not produceing power at top end

[S73R]

i have had a few trubles wit my JA
looked on the search, taken to mechanics ect....
the problem is only after 4,000 rpm the car feels like it wont go
sometimes the problem gets worse and a really small sputter at 4500 and then wont rev past 5000....
but every here or there (very rare though) it flys for like a split sec.... pulls real hard
i put new coil its a bosch super coil
new ngk iriduims, took out plugs they seam to be burning fine
new leads
its not fuel cut turbos at about 10-12 psi
i am not running the silent shafts so motor dose vibeate at hi rpm
pulled plug on knock sensor no change....
any ideas????
i had a look at the tech artical on the bosch igintor and i wonder if it will fix any thing.....
thanks

[Marc]

check your exhaust manifold

mine has got a very slight crack in it... sometimes looses power under load...splutters not all the time though.

Depends on how hot it runs crack opens wider... it seems

Is it popping at all from exhaust?

[bigd]

If the exhaust mani is cracked it should come right as it warms up because the metal expands closing the gap (obviously depends how big gap is).
Sounds like something to do with timing not advancing as your rev's go up. Check the vacuum advance located underneath the dizzy, and check that your base timing is right and check that the dizzy isn't loose. That little advance unit is a bitch of a thing and often develops leaks.

[airbats801]

sounds like it could be advance.

[Chryzla]

IS it making any unusually loud noise on boost? weird smell after a hard drive?

If so the intake pipe may have a rip in it... causes the car to run lean as the AFM isnt sensing all the air the turbo is sucking in... not a good thing

[TOMSUN]

I think it could be fuel related
Replace your fuel filter...

[OLD FART]

I think it could be fuel related
Replace your fuel filter...

I'M WITH YOU PETE HAD THE SAME PROBLEM YEARS AGO & IT TURNED OUT TO BE A PARTIALLY BLOCKED FUEL FILTER

[TOMSUN]

S73R...

How did you go???

[S73R]

sorry i been off the net 4 a while.....
cheaked fuel filter ect
still have problems..... and have a new one
the car floods
when ever i stop it floods with petol.... i think my injectors r to blame
i know i floods coz i dis conect injectors and start the car it runs 4 5 seconds then i plug em in again and away i go
dose anyone know where i can get new injectors or if some one knows if there is a common sensor that gos bad telling my injectors to dump fuel in to my motor?
i tryed gtting new injectors but i got priced $1000 :(
oh and topend dosent pull its very slugish...