i just finished doing a sr swap on my 93 240sx. I went to start it and it cranked, would start up(with a real rough idle) for a few seconds and then sputter and die. i checked my spark and only one plug was firing! wtf would cause this...i've checked my wiring and is all good. I have fuel...just no spark on 3 cylinders My harness and ecu were from an automatic sr so i had to change 2 plugs, one was for the TPS(different plug than 5spd) and one plug was originally missing but used a matching plug from a ka and wired it properly. I rewired both plugs according to enjuku and how other 5spd sr's were. I'm pretty sure that's not the problem, enjuku said that they used an auto harness on their racecar. All my connections are good, everything was soldered and heat shrink wrapped. I am running an apexi dc bov but that wouldn't cause it to not spark on 3. I'm leaning towards ignitor chip or ecu. My ecu code is 61 which is the code for auto.'s. I'll go to the place where i got the motor and swap the ecu.

I have brand new ngk plugs, a walboro 255 and a 300zx tt fuel filter(one from autozone) as well

I am definately getting fuel.
What in the hell would cause only one to spark!!!
If timing were off it would still spark right?
Anyone else have this problem??? i want to be done with my swap so i can drive the car around and it just seems like the closer i get to finishing something alse goes wrong.

please help!

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Are the coilpacks good? You can test them with an ohm meter. Possibly ignitor chip???

 

My car was doing the same S$#T when I swapped in the DOHC KA, it wasn't too bad but then got worse and worse, and finally wouldn't start at all just like yours. Turned out I had only installed the screw tha holds the plug into the ecu finger tight, and it backed out and the plug was all loose. Tightened the crap out of it and now no problems since. Either this or your ecu is bad would be my guess as a friend of mine had the same problem and a different ecu fixed it.