xB: CEL thrown, P0301 Cylinder 1 Misfire...Solved!
 

Solved for me, at least. Code P0301 can mean several things, but mine was easy. All of a sudden one day the CEL / Trac off / VSC lights came on and the box began shuddering and hesitating between 2000-3000 RPM. Pulled the spark plugs and found this:

http://i15.tinypic.com/30t1lwg.jpg

Normal OBX Iridium spark plug on the left, Cylinder 1's plug on the right. Note the brown burn / corrosion marks by the arrows.
I replaced it with the stock NGK plug and everything worked great! Reset the ECU and went on my way.
Simple fix, and a lesson not to fall for overhyped eBay junk parts.

from the looks of it

looks like obx can't stand the pressure... thats some nasty blow by from the spark plug

mother knows best

stick with genuine toyota parts from now on please>?

It's not the part, it's the car. I had the same CEL, same code, stock plugs.

After arguing with the dealer to fix it (they blamed my intake), they eventually found a corroded spark plug in cylinder 1.

Lots of modded and un-modded xBs have thrown CELs, and this could be part of it.

-THE DON

Just to be on the safe side, when I replaced my wife's plugs (members of the Two Box Club) I used Bosch Platinum. I thought about getting her a genuine TRD intake to keep safe as well, but I trusted my instincts and bought a YDR instead.

I was having problem with a mis fire on cylinder 1. I replaced the plugs and the ignition coil for that cylinder. After that my idle was no longer rough but when i took it for a test drive my acceleration completely when out. Any idea what could be causeing this?

Any new info?
I experienced this today.

3rd time this has happened
 

The first time this happened it was 2 years ago, I have a 2006 Scion xB. I took it to the dealership since it was still WAY under warranty they refused to fix it saying that I dumped fluid down into the coil pack. Really?! I didn't even KNOW how to get to the coil pack, much less at the time what that was. Why would I do that to my own car, my ONLY car?! So I took it home after I had to pay for them to "inspect" my car, and had my uncle look at it who is a mechanic. He doesn't understand why didn't they fix it since it is IMPOSSIBLE for me to have poured any kind of liquid into the coil packs since I didn't even know where they were located under the hood (he showed me), he checked and there was no liquid that they had spoken about, he replaced all the coil packs with new and new Bosch spark plugs. Less than a week later my car did the same exact thing, took it to Autozone for them to tell me what was wrong with it now, same thing, misfire in coil pack #2. Took it to the dealership and again they refused to fix it saying I poured liquid into the coil packs and they pressurized the system to see if there was anything back blowing into them, they said no, and again I had to pay them even though I was CLEARLY within warranty, but still they said I did it to my car. We replaced the coil packs and spark plugs yet again. Now 2 years later I'm getting the same thing. Going to try and just replace the spark plugs and hopefully that repairs the problem instead of dishing out $150 to buy all new coil packs and spark plugs. Pray!:pray:

Make sure you keep the cover over the engine in place. I was running mine without the cover. After replacing the plugs, and installing the engine cover, I have not had the problem again. Check for a water hose that may be spraying under pressure. Also, the water channel for the wipers may have a hole just above that area of the head. Mine only did it when I drove it in the rain. I run my fog light holes open so that may have had something to do with it.