M50 coils, main relay or fuel pump relay?
When do the coils get their +12v? Is it when the fuel pump relay clicks over or the main relay clicks over? I am wanting to make sure that they come on when the fuel pump relay clicks over because I don't want to have my coils loading if the car isn't running else pop pop pop
When key is turned into run or start.
But I don't see your point!
Javier
Let me rephrase to make it clear. ...
12+ is received from ignition key, not the main relay, nor the pump relay. Main relay feeds, besides ECU, injectors, pump relay, oxygen sensor relay, evaporative purge valve, ICV, EGS, and MAF.
I do agree that having 12 Vdc at one pin of the primary coil does nothing until you get the other pin grounded (unless you have coil issues), that won't happen until ECU decides to do so. Not sure about your special retrofitted ECU, but guess it won't either fire the coils until you get a sync. signal from CPS.
When the cars were build with distributors and contacts, yes you could be in trouble keeping ignition key turned on for long time if the contacts were closed (that happens in more than 50% of the distribution rotation). You may be too young to remember those times! (just kidding).
Javier
About the mod you are proposing. ...
I'm not sure it will be fine, I meant switching the 12V supply to the coils from the key to the pump relay. The pump relay gets a priming pulse when you turn key on, and then stops waiting for CPS/ECU to turn it back on. I don't know details on the criteria to turn it back on. If it requires a minimum rpm that is only achieved when firing gets in, you will end with a non starting engine.
Best solution is to check for this. The coil supply line is a green wire coming from the key switch, and going to all the coils together and the ECU pin 56. You need to keep the feeding to the ECU from the key, so can loose the green wire at splice X6831 (when all coil green wires mets together), and substitute for a wire from fuse F23 (Feed side, by the way coils are unfused). Test for proper starting. You can select to avoid permanent wiring damage testing the pump relay for kick in wile cranking the car without the coils connected. If cranking speed is enough for pump to be energized (sorry I doubt it), you will be fine making the mod. If not, this will confirm my suspicion that if the engine does not kick in, the pump is not energized. May be Bill R. can tell us about the criteria.
If there is a recommendation to control the 12V supply to the coils, may mean that aftermarket ECU is grounding the coils as a steady state condition wile the engine is not running (like old distribution cars). Bad indeed!
Javier
Edit: By the way, may be the aftermarket ECU criteria to turn the pump back on is different to DME, and do it as soon as it sees CPS pulses, them permitting the coils connected to the pump relay to fire up the engine.