Misfiring
 

So, two days ago, I'm pulling out of a subdivision, and just for first gear my car sputtered and pulled an engine code. Took it straight to Advance and the code reads a misfire in cylinder 5. Drove it a while and it ran fine and the light went off so I just figured maybe bad gas. Tonight on my way home from work, however, it does it again, except now it is sputtering all the time, even at idle. I don't know when the plugs and wires were replaced, but I pulled #5 and it looks okay, and I checked the gap and it read .072. Somewhere I read that it is only supposed to be .060, but I'm not sure if thats right. I don't know why this would be happening all of a sudden, unless the gap has been gradually getting bigger? I'm just hoping it's not a cracked head.
Also, all my gauges read fine, and no white smoke.
Any ideas?
Possible bad plug?

regap your plug down. chances are that its not arcing properly. .072... jeesh.

I run .035-.040 on mine.


also check your wires in the dark with the engine running to see if its arcing anywhere else

I just decided to go with new plugs and wires gapped at .060. Just waiting for the car to cool down now. I'm just glad GM didn't make it a 4 banger, that would've been a rough ride. I just hope it doesn't take too long. I used to have a 3.4 bird and I wouldn't even think about doing plugs and wires on that car.

If you're tearing out the wires might as well make sure your cap and rotor aren't scorched.

From a personal "how could I be that stupid moment" I had some really nice headers on my 3.8L and had the same issue I went a week trouble shooting, buying, replacing...and the whole time my headers melted through my spark plug wire. Luckily AutoZone was good about returns! dont know if you have aftermarket headers on your 3.8L, but if you do thats the #1 reason for misfire. (from personal experience...its happened more than once)

Ok, so I only had time today to do 3 plugs, #5 being one of them. It definitely did nothing. I am thinking it is a fuel problem, because I checked spark and it had a good strong spark. Another thing leading me to believe it is fuel-related is that it seems to run ok in low RPMs with slow acceleration, but when I give it more than 1/4 throttle it starts running all crappy on me. I'm hoping it is something like injectors, but I'm pretty sure they aren't clogged because I have put 2 bottles of cleaner, and seafoamed it all within 10,000 miles. So, maybe this could be an excuse to buy bigger ones?
BTW, is there any way to check if an injector is faulty?

Have you done a leakdown test yet?

No, not yet. I'm going to try to replace the coil first. I asked a good mechanic I know and he says thats pretty likely. If that is a no-go I think I may just take it to a shop instead of dealing with it anymore.

Did you clean the MAF sensor after you seafoamed it? It's something to try that won't cost you anything...:iono:

The reason I'm ruling out MAF is that it is only acting up on one cylinder, and with the MAF, it would screw them all up.
Also, I'm pretty sure it isn't a compression/fuel thing now because it doesn't act up all the time, it is off and on depending on how I accelerate. Plus, as I said earlier, it runs fine when it is cold.
I'm going out right now to change the coil. Hopefully this does the trick.

Yep, it was the coil alright.
I just took it for a drive and it ran like... well I wouldn't say new, because it isn't, but it ran like it did before the coil went bad.
Thanks guys for all the input though.

the reason they are gapped like that for stock is to help with emissions. I woulda gapped yours at least .050 IMHO

Grats on the fix!

congrats on the fix sir.

:clap: I like reading successful fixes. :thumbsup:

Yeah, I just wish they were all that easy.