P0301 - Misfire Cylinder #1 (now won't start)

[AZ-Ted]

Just got the P0301 code on the way home tonight. Truck started to run rough, and the SES was blinking. I'm parking it until morning, as it's 110*F out right now. Hopefully, it's just the plug and/or coil pack.

[AZ-Ted]

Tried to restart it last night, but it would not start.

[AZ-Ted]

This morning, I changed the plugs using the how-to from CF (big thanks to shinermiller):

http://www.clubfrontier.org/forums/f...rontier-40507/

Spark plugs were overdue (I'm at 120K miles), but they didn't look bad - just old and somewhat worn. I was hoping #1 spark plug (passenger's side front plug) was going to be looking really crappy, but it looked like normal wear:



Truck will not start. Too hot out to mess with this now. In the morning, I'm going to spray some starting fluid down the throttle body to see if that will help (maybe a fuel issue is causing the no start condition).

[masscomguru]

Ted, I would try swapping the coils around to see is a) code changes and b) to see if you can get her to start up. You probably just have a bad coil (cylinder 1)
Free bump for other ideas....
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[AZ-Ted]

Thanks man. I tried the starting fluid. I tried swapping coils. No luck.

The weird thing is the electric fan on the radiator kicks on as soon as I turn the key on (this shouldn't be happening). My fear is that something is wrong with the ECU.

Unfortunately, I'm going to have to give up and have it towed to a repair shop tomorrow.

[AZ-Ted]

No start is due to a bad ECM. Bummer.

[steve500]

Ive seen this a few times on the forums and happened to my 05 Frontier spontaneously.

I still have yet to come down to the cause of this.

Dealer says it was bad ground harnesses on the engine and body that split off from the ground junction connected to the battery.