Using spare outs to PWM boost control

[460stang]

I am pondering how to control my boost with one of the spare outs. I can just run a bleed and turn it on and off for low and high boost. I would like to have PWM boost control with a setting in the Spare outs that would be loaded up with fuel maps and spark maps for 87 and 94 octane fuel.

Right now I am tuned up to run 24 psi boost with 94 octane and meth injection (triggered VIA spare port). It runs good. I would like to load a different MSQ what would leave me with 10 psi no meth for cheap driving between race weekends.

Here is the thought. It may have some really big flaws, if you see them say something.

If I find a PWM solenoid that will operate at .5 amps or less I could drive it directly with one of the Ported IAC outputs. I have only hysteresis control to tune this from the MS end, but if I run a 7 psi wastegate spring and close the solenoid plumbed as a bleed at the desired boost level VIA the spare output I should have a on off on off kinda loop which is PWM and should be able to set this at any boost level from 7 psi and up.

This may osciallate or not bleed off enough boost and lack control. I will be tuned up with my 24 psi tune so I will have lots of room for error as I try to make this work at like 10 psi. I know that this will not work first time out, and the ideal situation has much more tunable software. But I figure I will be able to play with bleeds and restrictors to make this a semi workable situation.

I need to get the amp meter out and see if I could find a workable solenoid.

[Alex L]

you could go that route, i think ive seen a boost control addition in one of the code bases.

but...

Since you are using meth injection, you might want to use an interlock and 2 stage boost control. Hook up a pressure sensor on your meth feed line, relay that out to the fuel map selection input, and a normally open solinoid valve. Tee out the boost signal into 2 boost control valves, one of which is hooked in series with the solinoid. The valve 'behind' the solenoid will be your 'baseline' boost control. Once the meth injection system gets going, it will flip the map and close the valve, forcing signal into the (higher sprung) BCV. This way, if your meth injection bombs, you wont melt your pistons.

This is the method i will be doing my WI setup once I get my motor back in one piece.

[mops]

definitely let me know how you progress...
I'm wanting to do someting similar, but to a less extent.

just like electronic boost controller, i want to find a on/off type solenoid and i'll use it to block wastegate signal until boost pressure is really close to the target boost pressure (that will speedup spoolup).