# Megasquirt Rising edge vs. Falling Edge: an explanation



## TheTimob (Sep 13, 2003)

I made this picture to explain:








This is a difference in Audi vs Volkswagen distributors' Hall sender shutters. The Megamanual was no help in figuring this out.
Getting this wrong could cause your engine to run only with the distributor advanced or retarded about 45° and 55°, and whacky advance problems, sparking on the wrong terminal, and head injuries due to you hitting your head against the wall!


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## B4S (Apr 16, 2003)

*Re: Megasquirt Rising edge vs. Falling Edge: an explanation (timbo2132)*

Cool, good info!
Does this apply to Digifant dizzies too? I'd imagine they are similar to the Audi one vs the vac adv/ret rabbit dizzy you've posted a pic of.


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## need_a_VR6 (May 19, 1999)

*Re: Megasquirt Rising edge vs. Falling Edge: an explanation (B4S)*

In MS2 you can trigger on either, but on the Audi one, if you trigger falling edge with certain board mods it puts you in next cyl mode. As long as you're aware of that, it's fine. Syncing the timing would have caught it in any case.


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## Svedka (Jul 4, 2008)

*Re: Megasquirt Rising edge vs. Falling Edge: an explanation (timbo2132)*

well i have an audi 2.0 bottom end and i had some problems with my spark order is there a fix for this i also need help wit tables for my ms v2.2 i just posted a new thread please help


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## chrisbmx68 (Aug 14, 2003)

I just ran out to my car and the digi II dizzy I have modded to work in my aba block has the same window setup as the audi 3a dizzy. so what does this mean in terms of configuring my megasquirt properly? I have a ver 2.2ecu doing fuel and spark


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## chrisbmx68 (Aug 14, 2003)

I figure I would add that on my car it doesn't idle well unless you set the trigger angle between 48-55 but pings on top like that. Idles like junk if you set the trigger angle to 62-65 but runs ok up top


_Modified by chrisbmx68 at 1:07 AM 7-7-2008_


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