2007 Corvette LS2 random misfires after header install (Log included)

[BeauRichardson]

My buddy's 2007 ls2 vette started misifring after we put speed engineering longtubes on it along with the x-pipe kit, he also put on an exhaust as well. We completely removed the rear o2's, and used the extension harness for the front o2's. We have double checked spark plug wires to make sure nothing is burnt and that they are all the way on, and we have also checked to make sure the front o2's are not burned either. Everything visually checks out to be good. I have gone into hp and flashed a new tune on it, only touching the parameters for the rear o2's.
I am currently leaning into a fueling issue, and maybe its running too rich or too lean, but from what i remember from riding in it in the past, this problem did not occur until after the headers were installed. I will post the log down below. I haven't done very much tuning, so reading the logs and fully understanding them is still in progress, but i am eager to learn it jesus tune v2 better but still slightly missing check fueling.hpl

[charcoal03silvy]

Can you actually feel or hear it missing or are you just seeing it show here and there in the scanner? Engine should run fine on the stock tune with headers added. Fuel trims seem to agree side to side pretty well, no major indication of a solid miss like seeing one side's trims take off positive or spike in comparison to the other.

If you're actually feeling/hearing it, check the plugs, wouldn't surprise me to see one that's cracked. Have come across that many times after someone did headers without removing the plugs.

[BeauRichardson]

They can definitely be felt. All the plugs were removed for the install and were inspected for any damage or old age. Granted they are a little old, but they don't show any signs of an actual bad plug. I think the most confusing part of this is the jumping of the misfires. They were jumping back and forth between a few of the cylinders, and in a previous log it was worse, i will post that log as well because i forgot to post itjesus corevette after o2 removal.hpl


Dont mind the spelling of the log file

[edcmat-l1]

It's gonna be plugs or wires.

[BeauRichardson]

also i want to add, it seems most of the misfires happen at or around idle or cruising so low rpm. During acceleration it doesn?t occur, only when cruising or at low rpm

[rabbs88]

It's gonna be plugs or wires.

[blindsquirrel]

All the behaviors you keep listing as if they're reasons why it can't be secondary ignition are exactly the symptoms you get from secondary ignition misfires.

[Alvin]

If you include a WOT pass in a log I can tell you which side but I agree with everyone here.

Its going to be a wire or plug.

You can't use the stock metal heatshields on the plug wires for most headers FYI.

People crack plugs installing them, if one was dropped it can break and you not realize it, wires/boots cannot touch primaries.. etc.

[BeauRichardson]

All the behaviors you keep listing as if they're reasons why it can't be secondary ignition are exactly the symptoms you get from secondary ignition misfires.

i?m not trying to list reasons as to why it isn?t i?m just providing all the information i have.

[BeauRichardson]

If you include a WOT pass in a log I can tell you which side but I agree with everyone here.

Its going to be a wire or plug.

You can't use the stock metal heatshields on the plug wires for most headers FYI.

People crack plugs installing them, if one was dropped it can break and you not realize it, wires/boots cannot touch primaries.. etc.

at this current moment the car can?t do a WOT pass, the trans is on its way out so we?re really just baby?ing it right now. but as soon as the trans is done if this issue still exists after the changing the plugs i?ll get back on here and post a new log.
(this header install was just a little project to make time go by faster until we can get the trans in the shop)

as far as the wires, we put msd?s with socks on it after the install because a few the old wires broke. Now the question is, do those socks protect it in the event that it does touch a primary or will it cause an issue even if it?s just the socks that make contact? That being said, i?m not sure that the socks are or aren?t making contact. I don?t think they have enough slack in them to make contact (at least bare) but maybe the sock added enough diameter to it to touch a primary.

[Alvin]

Absolutely no contact between wire/sock and header. MUST have airgap

I see this weekly.. people bring us cars to tune and have several wires burned or arching cause they thought the socks would be enough.

The MSD's are meant to be bent so you can keep them out of the way. Snap it on the plug and bend the boot so it stays away from everything.

[BeauRichardson]

Absolutely no contact between wire/sock and header. MUST have airgap

I see this weekly.. people bring us cars to tune and have several wires burned or arching cause they thought the socks would be enough.

The MSD's are meant to be bent so you can keep them out of the way. Snap it on the plug and bend the boot so it stays away from everything.

okay awesome. i?ll give this shot and see what happens. i would imagine the same issue would occur if the socks made contact with the actual cylinder head yes?

[edcmat-l1]

Not a fan of the MSD wires at all. Matter of fact every car that comes in with them if there's a misfire issue, they come off, go in the trash and AC Delco wires go on.

I'd sooner make my own custom wires than use MSD wires on an LS engine.

[BeauRichardson]

Not a fan of the MSD wires at all. Matter of fact every car that comes in with them if there's a misfire issue, they come off, go in the trash and AC Delco wires go on.

I'd sooner make my own custom wires than use MSD wires on an LS engine.

well that makes sense then because i had the same issue on my personal car, put brand new plugs in, brand new msd wires, and was never able to get rid of the random misfires until switching to accel which so far seems better

[edcmat-l1]

well that makes sense then because i had the same issue on my personal car, put brand new plugs in, brand new msd wires, and was never able to get rid of the random misfires until switching to accel which so far seems better

I wouldn't use Accel either. AC Delco.

[BeauRichardson]

I wouldn't use Accel either. AC Delco.

we ended up using my stock ac delco?s that i had and the issue actually ended up getting worse. we checked all of the wires to ensure that they were making no contact with the primary?s or the head, only the spark plug and the coils. so we pulled those back out, checked the plugs -all good- and then put the msd back in without the socks so we could make sure nothing was touching, and did see improvement, but still misfires, mostly at idle while in park

[edcmat-l1]

I'd bet you aren't snapping them on good enough. I've seen it countless times even by "pros".