Yet another rb25 misfiring issue

[rps13rb]

So guys, I've been fiddling around with my misfiring issue on my rb25 180sx for quite some time now.

Engine is completely stock with only a FCon VPro 3.1. It was running just fine until 1 of the coilpack decided to shit itself and catch fire burning part of the coilpack harness along the way.

Cut and pulled new wiring, still misfiring on the 3rd cylinder, the same cylinder which the coil burnt. Traced the prob to the ignitor and walaa all was smooth. Let the car idle for a bit and the cylinder decided not to fire again.

Opened up the plugs to confirm if its ignition or fuel and the plugs were flooded. Cleaned it up, fitted it back and its running fine again, but once the engine warmed up again the problem will settle back in.

Tried replacing the stock ECU as I had a spare but no luck with that. Swapped 2 different coilpacks so doubt that's the prob. Also a few other spark plugs.

I did do a spark test and let the engine run till it warmed up. When its cold, sparking seems perfectly fine. However, once warmed up, no sparking whatsoever.

Now I'm betting on the Vpro being the culprit but with no spare to swap out and try with, I would like to seek for your opinions before I go around hunting for a Vpro which will be no easy feat.

Any thoughts?

[topher589]

Have u done a compression test ?
Low compression can result in missfire.

[TwoForDeh]

I had this time issue. It would pull fine and hard when it was cold and start misfiring under boost at operating temperature.

I did 3 things at once to try and fix it so I'm not sure which one exactly it was, but, try replacing your coolant temp sensor first and foremost. The 2 pin one, not the single wire one. The 2 pin CTS goes to the ECU and tells it how rich or lean to make it depending on engine temp. A faulty CTS, especially in Nissans, can cause all sorts of issues.

I also put new spark plugs in. I use NGK BKR7E's gapped to about .28 because of the higher boost I'm running. I'm not sure what boost you're running but that could be playing a part.

Lastly, timing. I retimed the CAS and it ran way better and stopped misfiring at operating temperature. Again, I did all this all at once so I'm not sure which one was the culprit but I'm sure they all were playing the part together.

I'd replace your CTS first, just my opinion.