I have had xp iridium spark plugs on my cobalt (stage 2/intake) and have always had misfires according to my interceptors, usually 2-6. I have them gap'd at .40 but should I have em gap'd to something else, I am getting annoyed of seeing the misfires pop up

 

I heard .35 is about right, but I could be wrong.

 

0.035 works the best for the mods you have. My 07' came from the factory gapped at 0.035, and she runs great with my mods.

 

its hard to gap a iridium plug without breaking the iridium tip .. be careful, i gapped my coppers at 35 and i still had misfires, because i am a 60s man

 

get rid of the iridium plugs and get copper ones and try between .034 and .038 i have mine at .038 and it works the best

 

one too many zeros man

0.034-0.038

 

yeah that is what i meant fixed

 

thanks for the help, could any of you link me to what plugs ya got?

 

you should get ngk 1 step colder cant think of the part number off the top of my head

 

BKR7e, gapped to .035 for a 3.0 pulley

 

thanks guys, helps a lot.

whats the best place to get em ya think?

 

ZZperformance.com

 

napa carries them

 

so i got gm stage 2 and injen CAI. i want to go colder. 42lb injectors whats the best plug and gap?

 

GM Stage 2 works best with the stock plugs. You really don't need to go 1-step colder with GM Stage 2.

 

You have backfire's because when you let off of boost valve doesn't open quite as quickly as a turbo, it's normal and happens to be fine for your motor. If the pressure is too great your relief or bypass valve does vent. However the fuel maps still run rich causing backfires, you'll see it in any car running more than 10lbs of boost fairly frequently when you've broken the engine in.

I recommend you adjust your plugs all the same. Iridiums are the zenith of performance, just keep in mind they like big gaps, cold good, but keep in mind might want boost the power available to the plugs...

 

2 - 6??? you only have FOUR Cyldiners....

My interceptor says I have misfires too, but I think
its just reading data wrong. I have no engine light
no codes, no other indication of a misfire.

If I leave my interceptor on to MONITER misfires
it will count them and eventually (14 minuests or so) ill
get a CEL wiht P0300. If I check the codes with my
interceptor I get P0300, but when I check with the
scan gauge i baught at Advanced Auto Parts, I get
PASS No Codes. There is something quirky about
the interceptors and the misefireing.

 

get rid of the xp iridium spark plugs if ur talking about the ones longer than stock size then ur screwed !!! juss get the stock one work really well with GMS2 u donn anything more than that trust me i know i had misfires with the iridium spark plugs and one of the sparkplugs melted and messed up the engine.....

 

you can have more than 4 misfires lol gg.

 

I have to say if you melted the iridiums, there was probably an issue with how your fuel was going, like maybe use premium???? EHH?! NO REGULARS! PLUS IS NOT ENOUGH EITHER!

Also if you really wanna make sure your car is running right, run cleaner thru the injectors and replace the fuel filter, that's about it as long as you keep it maintained, it's really not ganna matter if it backfires on a SC, the type of supercharger we have does it simply because there is no way prevent the boost buildup that comes from valves and throttle bodies being closed on the supercharger. The release valve has to have certain pressure before it vents, and the ECM is dump enough to run fuel to feed the engine for moment even though there is no demand anymore.

Especially notable if you run the car up to 40, then drop it into 2nd and coast...

 

who melted their iridiums?

 

i melted mine :x i'l take pics of the plugs and damage :x

 

guys look at the pics of the head and short block and u'll see what that darn plug did on a stock engine with no mods !!!

https://www.cobaltss.net/forums/parts-66/cobalt-ss-sc-full-engine-lot-stock-parts-some-aftermarket-211981/