I like telling stories, so skip the next couple paragraphs to get to the point...
Starting about September, I left my car in the garage for a week while off traveling for a week, and when I came back and drove to work (3 mile drive) shifter started shaking and my SES blinked a few times. Misfire. I pulled over, turned off the car, turned it back on, and it was fine again. Drove another mile and it started again. Turned off, turned on, it was ok all the way to work. Drove about 8 miles round trip for lunch, no misfires. Drove home, no misfire. Few days later, misfire again, and same solution, no problems for a while.

I had a couple business trips lined up so it seems to happen more often when I drive the first time after a few days of just sitting in the garage. Every time I goto Autozone to scan it, there are no codes and no pending codes. Today while driving, it started misfiring, so luckily I was next to an Autozone and I never turned the car off and had them scan it.

P0301: Cylinder misfire detected - cylinder number 1. FINALLY I know what cylinder it is.

So, around May, 2010 or so, I installed Pacesetter LTs with TSP Y. The rest of the mods are in the sig. I've been lazy to pull the computer for a mailorder tune, but other than actual problems with my spark plug or leaks, etc, could my being lazy to not tune the car for headers & e-cutout have caused this? Do you think if I were to get a tune, the misfire would just go away? Any idea on why the car being off and left alone for a few days would make the misfires happen more frequently?

 

Considering you can do H/C/I and headers all at the same time and not get misfire, I would look elsewhere. Pull the plugs and see how they look?

 

No. And that's not a very good outlook on how to fix a problem.

A misfire is usually either due to an ignition or fuel related problem. This is what you need to do.
-Put a new plug in cyl #1, see if it goes away.
-If that doesn't work, swap wires w/ cyl #1 and 2. See if the misfire moves over to cyl #2. Then you know it's a wire.
-If that doesn't work, swap the coil packs. See if the misfire moves.

More than likely you'll find the problem doing one of those things.

 

After I put my headers on I got a couple of misfires too....Ended up being that I cracked a couple of Spark Plugs going in, they're so delicate, So I got some new plugs and went easy on them. Then I also ended up getting some MSD wires and havent had problems sense. I would say it was easy but changing out spark plugs a couple of times a week in my garage got really annoying....and dangerous, after a week my arms looked like I got into a fight with a cat! lol. God Bless!

 

Check the plugs and wires. Make sure your spark plug wires are not arching to the headers. I had this problem and was getting misfire issues.

 

What do you mean by arching? You mean touching? I put a spark plug wire on the #4 cylinder I think (either 4 or 6) because the EGR port (that's not used only blocked) on the header was touching it, but that's not the one.

Is arching an electrical related issue or heat related?

 

installed headers on my car once and after install it ran like crap.. at wot it would studder and pop so loud it sounded like a gun shot. heres was the problem...




ONE cracked plug...
it would only arch and miss fire under heavy throttle.

do what Damian says... he always has good advise.

Arcing is electrical current jumping across a gap, or creating an arc, as in a spark plug firing, or lightning arcing across the sky, but instead on here they mean its arching in the wrong place.. side of the plug..(cracked plug) or a bad wire.. ect..

 

This...couldn't have said it better myself.

 

Like he said check your plugs.

 

Thanks for the replies everyone! I'll have to check the Cyl 1 plug this weekend. I'll let you know what I find.

 

Sometimes the PCM tells you the wrong cylinder... so also check the spark plugs adjacent to #1 in the firing order (1-8-7-2-6-5-4-3) i.e. check #8 and #3... or check them all.

 

Sigh...I was afraid of that...#8, and now #6 (thanks to Pacesetter's retarded EGR port...when I ordered one WITHOUT it!)

 

Well, I changed my #1 plug, and swapped #1 and #2 wires while I was at it.

I should mention that while these misfires were happening intermittently, I did go to the track a couple times and probably did a total of about 6 runs, obviously at WOT, never had a misfire or any problem there.

Something I am noticing lately, though, and this was before I swapped plugs. Occasionally while just regular driving, and usually in 1st gear, I'm just accelerating from a light (nothing hard, just regular), and there'll be this hesitation around 2000-3500 RPM. It lasts for like a split second and then all is well again. It can happen multiple times in a 5 mile trip, but it only happens occasionally when in first gear and when moving from a stopped position.

Any ideas?