Misfire Code P0302

[Mph]

Hello, I have a Eclipse GSX with a 6-Bolt swap but have came across a misfire in my engine. The engine has about 100 or so miles on it. First time it happened I immediately stopped the car. It was off the next time I started it up. The sedond time I was cruising at 3500 RPM's. Out of no where the CEL comes on and the engine is sounding rough. The idle is crappy, as well the driving part too. Now I have done some research thinking it can be all sorts of things.. from the CAS, to wires, to plugs, etc. However I would still like my own opinions from you repair guys out there. Please help.
Thanks,
Matt

 

[jrohner]

What are your other mods? What ECU are you running? Is your base timing set correctly at 5` advanced?

 

[Mph]

It has a 6 bolt block, 7 bolt head. Cylinders bored .85 over, stage 3 clutch, aluminum flywheel, custom exhaust. Not much done to it that would be causing this. I am very unsure, it was running perfectly. And the ECU is stock. Any ideas? It probably idles at the lowest rpm possible, and just sounds very choppy. From what I read, it sounds like something that has to do with the 1g CAS on a 2g head. And that I would need a DSMlink? I dont know if I want to HAVE to go that way.
Thanks,
Matt



Edit: I did replace the wire on the battery because it was set as speaker wire, cut it off, put new heavy duty wire on there. After I did that, I started to notice weird things happening. Every light in the car would dim dark to light. The actual dim switch for the light cluster completely stopped working. Could that be what caused the misfire?

Edit: Also, I have not touched the base timing.

 

[steele_verus]

Is it a multiple misfire? My old coil pack would start misfiring when the engine warmed up. Test your coils to see if they are within spec.

 

[Mph]

No, it is a cylinder 2 misfire. Pulled code P0302. I changed the wires and plugs, CEL didn't come on for a while. After getting on it for a while the CEL came back. Got home popped the hood and a little smoke from the exhaust manifold cover. I believe that was because of oil getting on it. Not so worried about that.

 

[Mph]

Well since no one wanted to reply back to me, I figured it out on my own. I used a pentionmeter, and it works perfectly.

 

[98yctuner]

Did you ever fix it??

My bad, I should of kept on reading. But i am also having the same problem..

 

[eighth]

i am having the same trouble with that code but my car runs fine just wondering what is a pentionmeter. cel is driving me crazy need it gone

 

[chris grunst]

Im getting the same code with DSMlink i did the 1g motor swap and it just randomly misfires wondering what you did to stop it?

 

[greydelta38]

Try the sparks, obviously, but assuming those are fine, the oxygen sensor could be screwing with the cylinders. Along with the o2 sensor going bad, it could cause one or multiple cylinders to misfire and keep the idle from being steady. A new upstream o2 sensor shouldn't be any more than $70 at Autozone or wherever you get one from, and it's relatively easy to replace.