I need help figuring out why I have no spark. I fully rebuilt my engine and just got it installed. I was able to start the engine multiple times no issue. I shut it off to read codes (was only an o2 sensor code). Went to start it again and suddenly no spark! I have 12v power from black yellow wire at dizzy, engine cranks, main relay is good, fuel pump comes on and I have full fuel pressure and fuel in cylinders. Tried a new dizzy, dizzy from other car, New coil, still nothing! My sensors have 5volts and the cel does the 2 second check when I key on. The only thing I'm not getting is the icm ground switch from ecu. I've checked the wire for continuity and it is not broken. Power is being sent from icm to yellow green wire on ecu but the ecu is not grounding it when cranking. I don't see any obvious signs of failure inside the ecu. I'm very frustrated and don't want to throw money at this. Could it be the ecu gone bad? It seems like the only answer but confusing since the ecu is working in other ways...HELP!

 

Why not try another "known good" ECU ?

 

It's unfortunately hard to find ecus for em1s around here (ottawa canada). I can purchase a used one if it is the issue. I do have an ecu from my first car, a 2000 civic lx with the d16y7. I am going to swap it in to see if I at least get spark.

 

It is not necessary for the ECU to be an exact match to the one in your EM1... just something to try and start the car. If it starts with another ECU, then you know that you will need to purchase another EM1 ECU because yours is damaged.

 

Okay I ran my tests again today. My ecu does not seem to be the problem. I now have spark at the coil but NOT at the plugs 😖 very strange! I have fuel injector pulse and as stated the coil is now firing but when I hold a spark plug to ground it does not fire and engine doesn't start. I have a brand new cap, rotor, wires, plugs. The heck man

 

I know you have new wires, but I'd really suggest buying a new set of wires/warrantying the ones you have.

 

Alright I tried a different ground for the plugs and I have spark. I have fuel, I can smell it and the plugs are wet. It's just not firing now 🙄🙄🙄. Bad gas maybe? The car has been sitting since about September last year. It has run already but I shut it off after maybe 10 seconds and it didn't start after.

 

Alright, found the issue. My freshly built engine lost compression. Yay. It's reading 125 across the board and only wants to start if I add oil to the cylinders. Absolutely shocked.