5 litre reving issues

[krawlr]

hey all ive recently been helping a mate on his vq statesmen 5 litre hsv it has a fresh/new motor only done 20 thou k's now heres the problem...... when the car is in park and you put your foot down to rev it up it only hits 4 and a half grand and wont go any further when you are driving the car and mash the floor from a stand still it seems to be slightly slugish off the line but once it hits 2 grand it pulls hard all the way to 4 and a half grand and just wont go any further the auto will hold 4 and a half g and when you back off slightly it will chang gear fine and pull hard to 4 and a half grand and just not go any further and does this through every gear.. we have changed every single electronic part on the motor and it still does it.. not one error code has been throughn at all have had car to about 4 mechanics and they cant pin point it... have been told could be a rooted valve spring but i dont personally think this could be the case .. could it be auto related?? have had fuel pressure checked is fine have had spark checked is fine has new dizzy new coil new ignition module new filters in fuel lines new injectors.. the list goes on but still no fix of problem has anyone else had a similar issue would be a great help

[Brett_jjj]

It could be a blocked catalytic converter or muffler.This will kill the engine power and revs and will make it seem like its running crook.Its worth checking,especially seeing you have changed or tested a lot of parts with no results.

[klrkid]

2nd the cat. try some grammar and punctuation dude so we can all read easy

[Warranty Void]

Maybe you'll get more help if you stick this in the V8 section.
Collapsed air filter/induction blockage?
Collapsed exhast baffle/catalytic convertor blocked? Pull the exhaust from before the cat and see what happens?
Coil earth? Did the block get painted? Whack a multimeter from -ve battery post to engine block and check the block is earthed ok.
You need to get that feller on to a dyno mate before you lose a piston to a lean out or something. Also need mixtures checked thru rev range and load so dyno is best way to go.
Also mate, did it do this from day one with the fresh motor or did it go ok for a while and now it's not?
Where are you located?

[krawlr]

thanks for the help...
the car has brand new exhaust on it and extractors so isnt the exhaust...
have had air fuel ratio's checked were fine...
will be checking earths tonite on motor...
is it possible that the tourque converter is rooted or has an issue??

[reaper01]

so the old engine is a hsv engine and has the knock sensor? does the new motor have the knock sensor?