Boost Control (limiting boost in 1/2 gear)

For discussing how to choose sensors and create a wiring harness for all Bowling and Grippo versions of the MegaSquirt® EFI controller.
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MustangMike
MegaSquirt Newbie
Posts: 6
Joined: Wed Dec 27, 2006 7:24 pm
Location: Miami,FL
Contact:

Boost Control (limiting boost in 1/2 gear)

Post by MustangMike »

What would be the best way to limit boost in 1st and 2nd gear using the MS2 pcb3 v2.888. See sig for car info. Basically if I could limit 1/2 to 5psi (current wastegate spring pressure) by leaving a GM solenoid closed then turning it on to bleed off the vac/boost line in 3/4 gear or mph based maybe.
Has anybody got this setup already? I tried searching and couldn't find anything besides basic boost control topics.
I guess to have this work I will need another sensor, preferably a MPH drive shaft type sensor setup that could be input for other cool MS stuff.
So basically I guess i have the MPH sensor as a on/off port input to turn the gm solenoid control on at a certain MPH to get boost control. That's basically. Does anyone have any more technical input for me to make this happen. If there was a simple mph sensor kit for Ms all sorts of cool info could be displayed like MPG horsepower etc.
All input greatly appreciated.
Mike
MS2 v3.0 PCB, 2.89 firm, w Scotts Adpt board 2.0a
TunerStudio, LC-1 WB O2.
93' LX 5.0 5spd, Original owner 21k mi. Black on Grey
Turbonetics 62-1, GT40 Heads Port/Polish, Wolverine Cam, 70mm TB
Matt Cramer
Super Squirter
Posts: 2951
Joined: Sat Jul 03, 2004 11:35 am

Re: Boost Control (limiting boost in 1/2 gear)

Post by Matt Cramer »

Considering that the 2.888 code doesn't have boost control at all, you're looking at some serious reprogramming to add this. I'm not a code guru, but you would need to use an unused analog pin either as a VSS input with a frequency to voltage converter, or make some sort of resistor box / voltage divider device on the shifter that would send a different voltage to the output depending on your gear position. Then you'd need to write a boost control algorithm.

It's possible the GPIO board may support this kind of thing too when it comes out.
MustangMike
MegaSquirt Newbie
Posts: 6
Joined: Wed Dec 27, 2006 7:24 pm
Location: Miami,FL
Contact:

Re: Boost Control (limiting boost in 1/2 gear)

Post by MustangMike »

Thanks guys.
I guess I'll just wait for GPIO and hope.
I know there isnt really "code" for boost control, but MS is pretty versatile, and I was thinking that I could use the spareport setting to open a gm vacuum solenoid at xx map to bleed off boost. I was just trying to bounce it off the forums to see if anyone had any ideas for a speed input or some way to determine the other variable for the solenoid to open.
MS2 v3.0 PCB, 2.89 firm, w Scotts Adpt board 2.0a
TunerStudio, LC-1 WB O2.
93' LX 5.0 5spd, Original owner 21k mi. Black on Grey
Turbonetics 62-1, GT40 Heads Port/Polish, Wolverine Cam, 70mm TB
Matt Cramer
Super Squirter
Posts: 2951
Joined: Sat Jul 03, 2004 11:35 am

Re: Boost Control (limiting boost in 1/2 gear)

Post by Matt Cramer »

Somebody tried using a generic on/off output for boost control a while ago - it didn't get a very steady boost level.
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