Injection timing, when in the engine cycle and why?

marc426 · Post by **marc426** » Thu Jan 12, 2006 3:01 am

Hello everyone, still trying to know more about injection, i was just wondering if the injection occurs at a particular time in the engine cycle (like at xxÂ° before TDC or something like this...) and why? For example in a 6cylinders, injection will occur six times each two revolutions at a particular time each time, am I wrong?
Does a "basic" injection generating a pulse of xx ms each time the ignition coil is "fired" would work (i mean keeping the engine at a stable speed. Just feeding the the engine...). What retarding or advancing the injection time (xx ms after the coil triggering for example) would change?
These might seem dumb questions but i'm a beginner!
Thanks for your help

Marc

jsmcortina · Post by **jsmcortina** » Thu Jan 12, 2006 6:06 am

In a batch fire system like Megasquirt, the fuel is accurately timed but, there is no particular timing of the injection within the cycle.

See the Manual for a discussion of batch vs sequential and why it does not matter to 99% of users.

James

marc426 · Post by **marc426** » Sat Jan 14, 2006 2:18 pm

Thanks for your answer. I still have some questions though.http://rd500lc.free.fr/rdefi_fr.htm
I found the site above where they use a motronic injection which isn't a sequential injection right? They retrofit a two stroke four cylinder
But they somewhere say : "injection point has been set to 30Â° after the low (?) dead center. ??? Why? Moreover this is a 4cylinder engine so i just don't understand...
Thanks for your help

Marc

78Spit1500Fed · Post by **78Spit1500Fed** » Sun Jan 15, 2006 7:07 am

marc426 wrote:But they somewhere say : "injection point has been set to 30Â° after the low (?) dead center. ??? Why? Moreover this is a 4cylinder engine so i just don't understand...

This is a question for the author of that webpage.

I'm moving this question to the Pits forum because it is off topic and not MegaSquirt related.

-Brian