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Has anyone completely removed the ECU unit when they are running a stripped Nikki carb setup? Attached is the wiring diagram for my 1980 manual trans. I have marked up the wiring schematic showing the parts no longer present after removing the rats nest and other stuff when stripping a Nikki, Other than the A/C control relay and the choke switch magnet it seems that the ECU in not doing much to run the car at this point. I understand the function of the Altitude switch as it pertains to the igniter and I was thinking that this could be disabled for the most part. I was wondering if anyone have had success doing this? My goal is to simplify the controls using the stock igniter and distributor setup.
You will probably need to retain the TPS so the trailing ignition works, maybe.
SAs turned the trailing on and off as part of some scheme, probably to keep the thermal reactor lit. That is why they ran the tach off of the leading.
Also, if you disable the solenoids, ACV, and air pump, you will need to get rid of the thermal reactor. Some of that was there to prevent it from melting down, it ran air from the air pump through a cooling jacket. That is what that weird tiny second exhaust pipe was for, that was the cooling air's exit.
SA exhaust could get HOT. I melted a milk jug into a little wad of plastic by holding it near the tailpipe once!
peejay,
I no longer have the thermal reactor, I am running a stock exhaust manifold from a 1992 (I think). It bolted in place and I retained the rest of the original exhaust system and only needed one custom pipe to the heat exchanger. Blocked off the air pipe at the exchanger and removed the remaining section that ran to the rear of the car. From what I understand the ECM could disable the coil to the trailing plugs to allow the thermal reactor to heat up faster. When at temperature it would then active the coil allowing the plugs to fire. The heat exchanger provides a pre muffler to keep the exhaust sound close to a stock system ( I did not want loud). So far I have not found any information on the igniter input connections and there functions. Maybe I will make a guess and see if it runs after removing the ECM plug and see what is going on with the inputs to the igniter.
You don't need the ECU at all. End of story. You do need to make sure all the bits that might be associated with it are disabled or removed so they don't inadvertently cause a side affect when not engaged. As @peejay said, the whole TR and the air stuff for it will need to be replaced/removed and use a header instead.
t_g_farrell,
Thanks for your input. I reviewed the connections to the igniter as shown in the wiring diagram and I would agree that it is not needed. I believe that disable inputs for the trailing coil switched from high to low (+12 to 0 VDC) for both inputs, so simply disconnecting them should keep the trailing coil active all the time. Do you agree with this? I will verify this by checking the Altitude switch and the number 2 water temp switch contacts. Below is what I think is the basic connections to the igniter.
I know this because my ignition boxed fired itself a long time ago and thats when I built my first version of the TLIDFIS ignition referenced in my signature. The box labeled ignitor in your drawing actually contains the leading and trailing J105 ignitors on one side of the base and on the inside is a circuit board used to cutout the trailing mostly.
T_J,
Thanks for the info. Would you have any pictures of the inside of the igniter box? I am not quite ready to replace the system as you did in your nice write-up. But your diagram is very clear as to what must be done. I would like to find a schematic of the circuit board used to disable the igniter for the trailing coil. Its seems that you can easily get replacement igniters since they are used in may other cars. Presently my systems is working but I suspect that I have a failure condition with high temps. I plan to hard wire the igniters to bypass any disable function to the trailing coil to see if the issue is gone. I will try to trace out the circuit board if I can not find any more info,but I would expect that the information is out there some place.
