Right as some know i have a problem of loosing alot of power at high revs. If i were to floor it in 2nd it would go well until about 4500 where it would start to ease off until at about 5800 where it would go no higher.

 

I have tried the following and am starting to run out of ideas.

Replaced fuel pump, filter and pressure regulator.

Wired a 12v to pump to check pump controller.

Changed coil packs.

Changed timing belt to make sure it hadnt slipped a tooth(it hadn't)

Ign timing 13-15 degrees.

Did change sparks but admittedly they're now dodgy import plugs.

Installed de-cat to check 4clogged cats.

Can't really find any boost leak.

Resistances of injectors were ok.

Boost pressure seems fine and reaches about 10psi on aftermarket gauge.

Mas and cas voltages were ok (maybe should try replacements tho?)

Compression results within spec, all around 155-160.

 

Think thats about it.

Ideas? I've ran out of them.

Just a weak engine?

She pulls fine at lower revs.

 

Cheers for any ideas. :)

Heya, i just wondered if there is a fuel pick-up strainer in the tank on a z? It does sound like fuel starvation, maybe the gauze is a bit clogged? Ive known it on other cars :)

Maybe worth getting an SE or JWT chip to sort out your fuel mapping see if this help. If it doesn't all is not lost is still an upgrade you would have done eventually I imagine.

Funny you say that Stu, cos i did exactly that about a month ago, great excuse! As suspected made no difference though. I have a boost controller waiting to be installed to go with it but i dont want to do anything till this problems sorted obviously.

 

Interesting suggestion Trevz, when replacing the fuel pump that is changed aswell though as they're pretty much joined together!

I think i'm gunna get a fuel pressure gauge, i already got one but its mechanical and i dont know how the hell you're supposed to read it when doing 5000rpm under boost..

Any ideas where to get 1 from?