Fatman

Apologies if this is a real newbie question, but what is a boost solenoid? Further - why are some cars originally supplied with 3-port ones versus 2-port ones? Is this linked to the fact that modded cars sometimes have 3-port units?

Cheers...
Ben

LB4

I believe pre 98 cars had the 3 port valve fitted, later had the 2 port.
This is the valve that is operated by the ECU so that when a pre-determined boost level is reached the wastegate is operated.
With a 2 port the boost pressure is always acting on the wastegate, but will not nessecarily (sp?) open it as it depends on the pressure reached, however once the max allowed pressure is reached the ECU closes the boost solenoid valve so that all air pressure in the take off line now acts on the wastegate diaphram instead of bleeding some off to atmosphere.
With a 3 port all air in the take off line is bleed to atmosphere and none acts on the wastegate, until the max pressure is reached when the boost valve closes and then the wastegate is opened.

I hope this makes sense... and even more i hope i am correct.
Just my understanding of it so that's not garenteed

Gary

Fatman

So essentially a 3-port solenoid provides more precise wastegate control?

LB4

Yep thats it exactly

vulnax999

iTrader: (7)

So what boost solenoid would be on a Jap WRX wagon MY94?

2 port or 3 port?

My solenoid has a pipe on top end, one at botton on side, and one underneath on end.

Thanks

Delboy2

MY94WRX will be a 3-port