Fuel cut due to broken BCS?

[MrWeedster]

Hi there.

Recently we were checking compression on my legacy turbo bjf (1993).

After that the car didnt run like it is supposed to. When i got boost at around 3000 rpm it began to stutter and at full boost around 4000 i got fuel cuts.

Brought the car to my dealer, he said the wastegate control duty solenoid valve (Boost control valve/ BCS? What is right?) is gone. He couldnt tell me if he could organise one.
So he routed the wastegate tube to the one on the pressure side of the turbo.
The car runs, but has low power. Way to less power.

So i bought a BCS on ebay. Part numbers differ. Mine is 16102AA012 and i bought a 16102AA013 from a STI.

After putting it in the car wont stutter at 3000, but fuel cuts at 5000. And that not always as it turned out.
Accel from the first to third at full throttle is no problem.
Accel in fourth at around 3000 rpm to 5000 rpm fuel cuts at 5000.

Strange problem.

Is the wrong part number the problem or is something else broken?


Next big problem to analyse this is that the check engine light doesnt work.
My dealer couldnt find problems when he was reading out the ECU, so no chance to get information from there.

[Legacy777]

Does the BCS for the STI have two ports or three? This picture has the stock BCS in it at the top left corner.

http://www.main.experiencetherave.com/s ... P_6013.JPG

If the BCS you have, has three ports and they're hooked up properly, then the ECU appears to not be controlling boost properly.

So when you turn the key to the ON position, is the Check Engine light illuminated? If not, then chances are the bulb is burned out or there may be a wiring issue. Did the dealer try to hook up their diagnostic reader, a select monitor to read the ECU?

[MrWeedster]

Yes it has three ports and i think i got them at the right places.

I think bottom to turbo pressure side, right to intake side and top to wastegate.

When i turn the key, there is no check engine light. Ill check the bulbs.

Yes the dealer did hook it up, but he said theres everything ok. I wasnt there when he checked this.

[Legacy777]

For the Legacy BCS, the lines should be connected in the following manner:

Top port: Compressor side of the turbocharger
Side port: Wastegate solenoid actuator
Bottom port: Intake resonator (must be connected pre-compressor inlet)


The stock STi boost control solenoid is only a two port solenoid. Is this an aftermarket BCS? What brand is it?

Try blowing in the ports and see which ones you can blow through without any power applied to the solenoid. Then apply 12v to the solenoid and see which ports you can blow through.

[MrWeedster]

Are you sure about the connections?

I looked, and my first info on that was crap. Its connected in that manner:

Top: Compressor side.
Side: Intake resonator
Bottom: Wastegate

Ill give it a try and connect it the way you mentioned.

What do you mean with two port? Two ports for tubes or two ports in the electrical connector?

The two parts look exactly the same, theres nothing missing on the sti one. Brand is Denso, original subaru, no aftermarket.

[MrWeedster]

Short update: It works the way you mentioned.

I flipped side and bottom, now it works.

Thanks for your help.

[Legacy777]

You're welcome. Glad it works.

Some of the models got a different type of boost control setup called a bleed setup vs. a blocking setup, which is used with the three port solenoid.