Okay little back story, sold my LT1 and purchased this ws6 last year(first ls1) and although its been running okay, its been throwing a lovely p300 code. Emissions are coming up here and MD so I figured it was about time to really look at it. Scanned and grabbed 420 and 430 as well as the 300. The car was a bit of a frankencar as far as I was aware, tuned and had a few other bolts on like ls6 heads/intake and headers blah blah, but not done well by any means. The EGR was drilled into the ls6 intake and it leaks. I was planning on using some epoxy to seal that up, hoping that is the main cause of my problems. Checked MAF,and it looks fantastic and the car ran the same plugged in and not. Coilpacks were checked and did a visual plugs and wires(really didn't feel like fully checking them today, will do tomorrow).

Upon finishing today, attempted to drive it a short bit of a full cycle, no SES light but scanned a 507 and noticed the Idle was trying to find its home. I guess my questions are....

1.)I know the 300 is a large pita and quite phantom, but a decent size leak in the EGR to the intake could be the issue if plugs and wires are good?

2.)The 507 I am hoping is due to the vacuum leak, which I didn't have popping up before.

3.)Could the 420 and 430 be bad grounds or 02s, possibly leaky cats, any chance the 300 is spitting the 420/430 as well?

The last part of it that really is strange is the car does not seem to idle rough, sputter or have a loss of power anywhere in the powerband(though I have not really driven it much, nor pulled anything much over 3500)Not to mention I am coming from an LT1 with no mods so anything feels good compared to it.

Any ideas would be awesome, I know its a big list and I should start with the epoxy on the intake to see if that solves the problem, but figured I would get some opinions.

 

Definitely fix any vacuum leaks. You most likely need new cats for the 420 and 430. Are you sure it still has cats? The p0300 can be caused by running lean due to the vacuum leak.

 

First off, if it has an EGR, then it doesn't have an LS6 intake.

P0300 can be a lot of things. Vacuum leak is at the top of the list, so are the coils.

P0420 and P0430 are likely due to it having an offroad pipe and no tune. Lift it up and see if the cats are still there.

507 is likely the IAC valve.

 

Well that is just not true, as I said before it was drilled in to keep the EGR(for whatever reason) and Im debating just deleting EGR and just tuning for the cats. Freeze plug is a hell of lot better than trying to fix the attempted hole.

 

Maybe try the diagnostics forum???

 

Crap, sorry, I tunnel visioned in on the codes and didn't read that part. Yeah, the egr leak is almost definitely causing the random multiple misfire. Freeze plug is likely your best shot, or depending on the damage, you could use Marine Tex.

 

I actually was not aware there was one, first time i've had code questions. Sorry and thanks!

No biggy, and yeah I need to see exactly whats going on, I tried to remove the EGR from the intake and both nuts just spins freely, so thats really nice Hopefully the intake is repairable.

I think the codes were never tuned out for the headers causing the 430/420s. So my choices are:
1.) frost for a tune/code removal
2.) grabbing some o2 simulators for a quick emissions fix. (anyone have experience with any?)