P0300 *gasp* '03 Se-R

[Tyrks]

I've been reading and eliminating possible candidates for weeks. Time for some outside assistance. I want to arm you with the available info. So here we go.

About a year ago on an hour long trip, the engine started to run rough and the SES flashed. Pulled over, pulled the code P0301, and waited 15 mins. Car ran fine.

Months later. Same situation. 3 months ago it started happening more and more often. This time throwing the P0300. Runs around 2200 rpm at highway speeds. Revs up more often uphill. Drops to 700 and shakes when stopped. Slight smell of exhaust in the cab. *adds Berryman's, rolls down the windows and like an idiot, I keep driving* Until one morning, no start.

Let the games begin. All electrical systems crank but the engine won't turn over. Crank sensor replaced. No change. Camshaft sensor replaced. Little to no change. On a whim, shifted 1st and 3rd ignition coil. Almost starts. Replaced all spark plugs. Engine starts and runs rough.

Noticed three sizable cracks in the exhaust manifold. New exhaust manifold and precat. Exhaust smell gone, all other problems remain. Voltmeter test of O2 sensor (white deposits) on car registers .35~ volts and drops to 0 from time to time. Just replaced it and the car runs almost the same.

The increased engine vibration is not quite as strong but still noticable. The exhaust from the muffler is a steady putt-putt and medium smell of gas.

To those of you that stuck around, any help would be greatly appreciated. And the others, sorry for the tirade, lol.

[shortfusemonkey]

im not sure what the code is you have, but that almost seems like the Mass Air Flow sensor. my sentra did very similiar things and that was the problem. im not a mechanic, but i dont know if there is a way to test the MAF?

[Tyrks]

P0300 is random misfire code. I have not checked the MAF. I'll google it and give it a shot.

Also forgot to mention, when the engine is completely cold, it starts and purrs like a kitten (or, you know, a suped up sewing machine). As soon as it starts to warm up, the misfires return.

[shortfusemonkey]

Yeah if I recall correctly mine did the same. Let me know what happens

[Tyrks]

Thanks for the reply. It occured to me that I only tested my coils for spark when starting the engine since that was during the no start. I let my car warm up and start its nonsense. Then started pulling the coil connections one by one. Coil 2 was shorting out when warm. Replaced it and BAM. My mean old 4 banger is running like a champ. Ordeal resolved