.so the engine is turning over fine but had a hard time getting the main BMW relay to work, it seems there was an unknown to me burglar alarm wire that is the trigger wire #86 on the main relay that needed switched power. Main relay is working now but fuel relay is still being difficult, I have power on the #30 terminal, power on #86 but no power on #87. If I jumper between #86 and #87 the fuel pump works fine. So you say the relay is shot and get another, I've been through 4 now and it's the same thing each time.  There is something I'm not seeing, I'm open to suggestions.here is the diagram of the bmw wires coming from the main connector, some I need and others I don't. I thought I didn't need the burglar alarm wire but was wrong now I'm thinking maybe number 3 Injection signal is needed to trigger the fuel relay.

My brain is mush, get back at it tomorrow.

triple post

i'm excited that this thread has come back to life - very cool! your test setup reminds me of those skids they use to test thrust on rocket engines ;} 

the electronics are such a pain, mainly why i went backwards to carbs because every time i got it right something else would bugger up and i get cross eyed chasing wires... 

yeah I'm getting pretty cross eyed at the moment, I have a few more tests to do and if they don't work I'll be  throwing the whole damn bmw ECU in the garbage and go with a stand alone FI controller. At one point I played around with the idea of putting triple carbs on this engine but was told by a few knowledgeable guys that I would loose quite a bit of power. So I guess it's time that I grow up and learn how to deal with electronics.

Looking good Chris. I wouldn't trim any wires atm. Wait until its in the car. You could tidy it up a bit. Messy wiring adds to the confussion.

Do you have a wiring diagram you can post. The plug configuration diagram doesn't say a lot.

Btw Changing to carbs will be a big job to. You need ignition because it was controlled by the motronic to. Its the Motronic v1.1 it I remember the year 87 correctly which should be a little easier to figure out than a motronic v1.3

The version on this engine is the Motronic1.0 basic, and although it is very basic I just can't get it working.

I tried and tested many things but I'm done with it now. Here is a thread on the process, http://forums.hybridz.org/topic/125547-trying-to-get-the-ecu-to-cooperate/

So instead of spending anymore time and money trying to get 30 yr old electronics to work I'm going to start fresh and in the end I should end up with a much better and more versatile management system that will allow me to tweak some extra power out of the engine, no more 'power chips'.

There seems to be a large and vocal anti-MS group, but what I like about the system with only 2 days of internet cramming on the subject is the incredible support it comes with in the way of forums, lots of experience out there that doesn't mind helping a newbie. Very much like this forum.

Have you tried just shorting all of the relevant relays?  Just to see if the problem is that they're not being actuated.  If it still doesn't work it's probably an ECU issue.

They are not being actuated and it's the ECU that has control. I can get most of the systems working if I power them separately by jumpering around the control wire, it's the ECU that doesn't want to play ball.

I can't remember all the conditions for "pump run", but looking at the diagram I would check the speed sensor. It looks like the motronic 1.0 uses it to give a go signal to the pump.

You might need to search the BMW forums like the "firstfives" and see if you can find something about fuelpump controle.

I have a couple of wiring diagrams for BMW's, but I think they are for 1.1. Ill check tonight.

The speed sensor and reference sensor are identical sensors mounted on the trans bell, both were new 6 yrs ago, both check out with the resistance test as do the cables that connect them to the ECU. Since the speed sensor is the more important of the two I switched them around just to see if it changed anything, no go.

The ECU is not releasing the control ground for the fuel pump/O2 sensor relay, it is also not sending the injector pulses which get their power from the main relay which is working properly.

You are getting power at terminal 30 and 86 with the ignition key on, so thats good. The relay should work fine. If you jump the 86 to the 87, you are supplying the fuel pump with power directly from the ECU. Bad idea. The ECU can't handle the for long.

What you are basically doing is bypassing the relay function. If the realy is not activating and you have replaced it, then it must be the ground wire on terminal 85. Check it with a volt meter to the battery positive. You should read exactly battery voltage. Its that or the relay is busted.

The biggest problem with these systems is ground failure.

 

Some simple checks to do:

1. Check all grounds are clean of corrosion and tight. 

2. Speed sensors. These can cause problems. The two sensors are located on the drivers side of the bellhousing: Top is the speed sensor with black plug and bottom is the reference sensor with grey plug. Mix them up and you can confuse the ECU. Its expecting the speed to see movement first. If they are backwards the ECU with interperate that as very slow and think the engine in not running.

If speed sensor fails, it will go into limp mode. You should be able to start it

If reference sensor fails, it will stop all together.

3. Testing the speed and reference sensors. 

Check the resistance in the sensors by measuring the resistance across the following terminals:

1 & 2:   850 - 1050 ohms

1 & 3:   > 100,000 Ohms

2 & 3:   > 100,000 Ohms

When looking at the sensor and one locating tab is up and the side with two is down. Left is 1 and 3 is right. See jpeg.

 

 

 

 

 

 

 

 

 

You could just run a separate ground for the time being. The ground circuit is complicated by a safety system for if you cash and the engine stops.

Its easy to figure out later, but for now you want to get it running and iron out all the small problems as you go. You can solve this with a second oil switch and an extra relay.