Yes, the admin even needs help sometimes. I really dont know whats going on with my buddys rx7. Its a 2nd gen with a Race Ported 13BT using the stock turbo setup. The turbo is good, some minor shaft play, no oil leaking. The wastegate is suppose to be stock set at 6~7psi. Using a Greddy Front mount, and all nice 2.5in piping. There are no leaks anywhere. Ok so heres the problem, at 6000rpms the boost falls down to 4psi. I figured, thats not to big of a deal. So we get his boost controller on, and set it at 10psi. It holds fine until 6000 it drops right back down to 4psi and the power feels like ----. I take the boost controller off, and I completely dissconnect the wastegate. I figure it should spike now, but hey guess what happens..? yup spikes up to maybe 7psi then comes right back down to 4psi with the wastegate unplugged. So were thinking the flapper is being pushed open by exhaust gases at the high rpms. So we put a helper spring on the wastegate arm. Still 4psi. Took the turbo off and inspected, just some very small hairline cracks in the exhaust manifold, Nothing major at all. Were running out of options. He had the stock exhaust setup on, so maybe we thought it was to restrictive.. again we took it off and 4psi.

Anyone else have any ideas or theroys?

 

Cam timing off? Slipped a tooth?

Head problems? Did this just start happening or is this a new turbo?

A guy on Honda-Tech had this problem back a month or so ago...tried & replaced everything except the head for a while and nothing worked.

I think it ended up being something to do with his cams or valves.

 

there is no cams or valves on a rotary motor

is it an s4 or an s5 jeff? i would look into the cat... sounds like a plugged exhaust to me

 

lol its a rotary! it doesnt have a head, valves, cam timing etc. And like I said, we already took the exhaust completely off. The car doesnt have a cat anyways.

And its a S5

 

hmm... i dont know what to say, i guess start lookeing for vacuum leaks. Half the ppl i know say that the stock s5's wont hold boost @ high rpm and the other half say they creep.and by whole exhaust you mean from the down pipe back or you took off the down pipe too? there is 2 precats in the down pipe that fail all the time


Edit:
what kinda vacuum numbers you pulling @ idle?

 

maybe the turbo is too small to breath at those higher rpm's...
I know when my srt was stock..
I could set the boost to 19psi but at 4400 it would drop down to 12...

 

DOH...shows how much I know about anythng that isnt a honda!

 

Yes, the turbo is probably a little on the small side for what the motor is, but it shouldnt fall off that much boost. Especially if the wastegate is wired shut, it still should produce more boost than that.

He has a 3in downpipe off the turbo, and we dissconnected the exhaust right off that. It can breathe just fine. He's pulling about 17in of vac at idle. I really dont think its a vac leak, because in order to loose 8 psi, its going to be very noticable.

 

17in @ idle is very good for a ported motor, hmm im kinda stumped.... what fuel managment and are you using a fcd?

 

Stock ECU w/ FCD