PRODUCT DETAILS
Haltech 4 Port Boost Control Solenoid
This is the valve that lets your ECU decide how much boost you make. Instead of a wastegate spring setting a fixed pressure and that being the end of it, a boost control solenoid bleeds pressure between your source and your wastegate actuator, and your ECU tells it exactly how much to bleed. That means boost by gear, by rpm, by throttle position, or by anything else you want to base it on. This four-port unit runs at 33Hz and integrates directly with Haltech ECUs.
What A Boost Control Solenoid Actually Does
Worth understanding if you haven't run one, because it explains the four ports. Your wastegate opens when pressure acting on its actuator overcomes the spring. Left alone, that happens at spring pressure and you get whatever boost that produces.
A boost control solenoid sits between your pressure source and the actuator, and it rapidly opens and closes to control how much pressure the actuator actually sees. Bleed some off and the wastegate stays shut longer, so boost climbs higher. Your ECU controls the duty cycle, which is how you get a target boost number rather than a spring number, and how you get consistency as conditions change.
The 33Hz operating frequency matters here. Faster switching means finer control and more stable boost, especially during transitions when the turbo is spooling and pressure is changing quickly.
Three Port Or Four Port?
The common question, so here's the plain answer.
A three-port solenoid controls only the bottom port of your wastegate actuator. It works, and it's what a lot of setups use.
A four-port controls both sides of the actuator, top and bottom. That gives you a wider control range, because you can actively hold the wastegate closed for faster spool and then vent the top side to open it precisely. On a setup where you want boost by gear, aggressive spool, or high boost targets, the extra range is what lets you get there.
The tradeoff is that four ports are more to plumb correctly, which is why plumbing is where most people run into trouble.
Getting The Plumbing Right
This is where four-port solenoids earn their reputation for being confusing, so slow down here. Each of the four ports has a specific job, and connecting them wrong will give you anything from no boost control at all to a wastegate that won't open when it needs to.
In general terms, one port takes pressure from your source, one feeds the bottom of the wastegate actuator, one feeds the top of the actuator, and one vents. Which physical port is which varies by solenoid, so follow Haltech's documentation for this specific unit rather than a diagram you found for a different brand's valve. That's the single most common way people get this wrong, and MAC-style four-port diagrams don't necessarily map to this solenoid.
Take the time to plumb it correctly the first time, verify your control direction on a low boost target before you turn anything up, and you'll save yourself a lot of confusion at the dyno.
Built To Live In An Engine Bay
Boost control solenoids sit in a hot, vibrating environment and cycle constantly, so construction matters. This one is built to handle heat, vibration, and the general abuse of a motorsport engine bay, and it's compact enough to mount just about anywhere you've got room. The included isolated mount is worth using, since isolating it from vibration extends its life and cuts down on the buzzing noise a hard-mounted solenoid transmits into the chassis.
Everything You Need Is Included
No sourcing fittings separately or hunting for a bracket halfway through the install:
- 1x Haltech 4 port boost control solenoid
- 4x 1/8" NPT to 5/16" barb fittings
- 1x brass vent
- 1x DTM2 connector set
- 1x M6 isolated mount
- 1x mounting bracket with hardware
Who Should Run This Solenoid
This is for anyone running a Haltech ECU on a turbo setup who wants real control over boost rather than living with what the wastegate spring gives them. Single turbo, twin turbo, street car, or full competition build, it's the piece that turns boost into something you tune rather than something you accept. Plumb it properly, set it up on a conservative target first, and go dial in the boost curve you actually want.
Type: 4 port electronic boost control solenoid. Frequency: 33Hz. Integration: designed for Haltech ECUs. Includes: solenoid, four 1/8" NPT to 5/16" barb fittings, brass vent, DTM2 connector set, M6 isolated mount, and mounting bracket with hardware.