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GM HEI, stepper IAC, and wiring up the bypass. help?
Posted: Mon Mar 06, 2006 12:14 pm
by flyguyeddy
Ok, im running a GM DIS setup (similar to the HEI setup) and the stepper IAC with this engine. i need to know is there a way to operate the bypass with the megasquirt as they do it with the extra code, or do i have to rig up a relay? i would like to not have to make a relay setuyp, but if i have to i will. btw, im using a diy-autotune harness, so i can pretty much only use the wiring thats in the bundle. any assistance?
runing v3 board and 2.33 (i think)
Posted: Wed Mar 08, 2006 6:05 am
by Bernard Fife
is there a way to operate the bypass with the megasquirt as they do it with the extra code, or do i have to rig up a relay?
flyguyeddy,
There are two ways to do this besides a relay.
The first is to use
'trigger rise' for the
'Cranking trigger' setting. This essentially causes the module to behave the same as if the byapass were connected, but MegaSquirt-II is still involved.
The second way to do this is to use the
spare port outputs. Since you have an IAC, you can use the FIdle output with a pull-up resistor/5V voltage source. (You connect the Vref to the HEI bypass line through a 1k Ohm resistor to limit current.) Then set the conditons so the Fidle LED is off when the rpm is <= to the cranking rpm (or the engine bit>2 and <5, etc., etc.). You could also reassign one of the LEDs for this function as these already have a pull up.
Lance.
Posted: Wed Mar 08, 2006 6:03 pm
by DCU1976
use 'trigger rise' for the 'Cranking trigger' setting. This essentially causes the module to behave the same as if the byapass were connected, but MegaSquirt-II is still involved.
What are the Pro's and Con's with using this setting, and where exactly is it. Thanks!