Alright everyone, here's the situation with as much background info as I can think of.

Over the weekend I was driving around with a friend doing some runs in 3rd from about 3000rpm to around 5800. (I never once hit the rev limiter although the traction control did step in a couple of times when the back end got a little light)

After one of these runs I've picked up a miss that is in the entire rpm range (I haven't gunned it obviously since I noticed the miss) I've pulled each plug wire individually and the car DOES run noticeably worse after pulling each wire, however while checking things out I did notice that one of the wires was toast, so I replaced that one.(On a side note I have been fighting this plug wire burning problem for awhile now, it seems that the LG headers I have on the car, are waaaayyy to close to the wires on the 2 front cylinders of the passenger side and are consistantly ruining the wires, even though I have put 2 cool sox on each wire.)

What do you guys think is causing my miss??

The car has an MTI 347 with approximatley 5000miles since I've installed it (I'm still running the Rotella 15W40 and have changed the oil three times for the break in but will be switching to Mobil 1 now that I'm done the break in period)

Engine details

- Forged bottom end
- Cam is Duration 228 in 232 ex. Lift .588 in .575 ex
- Heads are MTI Stage 2E (Ported LQ9's)
- I have a ECS D1SC running 15Lbs of boost and a meth kit, along with the ECS fuel system.
- The car was tuned at ECS and made 716 RWHP.

The car isn't blowing smoke and is still full of both oil and coolant, and there is no check engine light. (I forgot to check the computer for fault messages, but I'll do so tonight and post if theres anything.)

 

I'd pull and inspect the spark plugs first, then the valve covers and check for a broken spring.

Not much to go without codes.

 

I will, I also forgot to mention that the plugs have about 200 miles on them since I replaced them. ( I had another miss and it ended up being that one of the plugs was cracked.)

 

Hook up a Tech II check it at idle and take it for a drive to data log. Using the Tech II you can see which bank the misfire is on and track it down from there to isolate which cylinder the misfire is occurrying on. You may also have a busted exhaust valve spring. I had one before (dual spring) and it would mis at idle and over the entire rpm band.

I don't have a Tech II, I simply took it to the dealership and offerred to pay the Service Writer $20 if he would help me troubleshoot my misfire...he didn't charge me any money and the Tech II identified the misfire easily.

When I was more of a noob (back in 2000) I installed Stainless Works headers (swaintech coated) on my car with the spark plugs in...I cracked one and it caused a mis....I remember because I burned the **** out of my hand when I reached down to change the plug and couldn't feel any radiant heat (idiot reminder) because the swaintech works so well. I have a kevlar glove now.

 

Check the plugs and their gap. I'm betting you're blowing out spark.

 

Check springs..

 

No codes?? Check your crank sensor plug, engine grounds, replace spark plugs ( because they're it's not worth it to put them back in after inspecting) gapped at .035", do a compression check while your plugs are out, check your injector plugs and coil plugs. Did you put an ohm meter on your wires? If not, do that. Do you have cats? If so, they could be starting to fail. Check and do all the easy stuff first!

 

Well I pulled the codes last night and came up with zilch that would cause a miss.

I got
10 PCM P1431 H fuel gauge (which is for the fuel level)
A6 SCM. B2860 H seat/ wheel position. (I think it's clear)

other than that there was nothing. Does this eliminate anything to you guys?? I'm going to be pulling plugs this weekend, checking the Ohms on the wires and doing a compression test as well.