RX7 Boost problem, please help!!!

[metalman]

I'm having a nightmare with my 92 3rd gen rex and hope someone out there has had the same problem and can help me out before i set light to the blasted thing!

It's running standard twins, HKS induction, APEXI ECU and a free flowing exhaust.

I would say it's an over boosting problem, for some reason when the 2nd turbo comes in the boost keeps rising up to around 16 psi (was only 10 psi) on the gauge and 1.04 on my commander, also this time the fuel cut off. I can also hear a kind of whistling/leaking of air when this happens but can't find any split hoses anywhere. If it was a problem with the intercooler/pipes i would understand the whistling noise but it doesn't explain the rise in boost pressure?

It's obviously a problem that's hard to find without the aid of a rolling road or diagnostics but, if anyone has any ideas on what this could be, PLEASE HELP ME! It's driving me crazy!

Thankyou people, J.

[cptsideways]

Actuator pressure feed leak, ie the actuator does not see the boost pressure, would explain it all.

[metalman]

Ok good call, would this be a problem with one of the small hoses off the side of the actuator or something similar? I've had a good look at all these from under the car and can't see anything but will have another look.
Cheers for the help.

[r5gttgaz]

Could be a tired actuator, the free flowing exhaust may be increasing boost.

Edited by r5gttgaz on Saturday 7th October 14:11

[mave]

I'd recommend posting the question on mazdarotary; the boost management system on the twin turbo is quite complex, can't remember how many solenoids and boost or vacuum lines there are, but it can take some time to fault find, even for the experts!

[J.j.]

Have you had your Apexi Power FC mapped?? The ECU's base map is for standard car only.

[iaint]

Hi,

There are a sew diagrams floating around on www.mazdarotaryclub.com also worth registering on www.fduk.org (uk 3rd gen owners club).

Could be a failed actualtor or one ofn the one-way pill valves. the boost control system (aka 'rats nest') is prone to problems - it's complex and 15 years old in our cars! The diagram might help you or try one of the experts (linked off maz rotary)!

[metalman]

Thanks everyone for the help, much appreciated! The power fc has been mapped and it's all been running sweet for almost three years now so can't see there being anything on the car set up wrong, more a problem with the miles of rubber hose or the actuator etc. I've booked it into rotechniks for next week as they've sorted it out before and done a great job. (Fuel hose split, engine up in flames! It was a real mess.)

Cheers again!