Xcite24

Iv recently had my FD3 on a rolling road, to find that its way down on power. (211bhp)
Now also on the print out the graph is showing that the second turbo is only producing 0.5 bar (approx 6psi) But the place couldnt tell me if this was been produced by the 1st turbo still spooling or the 2nd turbo loosing pressure.
As far as im aware the car is pretty standard apart from a full HKS exhaust system, and a mushroom intake feeding both turbos. Now they have told me they have checked all the upper vacuum pipes, but cant get down to the 1's around the turbo without removing all the unit in which they would need for a couple of days.
So i was wondering if any 1 could direct me on were to possibly look next.

dgeesaman

iTrader: (7)

On the graph, what is the max boost below 4500rpm, and above 4500rpm?

Dave

Xcite24

hey dave, below 4500 rpm the max achieved was 11.6 psi @ 3500rpm and after 4500rpm its 7psi @ 6500RPM. lowest been 6 psi @ 4700 and only rising 1 psi over 2000rpm

dgeesaman

iTrader: (7)

Above 4500 both turbos are operational. In almost all cases, lowered boost is not caused by one of them underperforming, but either a lack of flow feeding the exhaust side or a leak allowing some of the charge out.

The exhaust flow going in is controlled by the turbo control valve (and actuator and solenoids) and the precontrol valve (and actuator and solenoid). The charged intake is contained by the charge relief valve and air bypass valve. I suggest going to http://www.autosportracetech.com/RX-7/rx7stuff.htm and investigating these parts. The problem usually ends up being traced back all the way to a loose vacuum hose, bad check valve, or sticking solenoid. So if the shop is focusing on the turbo units themselves, IMO they don't know what they're doing.

Also, www.fd3s.net/boost_test.html shows a diagnostic sequence which verifies the major components.

Dave

Xcite24

Right i guess the next step is to check then that the charge relief valve is working properly. Is there any particular vacuum pipes i should be focusing on? i dont know if its anything to do with it.. but from about 3200 Upwards a whistleing noise appears (like a boost leak) And i think i read somewere that the second turbo begins spooling around 3000RPM ready for the change over ? Is this suggesting that its more than likely a vacuum pipe related to the 2nd turbo with the noise and lack of boost.

Thanks for the help on this matter so far