Hi, my car hunt during idling and when e turbo kick in at 4000rpm, my car jurk all the way till 8000rpm.

My story goes like this. Everything were running smoothly for first 2 days after it was tuned until i have a bit of missfire at 7000rpm. My tuner told me to change all spark plugs and i did what he told me. It was running smoothly again for 2 days and during this 2 days I even had a street race with my friends, everything seem normal but the same problem came back on the 3rd day. The most funny part is, why my car can run smoothly for few days only and the problems come back?

Anyone encounter such problem before? Could it be my tuning problem or some hardware problem? Below are the list of my parts.

Evo 8
-HKS storker 2.1l engine
-HKS 280/280 cams
-HKS 1000cc injector
-HKS fuel rail
-HKS GT3037s (With HKS wastegate)
-HKS 3" exhaust (All the way till muffler)
-HKS Twin power
-NGK Racing plug (But still with stock cables and coils)
-Power FC D-Jetro
-HKS EVC B/C

Rgd.

 

Sounds like one of 3 things to me.
1)plug wire
2)ignition coil pack
3)ignition coil boot

Switch out these parts with a buddys and I'd bet you find your culprit.

 

Im thinking what u thought. Will try it out. Thanks.

Any other pals have any other advise?

 

Buddy, had changed all the 3 items u advised to change but problem still there.
So sad that cant slove my problem...

 

what heat range and gap are the plugs you are running? sounds like the spark may be getting blown out you may need a colder range plug or tighten the gap

 

Im using NGK Racing plug 9. The gap is 0.7mm.
My Tuner had checked the plugs, all 4 plugs are no burn mark.