Tune didn't work... This problem is def not tune related.

I'm starting to think it could be my downpipe.

 

or coils... at least try changing the boots! as rpm increase so does spark energy, when it becomes easier to go threw the rubber and ground to engine instead of spark plug is when you get the missfire.

seen itmany many times before just not on cobalts generally... but now your down to just guess work.

 

I'm probably going to end up changing them if the exhaust doesn't do it. but there is 2 reasons why I don't think it's spark related.

FIrst when you get blow out the wideband doesn't read the unburnt gas so you get a lean spike. Second, it doesn't do it at low boost. I can bring it right through the revs at 10-12 psi with no problems.

So, my thought now is that my dinkey downpipe which is 2.5 smash bent with the wg recirced is now able to flow enough air when I am at high boost. And what I'm feeling is the wastegate opening and dunping extra exhaust and crowding up the downpipe.


IDK i'm really just geussing now.

 

yeah, im having wastegate issues myself

 

Well I think I've figured it out. I'm pretty sure the exhaust was just too small. The recirc for the wastegate was to close to the turbo. SO my GUESS was that when I hit full boost the wg was opening causing turbulence in the DP and wicked high egt's. I put on a screamer pipe and the issue seems to be gone for now. I'm going to go to a cutout too with a stock exhaust in the near future as well to help it along a little more.


I figured when it wasn't tune related that the only 2 things mechanically the same from my original turbo build and my current one were the DP and the turbo manifold. I couldn't see how the turbo mani would do that so i was hoping that my DP was just plugging thing up and it seems to be it was.


WHat issues are you having? What WG do you run.

 

Hope you figtured it out JC. thats a wicked car on your hands.

 

i know this is a really old thread but i am turbo swapped and having the exact same issue. only difference is i have a 3in downpipe to a 2.5in catback but my wastegate is external dump. i run the ngk bkr7eix at .28 gap. so if anyone has any ideas let me know

 

get rid of those iriduims and go with the coppers. i'm running 7200 rpm 24psi and a .32 gap with zero issues

 

had coppers. these are my third set of plugs. nothing has made a bit of difference. i have tried autolite 3923, 3922, and ngk bkr7e. all with the same results

 

What does your MAP say? When I was having this issue my map would start to drop turns out it was wastegate diaphragm

 

not sure on the map i have no way to check i only have a interceptor

 

Changed the gaps yet though?

 

yea i have tried from .35 all the way down to .28 with every set of plugs

 

i'd say get some logs and post them