Car jerks hard at high boost, need help

[Parsalian05]

first off, my car, as of now, has all of the stage 1 mods done, evo 16g, 2.5in exhaust, ported everything, walbro 190 rewired, bov, ic piping etc.

up until just recently, my car had all the stage 1 mods except exhaust/port work done to it. ever since my evo 16g was put in, the car would jerk HARD out of gear when i was boosting 17-18psi, so i turned it down to about 16psi and it would be fine. after exhaust and porting, i can now only boost 13-14 safely without the car jerking in wot.

after searching threads i wanna say its fuel cut... but ive had that before and it never made the car jerk like it is now, it only made the rpms hit a wall.

also, the car has been idling really low (since the new turbo), and after i would go hard, the rpms would drop so much that the car would often shut off!

if anyone has any ideas, i would really appreciate it.

-nate

 

[yoshimitsuspeed]

Have you done a boost leak test?
What injectors are you using?

 

[out there]

too rich?

 

[Parsalian05]

im on stock injectors, according to the stage 1 mod list, all i need for fuel is a bigger fuel pump, not injectors/afc yet (although theyre next on my list ). as for a boost leak test, i havent actually done it, ill do that today though. ive had boost leaks before, but they never caused the car to jerk violently like it is now.

could it possibly be my spark gap? maybe i need to change it because of more power?

-nate

 

[out there]

:d'oh: you're probably misfiring, perhaps some new plugs and wires are in your future?

 

[dave99gst]

plugs - plug gap - wires

 

[Parsalian05]

thats possible, although i have colder ngk plugs and 8.5mm magnecore wires, ill check the gaps, its .030 for stock right? someone told me to go down to .025-.028 if i get more power though...

 

[out there]

i believe it's supposed to be roughly .28 stock. .3 should be ok, my last set was like... upper .3x and it still ran ok, silly old owner

how often do you come to fargo? we have a nice dsm place here www.straightlinespecialties.com
next time you're in town you should check them out

 

[Parsalian05]

heh i actually come to fargo a couple times a year, i have family up there. ill be sure to check it out. there arent too many dsm specific shops around here (surprisingly).

i didnt have time to do much today but ill be sure to post once i figure out how to fix it

-nate

 

[Endz0r]

fuel cut or boost leak is my guess.

 

[Necromancer69]

Unfortunately i had the same issue you're dealing with. My easy fix was a new set of NGK BPR7ES spark plugs gapped to .28. No more WOT studdering at 23 pounds ;-)

 

[Parsalian05]

hmm, the thing is, its not a studder, its more like ... 1psi, 3psi, 8psi, 11psi, 12psi BANG! and the car rocks like its been rear ended by a semi

anyone ever had this?

 

[td06hkiko]

hmm, the thing is, its not a studder, its more like ... 1psi, 3psi, 8psi, 11psi, 12psi BANG! and the car rocks like its been rear ended by a semi

anyone ever had this?

Looks like fuel cut. You probably need bigger injectors.

 

[Parsalian05]

Looks like fuel cut. You probably need bigger injectors.

you're probably right, 550's and safc are next on my list, but how did i go from running 17psi safely to barely being able to run 10? granted... this is from totally stock exhaust to full 2.5inch turbo back w/ high flow cat and ported turbo/mani/02.