EFI Plenum Chamber Bypass Valve Pinout

stirlsilver · Post by **stirlsilver** » Sun Jan 07, 2007 7:03 am

Hi guys,
I'm soon to be putting on a EFI intake manifold onto my 3.5L for an LPG application and I have spotted the bypass valve on the back with 4 pins on it. Does anyone know what the pinout is? I want to use it on cold starts to let a little more air into the engine so it will idle when cold.
Thanks guys
Stirling

Post by **katanaman** » Sun Jan 07, 2007 11:08 am

this needs to be computer controlled so if your lpg doesn't have an ecu you cant use the air bypass. A way round this would be to fit the earlier thermotime valve from the flapper system that just needs + and - on it.

stirlsilver · Post by **stirlsilver** » Mon Jan 08, 2007 1:10 am

Ah, i'm up for a challenge. Shouldn't be anything a PIC can't handle

ChrisJC · Post by **ChrisJC** » Mon Jan 08, 2007 9:30 am

Just a guess, but it's probably a stepper motor. As you say, nothing a PIC (or AVR for non-masochists) can't handle.

Chris.

jwriyadh · Post by **jwriyadh** » Mon Jan 08, 2007 10:55 am

It is indeed a stepper motor, there is a 34993 driver chip in the ECU.

Check Megasquirt writeup for IAC on MegasquirtII for connector details.

Kataman is correct, a flapper type bypass valve would be simpler to install for just cold idle.

jw