no one has a clue

[maximtaylor]

The Power fc controls boost by using the duty cycle of the solenoid valve. This is a percentage of open and closed cycles for the solenoid valve, which in turn controls the wastegate

This is otherwise known as base duty, wastegate duty or solenoid valve duty. It is this percentage which gives different levels of boost, the lower the percentage, the lower the boost.

screen looks a little like this:

Settings 1
Boost primary                 0.8 bar   56%
Boost Secondary            0.7 bar   62%

Settings 2
Boost primary                 0.9 bar   62%
Boost Secondary            0.8 bar   70%




(these numbers are accessable on a Apexi commander.

When you nail the throttle, the solenoid valve which controls the wastegate jumps straight to 56%  duty cycle which will give you xxx amount of boost, then the ecu tries to compensate for any over or under boost to reach the desired pressure (0.8 bar). Think of it as the 56% is the intial boost level, the 0.8 bar is the target boost figure.

If the % figure is too high, then the boost will initially go way beyond the 0.8 bar (spike), then recover to 0.8 bar.

Too low a percentage and the boost will be laggy and take a while to reach 0.8 bar.

A stock car will boost properly with the pre programmed figures above. If you start changing downpipe etc and reducing restriction, then the extra gas flow will mean that boost will jump up, so you\'ll need the reduce each of the percentage values, normally about 6-10% off each of the values, or you\'ll spike.

Any clearer?

Regards

Max

[Davegtt]

Right, so this explains why you get boost spikes when you change components in the car, as the base map of the std ECU is configured for a static setup, i.e as it rolls out of the factory!

Thanks for the info mate

[Martiny]

I seem to THINK only the early cars had plastic Y Pipes, and Mazda changed them later?

[20B_boy]

Yep, placky y-pipes went in the \'95/\'96 along with the 8bit ecu\'s I think?

[doggyfizzle]

i have had an idea,although how bright it is remains to be seen.last year i had a mitsubishi gto twin turbo,i decided to try a mod i read about,on how to increase boost.it involved using a valve bought from an aquarium store and some pipe,to make a cheap boost controller.
now,shall i try this on my rx7,putting the valve in the pipe that goes to my wastegate controller and fully opening the valve,then slowly closing it until im back to stock boost,or am i totally wrong?
if i buy a proper boost controller,would this cure my overboost problem?im sorry i dont know much about turbo engines and especially a rotary,so dont scream at me  too much:)