Ok so heres the deal... in all gears except for 1st, as soon as I hit what seems to be like peak trq/anything over like 15 psi the car will misfire really bad. sounds like a gunshot. if you watch the boost gauge the car actually looses a few pounds of boost and then it flies back up to whatever I have it set at. This all started shortly after I installed a DC downpipe and megan catback... the fitment is poor, and two pieces dont really flange up right. I'm looking to eventually replace this but in the meanwhile help me fix this!
Also, in 4th and 5th theres no popping for this "misfire.." the car shudders and reverberates and loses power. again this is only after like about 18/19 psi, and it is intermittent. i tried turning down my boost controller to like 17ish and i have it at like this sweet spot where it rarely does this.. but im sick of running less than full boost. ill try to get a hold of a camera to expl ain better...

 

Sounds like you either have fouled plugs or the stock intake snorkel problem. Hard to tell without more details and actual rpms. Put in a set of NGK BPR7ES gapped to .026.

The exhaust wouldn't cause this. Even if you had no exhaust, it wouldn't effect the boost and cause misfires.

 

^^ exactly. sounds a lot like plugs. i had the same issue you described, even with your lack of details, and once i did my tune up, ( plug change) it was gone.

 

heres the deal... ive had car for 40k miles.
stock plugs taken out at 15ishthousand..
new ones put in.
when this problem started happening i said to myself hmm maybe the plugs? so i pulled out the ones i had in there and put back in the stockers cus they def. had life on them still.
get this... it seemed to fix the problem.. for a day. then the next day the weather changed and its back to bam bam and shudder. sooo..
i havent actually put in NEW plugs.. why would my plugs be fouled? my exhuast? am i too rich?
man, i really need to get a videocamera to explain what its doing.
it seems like at half throttle 15psi it pulls nice and hard
but full throttle like i lose power and and does that thing.
GRrrr this is frustrating.
So warrtalon what do you think could be causing this?
No CEL's by the way, besides p0420
wouldnt a real misfire throw p0300 or am i mistaken

 

by the way i will dbl check now im taking the car out but im 98% sure the intake is all the way down.

could a innercooler leak or piping leak cause this?

 

Is the car stock? It sounds like fuel cut...

 

oh sorry, no the car is not stock
i have a foam hks drop in, hallman MBC, dc sports downpipe, megan catback.

 

It sounds like you have a leak in your intake piping somewhere, but I would check all of your piping to make sure you don't have any loose clamps.

 

thats the thing i just went through my intake piping trying to tighten all the clamps and they were good... havent done a boost leak test tho

 

it seems when i full throttle it from about 2000-3500/4000 its more likely to do the suddering thing.
higher rpms from a roll when i punch it likes to pop and misfire? like 5000 up
basically when i really open up the throttle it does it

 

You keep explaining exactly what happens when you're blowing out the spark. Don't type another word until you've put in fresh plugs. You asked why/how the plugs would foul...well, plugs don't last forever!! That's just how it is...they are basic, routine maintenance. This may NOT be the problem, but for $8, it's a lot easier to verify than to keep asking on here. Do that first so that we can continue to diagnose. You're most likely to cause a misfire due to plugs when you're at full boost - that's exactly what you keep describing.

 

yes! put a new set in and the problem went away runs sweet and pulls nice and even and boost holds ROCK SOLID! so happy thanks for the help.

 

lol silly kid.. see u listened and it worked...

 

Hrm, ok so... I've had that set of plugs on that fixed it originally for like mayybe 4 k miles now. And now the problems back again in full force.

2 questions:

could running no spark plug cover make them easier to "foul" out?

and could not being tuned cause them to foul?

my car should not be eating plugs in 5k miles.

1 thing: I did however recently switch my drop in for the stock paper filter. could this cause this? i didnt actually restart the battery.. so. yeah. Im gonna restart battery and pull the plugs and peek at them. I will take pics of the plugs... Anyone think ANOTHER new set is in order or should i be looking elsewhere since this reoccurs so often?

 

bump someone please