I have not had the problem since I replaced the plugs and dried out the cylinder.
Going on about 3000 miles since then and just crossed over 320000.

I'm having the same issue on number 4! I can't seem to figure out why. Turns out the threading was messed up, burnt the spark plug and coil, replaced both, fixed threading with insert, and still misfiring. I then swapped injector 3 with 4 to see if misfire would change cylinders and it didn't. Still get misfire on 4. any ideas?

Same thing here, though no rust. Unless it's from the belt pulleys, aluminum doesn't rust. There is a rusty stripe under my hood above the belts, so that's where it'd be coming from if anywhere. Water happens to cyl 1 because it's the closest to the belts, which throw the water on top. I guess any could be exposed though.

Why are some of you saying it's a head-gasket issue? The head gasket wouldn't put water into the tube, since the gasket is BELOW the head (where the plug is). Even if the valve cover gasket (not the same thing) was leaking, show me where the "water" would be getting in? It's nothing but oil and cams in there. Here's mine:
http://imageshack.us/a/img94/4407/img0240hnv.jpg

Also, why are we talking about gap? The 1NZ-FE suggests pre-gapped Iridium plugs.

Thanks to this forum I fixed it. Thank you all.
 

Hello All,

I wanted to share with you that I had run into the running rough and low end power loss in my 2005 xB. Thanks to you all in this forum:wink: that contributed your solutions to my problem my scion is repaired and running ever so smoothly again. At first noticing the problem while driving in town I was worried at first large costly repair bills here we come.:no: Thanks to this forum I was able to troubleshoot the problem with codes from the computer code reader that Cylinder 1 was misfiring. At first I checked and changed plugs just for good measure and small indications on them needing too. I also changed the coil pack of cylinder 1 and bang that was it. I also ordered 3 other coil packs just to have on hand or should I replace all at once or maybe pairs or just leave it alone? Any recommendations?
Thank you all again for this great forum and the great folks contributing.

Cylinder 1 Misfire
 

My girl friend's XA had the same problem. As background I have 40+ years background in auto repair and a degree in the field. First it is not a head gasket issue, the water is clear or a little dirty but has no coolant smell. After cleaning the spark plug well and having the problem return a few days later, I looked at it in the day light. Rain water (home is Portland, OR) is getting past the opening in the engine cover around the oil cap, my guess is the seal from the cowl to hood is weak, I have sealed the cap to cover area with some clear packing tape to make a water tight tent "Over Troubled Waters". I will test for a couple of weeks and report back. 10 cent fix. Make sure to dry the plug well and not drive the car with the MIL flashing, the miss can hurt the Cat Converter or cause a coil to fail. Enjoy.

Plugs changed, coils good,# 3 still misfiring, next step is to change the injectors and send it for cleaning how do I take it out???

Thank,
Rick

I tried getting someone to clean the injector, until I figured out what a mess and headache it would be finding someone to clean it and how much it would cost. Save yourself a headache and go buy one. Replace the #3 injector and see if it does it again.

As far as how to remove the injector, it would take me forever to type. I used a scion repair Manuel to walk me through it.

Rubber boot
 

My xb was misfiring, turns out the rubber piece that fits on top of the plug had a tear in it. I replaced it ($7.50) and the problem has been completely eliminated.

cylinder 1 blew
 

i'm afraid to ask but my 05 xA made a loud noise while i was driving on the freeway, which made idle like it was going to stall. there was an obvious lost of power and idle was unstable like it was goin to stall. i was still able to drive but at the same was scared. i eventually made it home to discover that my valve cover was cracked. as i removed the cover, i noticed right away that the cyclinder boot blown off and out the spark plug well. my car was making this ticking noise before it blew, i wasnt sure what it was since it was the first time i heard it. as far as i can see, the well seems dry and i don't see oil or coolant. the tip of the spark plus is mangled from the explosion. i use NGK iridium plugs, and noticed the tip and medal flange is now touching but i'm assuming that was caused when it blew. i am lost for words and uncertain what to do next. please help, any advice will be useful. thx in advance.

Check the coil pack!

My 2006 box just had the 3 stooges pop up too, after weeks of telling my mechanic something was wrong. My a/c is out, been out for 2 months, mechanic doesn't know what's wrong, then the transmission has been funky for several weeks, now the lights. Took it to O'Rielly's and coded as cylinder 1 misfire. Bought spark plugs. Hoping this is all that's wrong with my beloved square mobile. Any idea what could be causing my a/c issues? I've replaced the serpentine belt twice. I'm at 140,000

Swap coil pack from another plug to check it. Cylinder 1 sometimes gets water in it from car washes, etc and shorts out. This has happened to me, especially if you have an aftermarket grill. It may be in a sort of limp mode if you have the stooges on. First thing you need is your own code reader so you can check it and more importantly to delete the codes. Buy a cheap 40 dollar one. Not specific on why you replaced the belt. If it broke due to squealing then your compressor is going out.