Components needed:

(1) MOSFET IRLZ44 (IRLZ44NPBF-ND)
(1) 100ohm resistor
(1) 10k resistor
(1) diode 1N4002 (1N4002DICT-ND)
(1) Fast activing 3-Port valve (boost solenoid) gmpartsdirect.com part #1997152

MegaSquirt MB side:



Gate (pin1) goes to JS2. Installed with the 100ohm resistor inline.

Drain (pin2) goes to IAC2A which goes to pin 29 on the DB37 connector. From there you'll wire out of the DB37 connector to a wire on the solenoid.

Source (pin3) goes to the ground. I used the ground of the proto area.

Install the 10k resistor between Pin 1 and Ground.

Mount the FET to the case somewhere and use some heatsink compound to keep it cool. I used a heatsink and used the proto area.

Pictures:










Solenoid side:

I haven't gotten this far. But what you'll do is wire the diode between the DB37 source wire and +12v wires of the solenoid. This is suggested to filter out voltage spikes.



The Cathode (or silverbar) goes to the positive wire.


MS software side:





Set Closed Loop kPa to 0, this uses the duty cycle targets to control boost, the kPa targets have been known to not work as well. The higher the % in the row, the higher the boost.

 

Nice writeup, i'm sort of jealous of your camera, just sort of.

 

I'd add that you can get the solenoid from gmpartsdirect.com part #1997152, and you can get a connector for it from most 90's GM products, look on the windshield washer reservoir. The junkyard I went to let me have it for free.

 

I already have the FM solenoid so i didn't add that, but yes...as seen here:

http://forums.turbobricks.com/showthread.php?t=80599

 

This is the solenoid duty cycle table you asked me about.
Remember, this is set for my falling boost. If you use my settings, you'll break your ****. I've also included the boost control parameters menu.

Cautiously implemented, this table *should* be applicable to other greddy cars wanting to run 14 psi.

Using a GM Typhoon 3 port solenoid, but any should work.

 

yeah 98% at 7000rpms would put my turbo past 20psi :gay:

 

Here is my boost curve with rpm. Upper red line shows 15 psi. Lower shows 13 psi. I don't know how to make MLV show a grid yet.

 

Scott, it looks like your gate->source resistor is brown-black-red which would be 1k instead of brown-black-orange, whick would be 10k. It might just be the lighting or whatever, but I though I'd bring it up.

 

damn you're right...i used the wrong reisitor....good catch....it's fixed...I had to flip the FET around and bend the pins 90* so the heatsink could fit under the case anyways....it was about 1mm too tall, so no worries.


another note....for the duty cycle target....since I'm not using a TPS, I'd basically only need a 0% and 100% rows correct?

 

yeah, just make sure all the values in all 8 vertical rows are the same.

 

Am I correct in thinking that when boost control in enabled, "output 1/boost" should be green, much like "Fuel Pump on" and "FIdle/spark" are on the MT main page? Or, will "output 1/boost" turn green when conditions for boost control are met, like pressure going above ambient?

I've triple checked everything and cannot get the soleniod to cycle.

 

Heh, i just had all the parts for this and other MS mods show up at my door friday. Guess I need to get my butt in gear and finish my MS stuff.

 

cool, thanks for writing this up. Where are you getting your electrical components from?

 

Does anyone know of a supplier similar to GMParts in the UK? GMParts wont ship outside of America :(
Also where does the solenoid get plumbed in? If someone could show me on a diagram similar to this (http://home.comcast.net/~phantoms/va...rbo_system.jpg) I'd appreciate it.

 

You replace the MBC...so between the boost source and wastegate.


FWIW, I'm not using the GM solenoid...I'm using a Flyin' Miata one...

It's ARO brand, very similar to this: http://airinc.thomasnet.com/viewitem...ies?&forward=1

and this to be specific: http://flyinmiata.com/index.php?dept...7;20%201990-97

 

here, i was working on wiring it up today....

 

That seems very expensive compared to the GMParts one.

If #8 is the actuator it goes in here....?

(click to enlarge)

 

yep sure does.

 

the actual ARO valve FM uses can be found for under $25

 

ok I lied, best price I could find was $27 here: http://www.grainger.com

part#6jj52 however they have the exhaust port "muffler" spongy thing, which I'm thinking about ordering if the vavle is loud at all.

FWIW, I used a new GM solenoid and it failed on me after about 2 months of use...dunno why.