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3 Port Electronic Boost Control Solenoid: What and Why?

November 8th, 2023 | 3 min read

By Alan Jackson

That is a mouthful, so from now on, I’m going to refer to this as EBCS. But what is a 3 Port EBCS? How is it different than stock? Why is it a good upgrade? Do you really need it? Let’s knock those questions out one by one…

What is a 3 Port EBCS and how is it different than stock?

The 3 Port EBCS is a solenoid that does just what the name implies. It controls boost pressure. In a turbocharged vehicle, there are a couple components that make up the boost control system. The wastegate and the boost controller. The wastegate has a spring that is set at a certain pressure and boost is controlled by over pressurizing the spring allowing the actuator to open and bypass hot exhaust gases around the turbine. In order to run more boost than what the spring is rated at, the boost controller will divert pressure and keep the wastegate closed until the desired boost level is reached.



OEM WRX Boost Control Solenoid


OEM Speed3 Boost Control Solenoid


Most of the applications we see for 3 port EBCS upgrades are Mazdaspeed 3 and 6, Subaru WRX and STI models from 2002-2021, and Mitsubishi Evolution 2008-2015. There are plenty more applications that can use them, but the niches that we've historically been involved in are for these platforms.

A 3 Port EBCS does this by interrupting the boost signal between a boost source and the wastegate.  It then redirects this pressure back to the intake. Typical OEM boost controllers are of the 2 Port variety and operate by bleeding off this pressure signal between the boost source and wastegate. The bleed method is simple, but it also reacts slower than the interrupt method and with less precision.

Why is it a good upgrade?

The 3 Port EBCS is a good upgrade because with better boost control, you get a more precisely dialed in tune.


GrimmSpeed's FA20DIT EBCS vs Stock. This shows how much more controlled the EBCS is 
compared to the stock Bleeder BCS.


But wait! There is more!

The turbo has a lot to do with what kind of boost controller is necessary on a factory car. Most OEM turbos are not too big and don’t run very high boost pressure, and therefore they are not very difficult to control at low boost levels. However, when you want to raise the boost pressure, you start running into boost spikes and dips and you get a rough boost curve which translates into rough power output. In this case, upgrading to a 3 port EBCS will provide smoother power delivery and better/more precise control over boost.

This pressure spike and pressure dip becomes even more evident when you upgrade to a larger than stock turbo. The stock 2 Port solenoid can’t react fast enough once the larger turbos, which have more inertia, hit their target boost. You will see the car sail right past the boost target then taper off and fall below the boost target as the car tries to wrangle in the pressure. This oscillation gets worse and worse the bigger you go.

But maybe you don’t want to upgrade to a massive turbo. Maybe you will be happy with a quick spooling, smaller upgrade. Even still, a 3 Port EBCS will make tuning these smaller turbos much easier as well. With the smaller turbos that are capable of much higher boost pressures than stock, especially when they are operated on stock engines, you will be more concerned with limiting the quick spool up in order to save your engine from making too much torque too early. Where the factory EBCS will struggle with controlling the rapid increase in boost pressure, a 3 Port EBCS will have no problems safely ramping up boost pressure to ensure the tuner controls the onset of peak torque.


As shown above, many vehicle specific EBCS kits will come with extra tubing, mounting hardware, and many even come pre wired to plug right into a factory engine harness like the Cobb Tuning version shown here.  If you are changing a non-turbo car over to a turbo and plan to use a 3 port EBCS, you'll need to wire in the solenoid yourself into whatever tuning device your are using.

Do you really need it?

I guess the best way to answer this question is by asking another one. How much do you care about reliability, driveability, overall performance, etc.? If all you want to do is rip it here and there and get by with the minimum it takes to have some fun, well then no, you don't need it. But if you demand the best experience you can get from your car and you want to know that the performance isn't being compromised in any way, a 3 port boost controller is a wise choice. There are some situations where it is required if your setup demands it, though. If you're pushing the car hard, keep this in the back of your mind.

Do I need a custom tune to run a 3 port boost controller?

When installing a 3 port EBCS, you will need a custom tune. Because the 3 Port EBCS operates so much more efficiently, without tuning, your car could over boost if using factory boost targets.

Where can I find an EBCS for my car?

Here are some helpful links to find the right one. If your car isn't here, a universal one might do the trick! You'll just have to wire it into your existing harness.

Mazdaspeed 3 - Grimmspeed or Cobb Tuning
Mazdaspeed 6 - Grimmspeed or Cobb Tuning (same fitment as MS3)
Subaru WRX | STI 2002-2007 - Cobb Tuning
Subaru WRX | STI 2008-2014 | Legacy GT 2005-2009 - Grimmspeed or Cobb Tuning
Subaru WRX 2015-2021 - Grimmspeed
Mitsubishi Evolution 2008-2015 - Grimmspeed


This post was originally published in March, 2016 but has been updated to reflect current parts and accurate information!