JesseT

One decent cost OEM alternative used in VAGs for the boost control valve:
http://shop.vems.hu/catalog/pneumati...3way-p-85.html

Has worked for me nicely for a few years. Best in the mapping with MS is that the boost can be mapped as a function of the throttle position. Very nice for road use. Half throttle --> low boost, full throttle --> full boost.

SteveT

Dragging up an old topic here...

So my home brew Zetec Turbo is running Megasquirt 3 and boost is currently just set by actuator pre-load, with a hose between the turbo and actuator. I'd like to use the Megasquirt boost control function, which I believe pulses a boost control solenoid rapidly in order to maintain the desired boost level, i.e. bleeding air or routing air to the wastegate actuator as necessary.

So my question is, can I just use the standard ERST amal valve as a boost control solenoid, and control this using Megasquirt?

Is the amal valve capable of working fast enough, or is it better to get a specific 'boost control solenoid'? I believe that the amal/solenoid cannot measure the boost level, it just does opens/closes as the ecu instructs it, so is the standard Amal ok?


I am right in my understanding of how the system works....
- the ecu initially tells the solenoid to bleed air, so that the turbo can reach desired boost quickly (i.e. actuator does not open at all).
- when boost target is reached the solenoid pulses at a specified duty cycle, with air bled or directed to actuator as required, to hold required boost.


MS3 boost control screens....



Open-loop boost control tuning: (I believe this table just sets the duty cycle for the solenoid valve).


Optional Closed-loop boost control. (So are these the actual MAP values you're trying to target in kPa? I.e. a value of 200 = 1 atmosphere + 1 bar boost =15 psi boost?)



What adjustments do I make to actuator after fitting the solenoid? I've read I should release some of the pre-load on it, but what are the reasons for this? I understand that it won't need the pre-load anymore, since the solenoid acts as a bleed? Is that right?

Any advice and help on this area is welcome!

Steve

Rob_DOHC

iTrader: (4)

Hi there,

Your mostly correct on all counts I believe the AMAL valve could be used, however I wouldn't. Solenoids are so cheap that it wouldn't make much sense using a 20yr old (known to fail) item.

What kind of boost are you running at the moment? If it is just at the actuators standard rating then no you don't have to reduce pre-load. I would personally adjust it to 10psi and use the ecu to control above this. Start off by tuning in open loop mode and when it is working well switch over and begin tuning the closed loop, the closed loop does take some fiddling before it works really well but the benefits are worth it.

Rob,

Rob_DOHC

iTrader: (4)

Also your vac line plumbing will/should depend upon valve type. If the valve were to fail you will want the boost to fall back to actuator defined levels.

Some valves are normally open others are normally closed with out energising their coils. Normally closed would mean it would probably fail closed, vice versa with normally open, failing open and bleeding the top section of the actuator would be bad news.

Good luck and happy tinkering

Karlos G

iTrader: (4)

Exactly as Rob says above.
But I would always set the actuator pre-load to half your desired boost, so 10psi for 20psi 15psi for 30psi etc.

Rogeyboy

iTrader: (2)

I run a gizzmo boost control solenoid, works nicely with the OFAM ecu im running.
TPS selective boost works well too, if i start to wheelspin mid corner i lift a fraction and it drops boost by 0.1bar every 10% of throttle i lift off. Then plant it again once you start to straighten up and woooshh off you go again mr sulu...

SteveT

Thanks for your replies guys.

I'm only running 11 psi I'm using a -31 actuator with a 4x4 cossie turbo. It's a decompression plate self-mapped engine so I'm playing it safe, and in a Westfield kit car it's still pretty rapid.

I'm keen to get the turbo to spool quicker and hold the correct boost, but I guess really I just want to tinker with it and try this feature of megasquirt.
I'll get a proper solenoid then, and not use the amal valve.


I've got FIdle free to use with MS Boost Control. I think this goes to ground when activated. Does that mean I can just connect the boost solenoid to +12V and FIdle and it'll ground through FIdle when the ecu triggers it?

Steve