plz help skyline breaking down

i need help my skyline rb25 is breaking down under high rpm ( 4000 5000 rpm) have replaced dist. assy and allso one coil pack has made slite dif but is still breaking down. adjustad dis. assy made breaking down falt go away however now is pinging / knockt dis back to rectify the pinging but now is starting to break down again, any ideas or info in regards to testing/fixing

"dist. assy"? que? What have you replaced?

Also other details would help: is it standard/modified? esp. boost level?

i need help my skyline rb25 is breaking down under high rpm ( 4000 5000 rpm) have replaced dist. assy and allso one coil pack has made slite dif but is still breaking down. adjustad dis. assy made breaking down falt go away however now is pinging / knockt dis back to rectify the pinging but now is starting to break down again, any ideas or info in regards to testing/fixing

assy = assembly dist/dis= distributer dif= difference

The skyline you are refering to doesn't have a Distributor for one thing. It does have a crank angle sensor, igniter (pre-96), and coil packs.

I'm begining to have the same thing only under high boost, dropping a cylinder completely at times. It is turning out to be a coil pack. It is a common fault on RB motors.

i changed all of the spark plugs and the car is running fine now... thenx for all ur help