DIY Active Map Clamp, How To make your own Active Map Clamp (Gen 3 3SGTE) Options

[presure2]

so while browzing around for the symtech active map clamp that both dustin and jim use, i came across this diagram on one of the srt-4 message boards,
its a DIY active map clamp.
heres a link to the original post on srt4forum.com
http://www.srtforums.com/forums/f75/how-bu...p-clamp-349656/

the part # in the diagram in the link for the diodes is for 50 of them, since you dont need 50, i modified the diagram with the pt# for 10 diodes.
heres the diagram:



here are a couple links for the parts to build one.
first the potentiometer, PT#271-342


http://www.radioshack.com/product/index.js...oductId=2062307 it costs 2.69$

the diode is 1N914 Radio Shack PT# 276-1122 whic gives you 10 diodes, and costs 1.49$

http://www.radioshack.com/product/index.js...oductId=2062576

according to the radio shack website, the store right down the street has these parts in stock, and they open @ 10am, so imma run down in a bit and grab the parts.
once i build it, ill install it and detail how to use it.


For those of you that dont understand how it works, here's a quick break down.

the map sensor on the 3rd gen 3sgte puts out a 0-5 volt signal that tells the ecu how much pressure is in the manifold.
the higher your boost level, the higher the voltage getswhen you reach max boost. when you reach right about 18psi, the ecu sees the max voltage allowed before boost cut happens, and the car bucks and tells you "STOP IT!" lol
with this device, you can "clamp" the voltage at a level just below boost cut, while allowing the sensor to work as normal below that level.
that way, you can boost above 18psi, and not hit boost cut.

:edit:
went and got the parts, assembled them, and took some pics.
ill install and test it later when Jenn gets home from work.

the pot



the diodes



here it is assembled.
power wire closest to the adjustment screw, 2 diodes wired in series, with the band at the tops (i forgot to take a pic without the heat shrink, so i just stuck a couple of the diodes in the pic for refrence) and the ground last.



once i install and test it, ill report back!

[freddy121389]

sorry just trying to help, i know nothing about this I'm reading up on them now. So locking the voltage would keep injecting the same amount of fuel no matter how much boost?

This post has been edited by freddy121389: Sep 5, 2010 - 12:05 AM

[presure2]

sorry just trying to help, i know nothing about this I'm reading up on them now. So locking the voltage would keep injecting the same amount of fuel no matter how much boost?

no worries man, its all good.
just wanted to let you know about the diffrence between the 2 for future refrence.

yes, when you clamp the map sensor with a FCD like the one you posted, it sets the voltage at one point. for example, (just a generic voltage) it sets it at 2.5V, and thats all the map sensor ever puts out, no matter the conditions.
the one i am trying to get working allows the map sensor to work as normal below whatever voltage i set it at (4.1V, for example) and does not allow it to go above that.
the idea, is to set it as close to the boost cut as possible (which is ~18psi on a 3rd gen) so that when it clamps the voltage, its doing it when the ecu is opening the injectors at full duty cycle.