The other day, I think it was Monday, I decided to seafoam my intake and I threw maybe a quarter can in the gas as well and then change my spark plugs as I know they were due anyways. I had about 3-4 degrees of knock prior under WOT, but since I did the seafoam, I've seen up to 12 degrees and it still hasn't gone away. A little worried, but I don't have time to do anything until I'm back from work on Saturday night. Probably won't do anything until Monday/Tuesday when I have time. I figured I'd try adjusting the gap down to 30 thou.. currently gapped at 35. Was also planning on throwing some high octane fuel in it to see if that'd make it go away beforehand, then do the plug gap, and try resetting the computer(disconnect battery). If all of this fails.. what can I do, or what's going on here? Current plugs are stock delco 41-108's. Car has dp, boost tubing, sri, and a trifecta dual stage tune(both tunes do the same thing). It still runs fine as long as the throttle is below 40-50% max. Any higher than that and I see the Kr go from 3-12 degrees like almost instantly, and the more throttle I give it, the higher the Kr goes to the point where it misfires. Don't really wanna go hard on her, but at first I tried since I've seen her "phantom knock" before.
Idea/suggestions?
Thx in advance.

 

what octane are you running? should be running 91+

 

What octane fuel rating do you normally use?

 

what plugs were used?

 

did you change the plugs? could be a bad one

I ran the stock plugs gapped .030 with 23psi on 93 octane with no issues... the stock plugs are fine with the boost turned up, just gap them a little tighter

 

Only have access to 91 octane here in Canada.. just got home from out of town work. On the way home, I decided to test it out. Once the temps hit 145 F, I tried to give it some throttle and to my surprise no knock at all.. 0. Slowed down to 10 or 15 mph, rev-matched first and then went full throttle, short shifted to 2nd cause it was pullin hard, and once the computer caught up, it pulled even harder in 2nd with again 0 knock. At the light, pulled out and once I hit 2nd gear, I tried again.. temps were 176 now and then it started knocking again.. 3 degrees almost instantly, then 6 b4 i let off.. never did hit full throttle :s
Plugs are Delco 41-108's gapped at .035.
Is it just the gap of stock plugs, or could it be like due for a coolant change(sounds silly I know, but once my oil life is below 50, it also starts to knock; finicky engine), or do I have a fubar sensor of some sort?

 

I wouldnt be beating on the car at those temps to begin with. If the coolant was at 145 then the oil was probly on at like 115. Thats not good for a motor period, especially a vvt motor.

Pull the maf and map sensors. Make sure theyre clean and dry(no oily residue) Then pull the plugs and look for anything abnormal. Is any one cylinder causing the misfire? If so move the coil pack to another plug and see if it follows

 

Old plugs were dirty and corroded with black n brown ****.. they were over a year old. The new ones have been in 1 week as of tomorrow, so I'll check when I get a chance. Either tomorrow or monday. Unfortunately, I don't have HPT either to monitor individual cylinders... otherwise I'd have already done that lol. I'll pull the Maf as well when I start playing with it. Just waiting to see what others say as well b4 I do.

 

It doesn't really seem necessary to seafoam a car that's only a year old. It's a 2010 right?

 

2009 and DI engines get quite dirty in the intake, and since it's been blowing black smoke out the rear pipe for a year or more.. and after further reading on this site.. seemed like a good idea... at 24500 miles now so ya.. there's another guy on here with so much crap on his valves he needs a new engine lol.. so ya.. need I say more?

 

Where did u introduce the seafoam? Booster line?

 

The one that's on this site somewhere.. vacuum line into the intake(maybe 1/3 can) and I put about 1/4 can in the fuel tank.. wouldn't even think about putting it in the oil :s

https://www.cobaltss.net/forums/2-0l...13/index2.html
Pic's halfway down that page

 

New 3787 plugs are in.. knock is alot better but not totally perfect.. running husky 94 now, but it's 10% ethanol and the car always hated that fuel before.. it seems to kinda like it somewhat now, except when it gets under full boost.. after a second or two it makes even more power than b4 and then it knocks 2-3 degrees.. otherwise it's fine at any throttle position. Might hafta get a tuning cable from vince to fine tune it now, but it pulls alot better now than it ever did before lol. Maybe it wants 2 step colder plugs :s

 

1 week old 41-108 plugs gapped to factory specs and up to 12 degrees of knock:
I know the pics are ****.. but it's the only camera I had at the time