M20 help for my 73 2002

[M20powered2002]

Well after a while I find myself here looking for answers. I prefer my 2002 to have turbocharged e30 power (because I am much younger than my car and like to go fast) and have embarked on quiet the venture. After 9 months I have come pretty far along and I am in need of some serious diagnostic help. I have a m20b25 from a 1992 325ic auto with 80k miles on it (barley broken in by my understanding). I have a getrag 5 speed paired to it with a e21 3.91 LSD (e36 guts). The engine is fitted using custom mounts and sub frame modification. Here is where I stand. Rear mounted e30 battery grounded to rear strut bar with positive lead going to a bus bar in the engine bay. Attached to the bus bar I have the original 2002 power cables, starter cable, additional m20 harness power cable. The full e30 engine harness is connected to the engine, the C101 plug is disconnected because it is not necessary to run any other e30 parts in the car. I am running an external walbro inline fuel pump that is hooked up directly to the fuel relay wire (red/violet on most cars, but green/violet on mine) with ground to the chassis. The car is running the original 525 DME that came with it. I have plugged both the DME and three relays into a manual e30 and it ran/started no problem. I have replaced the blue and brown coolant sensor, CPS, ignition coil, rotor, distributor, HT leads, spark plugs, O2 sensor, and probably more I am forgetting. The car has a replacement AFM that has been placed on a custom bracket. Currently there is NO radiator or fluid hooked up, but I doubt this has anything to do with my problem. There is also no fan on the front of the engine due to space issues. When I turn the key I get power to the ICV (buzzing noise) the ignition coil gets hot, really hot, and when I try to start the car the starter engages and it turns over. I have about 150 PSI in all my cylinders. The fuel pump runs and fuel is reaching the cylinders BUT THERE IS NO SPARK! I have followed the E30 flow chart on the wiki and to the best of my ability, found no issues. I have multimetered the harness side of the DME connector and everything seems to check out fine. I am getting 12v from my batter to where it needs to be. I have grounds on the alternator, oil pan, valve cover, battery, and the brown wires off the harness. I am at a complete loss and in need of help. If there is anything that anyone can think of that would help me fix or figure out the issue I would be extremely grateful. Also if there is anyone in the Bay Area that is willing to come take a look at my setup that has serious knowledge of the engine and could potentially figure out the issue I will provide BEER and food! My car is at my garage in Redwood City, I've got all the metric tools you desire and even space for more cars if I can help anyone in return for their efforts (my car currently occupies the lift, sorry). I will attach a few pictures of my car, but since its electrical, I doubt they will be of any help.

To summarize - 1992 m20b25 325ic auto into 1973 bmw 2002 with getrag 5 speed. ICV buzz, power seems good, turns over, fuel, but no spark.

Please help

[varg]

Pull up the ETM and make sure absolutely everything is hooked up right, down to what would be power at the distribution block and strut tower ground, which are close together on the passenger side of the E30 harness. The coil should not get hot so something isn't right. AFAIK C101 being totally disconnected is a problem. We E30 guys are incredibly spoiled by the ETMs, such complete wiring diagrams are hard if not impossible to find online for many cars.

[M20powered2002]

Thanks for the reply. So in response to that, the ignition coil is getting really hot because ignition is on, but the car isn’t running. So without it sparking, it has no where to release the energy. In short, that’s not a problem, just a sign it’s ready to go. The c101 plug does not need to be connected for this swap. I have power spliced, fuel spliced, oil reading spliced, starter spliced and one other thing I can’t remember off the top of my head. You could be right with me having it wired wrong. A question id like to ask has to to with the auto. So when u swap an auto on an e30 I know the neutral safety switch has to be wired. Since I am doing the swap, is my engine harness going to be different? I know there is a pin at 55 on my harness, so would no signal there be affecting anything? Since I’m wiring the starter to my 2002 ignition and it is bypassing that on the e30, could that cause a problem. Would I still need a safety switch wired because I am using the auto harness? Because my dme doesn’t see that on, could it prevent the start?

[varg]

Thanks for the reply. So in response to that, the ignition coil is getting really hot because ignition is on, but the car isn’t running. So without it sparking, it has no where to release the energy. In short, that’s not a problem, just a sign it’s ready to go.

This is wrong. An ignition coil is an inductive device which is operated by closing the circuit momentarily (this is called dwell time) then breaking the circuit, inducing a high voltage across the secondary winding. The coil receives +12V on one terminal when the ignition is on, but it is not grounded until the ECU ignition coil driver does so during crank/run, there is no current flow if the ECU isn't grounding the coil, and the ECU will not ground the coil unless it detects engine rotation, therefore it should never get hot while the engine is off. The fact that it does indicates a wiring problem or an ECU problem with the former being more likely.

The c101 plug does not need to be connected for this swap. I have power spliced, fuel spliced, oil reading spliced, starter spliced and one other thing I can’t remember off the top of my head. You could be right with me having it wired wrong. A question id like to ask has to to with the auto. So when u swap an auto on an e30 I know the neutral safety switch has to be wired. Since I am doing the swap, is my engine harness going to be different? I know there is a pin at 55 on my harness, so would no signal there be affecting anything? Since I’m wiring the starter to my 2002 ignition and it is bypassing that on the e30, could that cause a problem. Would I still need a safety switch wired because I am using the auto harness? Because my dme doesn’t see that on, could it prevent the start?

Pin 42 on the ECU receives +12V when in park or neutral through C131 in the glove box, see the ETM for wire colors. Being an aftermarket EMS guy, I am not entirely familiar with the stock ECU behavior but I'm guessing this signal is used by the ECU to help regulate idle drop when the transmission is put in gear. If the ECU didn't allow the engine to run without this +12V signal the engine would stop once you took it out of park or neutral.

[M20powered2002]

You are correct about that. I was miss informed. I worked yesterday on some new things. I kind of hot wired the engine separate from the 2002. So I have switches in the engine bay for power and the starter. The car still isn’t starting and someone mentioned that since I am using a 92 harness I may have an issue with the OBC lock. I have power going into the c101 plug on 6 and 7, but still no spark. I understand there is a way to bypass the obc lock but what I’m seeing is solutions with wiring inside the car. Is there a way to bypass it just with the c101 plug by sending extra power somewhere?

[M20powered2002]

So I’ve gone through just about everything and don’t know what’s wrong. My coil is still hot and I’m not getting spark. I don’t believe the issue is in my harness as everything omhs out correctly. When I engage the starter power to my coil drops between 6-4V, what could cause this? I replaced the voltage regulator as a precaution in my alternator, added an additional ground to the chassis (one from block and one from original oil pan location). While my starter does engage and crank the engine well, would a bad solenoid stop the coil from getting enough power during crank?