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1.3 Motronic Up-Grade & 2.7i How To

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    If the check light on your dash is not blinking any more, you are missing power to something, and that could be your problem. You will need to find a wiring diagram to see what you are missing.
    Another possibility is that you do not have the green wire on the connector next to the ECU plugged in properly. What year is the harness you purchased?
    -P

    Moosehead Engineering

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      Half of the input pins are getting power, we still need to check the rest. The ECU is a 173, and the harness is the original from my 1986 325. It is the round plug, so we didn't have to do any splicing. I guess I need to find the appropriate wiring diagram. Essentially I need to know which pin(s) aside from the green wire would cause the Check light not to come on.. and no spark or fuel to be delivered
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        86 325 wiring harness with 1.3? The plugs are different, aren't they?
        Wait, now I get it, the body harness is from your car. What I am asking is what year is your engine harness?
        -P

        Moosehead Engineering

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          Sorry, the engine harness is an '89.
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            Is it possible that an '89 harness is mismatched for a 173 ECU?

            Edit: All 55 pins are sending power/signal to the ECU
            Last edited by rcfanatic; 04-16-2009, 02:07 PM.
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              The 89 harness is a proper match for the ECU, but there is an additional plug on that harness that feeds through a few signals like the coded driveaway protection for the OBC and the tach signal, and a couple of others. Your 86 body harness may not plug directly into this, so you may not have plugged it in at all. I know this because my old boss did the e-i swap with a late harness on his 86, and some stuff did not work without rewiring. This is not a problem if you use an 86 engine harness, but that doesn't help you now. Look for a plug near your ECU that is not plugged into anything. There will be 3 or four wires. I am pretty sure there will be a green and a black, and mayhbe a yellow and something else, but I don't have the diagram in front of me. You need to find both the male and female plugs and match up some wire colors, and maybe make your own mating plugs.
              EDIT:
              I looked at your earlier posts and noted that you had already gotten this running previously. If you have joined these wires without the proper plug, then you may just have poor connections. I believe that one of them is the check engine light and I know one is for the tach and one is for the coded driveaway protection. You mentioned that the Check light is not blinking- do you mean the check engine light or the light that is supposed to blink for you to check the brake lights, etc.?
              RE-EDIT:
              Did you have this combination working ever or did you just do the swap and now it does not work. I am a little confused.
              Last edited by mooseheadm5; 04-16-2009, 02:51 PM.
              -P

              Moosehead Engineering

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                Sorry for the confusion. The car hasn't run since the parts have been swapped. The light that doesn't come on is the blinking Check light that requires you to check brakes etc. I have a feeling I was sold a dead ECU, because it's getting power to all of the pins and doing absolutely nothing. It seems like the additional plug you are referring to wouldn't cause the ignition, injection, and check light to stop working. could be wrong though
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                  OK, now we are getting somewhere. THe "Check" light has absolutely nothing to do with the ECU, so forget about it for now.
                  That plug I am talking about can exactly cause the injection and ignition to stop working. That green wire I am referring to is for coded driveaway protection. Without it hooked up, the car will never start. Go look for those plugs and get back. If they are not hooked up, you will never start your car again! I might like to add, again, that they may not plug directly into each other because of the different engine and body harness years, so you may need to make jumpers to test it out. This coded driveaway protection, BTW, is the one wire I did not know about when I did my first engine swap 14 years ago (M30B34 W/ Motronic into E12 530i) and I have never forgotten about it since.
                  -P

                  Moosehead Engineering

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                    Ahh, of course it would keep it from starting. duh, thanks!
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                      I spoke to my mechanic, and he had already connected the driveaway protection :( Also, fyi he said it only affects fuel injection. Just getting a little desperate because I've been out of a car for awhile now and it's my dd. Anyway, thanks again for the feedback
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                        I know that it effects fuel injection. I told you to forget about the check light for now, as it probably has nothing to do with your car not running. Did YOU check that wiring? Your mechanic could have done something wrong, it happens. I am assuming it is still at his shop? If it is then he ought to know how to diagnose no start. If no fuel or spark, then check powers, grounds, jump out main and fuel pump relays, check crank position sensor signal while cranking, etc. I am a BMW mechanic and have done multiple engine swaps, and have not had a problem with one not starting. If you or he do not know how to properly diagnose it, you should find a spare ECU if that is what you think the problem is and try a swap testa
                        -P

                        Moosehead Engineering

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                          Turns out the problem was due to the shielding on one of the crank position sensors. It was slightly exposed and grounding. Now that I have the car back and running it seems to accelerate quite a bit faster, which was a nice surprise. My only gripe is that when accelerating slowly from a stop, the engine will drop to about 250 rpm for a moment when I first open the throttle, which occasionally causes the car to stall out. If I open the throttle a lot straight from an idle, it won't do that. It idles at 750 rpm, which is lower than what it was before (1000), but from what I've read 750 is correct.
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                            Silly question, did you try swapping the crankshaft and plug wire sensor plugs? This is a common screw up since the plugs can be connected to the wrong sensors accidentally.
                            -P

                            Moosehead Engineering

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                              I'll have to check that later this week. Seems like if they were accidentally swapped it would run a lot rougher, if at all? I was thinking it might be a TPS/ICV issue
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                                I was posting without yet having read your response. It would not run at all if you swapped the position sensors.
                                Your idling/tip in problem may be due to a binding AFM or could be a TPS or ICV problem.
                                -P

                                Moosehead Engineering

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