legacycentral bbs

I was thinking about this this morning. Building a cheap / simple EBC should not be so complicated !

but since i'm no electronician, i'll ask you guys what you think

Simple functionning principe (very simple)

the pressure sensor generates a voltage in relation with PSI (as we saw for building an FCD).
A certain circuit "monitor" that voltage, and once this voltage goes higher that a certain limit, it trigs a solenoid valve, wich stay opened until the voltage comes bellow the limit. (this operation would be executed several times a second, so this would produce a relatively clean boost.) . This Voltage limit should be adjustable with something like a inverted Potentionmeter.. i don't know anything in that


Is this sound stupid ? or would it become a Cheap EBC that we, poor legacy owner, could build to get a more precise _ and not variating with weather_ boost controler ?

thanx

ok i just talked to someone here who has some electronic knowledge, and he sais that would be possible using a simple transistor and a variable resistor.

but, is the working principe is ok ?

i think i'll seriously consider giving it a try !

I was planning on trying one of these out when I get ready to turn up the boost.

The principle's okay, but you really need to damp the signal out so you don't end up with the poor wastegate control solenoid oscillating to its death. Solenoid valves really should be pulse width modulated to get smooth results.

My plan was a circuit like the following:



I haven't worked out what the exact parts and values would be, but it'd be a couple of bucks of parts (it would use the stock pressure sensor and wastegate bleed solenoid).

My concerns are 1) this controller will be very susceptible to boost spiking, 2) I don't know how the ECU manages its "pressure exchange" system, but it's possible that this controller could "miss" the boost value often enough due to the ECU sensing barometric pressure that it would behave unpredictably.

I'd avoid a simple resistor-transistor circuit because you don't want to load the MAP sensor (I don't know its output impedance but it's probably not high).

[edited to correct broken image link]

What you speak of is BoostMonkey . that was the idea behind it. Kris doesn't even make that much profit on each unit. it'll prolly cost about 100 bux to build a proper one with TPS sensing and whatnot. I think it needs a microcontroller board.

-IggDawg

The BoostMonkey, from what I understand, is pretty different.

It actually does PWM to regulate boost, but I think it does this just using a 555 timer rather than a microcontroller. The big deal with the BoostMonkey is that it also checks the TPS reading against a threshold to decide which of two boost settings to use.

In the end I think a simple ball-and-spring boost controller would probably be the simplest way to control boost.

Is there anyone who has a PCB layout for the unit above.

I live in Sweden and it's a little hard to get this unit over here...

//Mattias