Anybody build a circuit to drive the stock boost solenoid?

[All_talk]

Has anybody designed an electronic circuit to drive the stock boost control solenoid? All you should need is a PWM output at something close to the stock frequency. You might even be able to use an IC as simple as a 555 timer with a FET for the output. I really like the idea of just tweaking a pot to adjust boost.

You would probably have to rig up a load (resistive/inductive) to put into the stock circuit so the ECU wouldn’t throw a code.

Just a thought.
Gary

[vrg3]

Yeah, I did that once. I did use a 555, a comparator, and a power transistor (it was a Darlington BJT rather than a FET, but same difference). It was basically the electronic equivalent of a bleed-type manual boost controller; instead of turning the knob on the MBC, you'd turn the knob on the potentiometer.

You can pacify the ECU with a 470-ohm 1/2-watt resistor.

Give it a shot!

[Arctic Assassian]

^ghetto tech at its most basic... But awesome!
I like the homemade FCD the best.

[Legacy777]

Quick question, what would you have to tap into to let the circuit know what your manifold pressure is? Where's your input/sensing signal coming from?

[vrg3]

The circuit I'm describing has no sensing signal. It just runs the solenoid at a fixed duty cycle (chosen by the position of a knob) to bleed off a certain amount of pressure from the wastegate actuator's diaphragm.

[Legacy777]

With that setup, spool time should actually increase since the wastegate actuator will be seeing more boost before the desired opening time, when compared to the stock setup, or a MBC.

[vrg3]

It is the equivalent of a bleed-type manual boost controller, like the standard TurboXS MBC.

So, yes, spoolup will not be as snappy as with an EBC (like the stock boost control) or a ball-and-spring MBC. On the other hand, it is easier to dial in and is much less likely to cause boost spiking.

[All_talk]

You could add a pressure switch set just below wastegate boost to turn the circuit on. that would give you normal spool up and the solenoid wouldn't have to run all the time.

Gary

[vrg3]

You'd probably get some boost spiking with that approach, but you might like the results better, yes.