MicroSquirt.com read only forum (Jan.15,2018)

Hi guys i have been lurking the forums and reading a bunch about the microsquirt. I have not yet purchased it but will very soon along with the simulator.

I would like for someone to assure me that my planned configuration will work... I am still a little confused as i cant find my exact intended configuration in the forums and there is not a lot of info out there on odd fire.

I want to control fuel and spark. I have only one VR sensor on the crank, with a 36-1 trigger wheel. I have two seperate coils that are each fed two wires. A constant power (+12) and an ECM controlled ground. These are not logic level coils. I plan to use two BIP373 coil drivers and use them to pull the coils to ground using the signal level microsquirt outputs.

can someone point me in the right direction in terms of what my initial configuration parameters need to be? I need coil 1 to fire once, coil 2 to fire once, injector 1 to squirt once, and injector 2 to squirt once for each 720 degrees of rotation. I have direct port injection.

Thanks and sorry if this has been asked before!

I bought the Microsquirt from DIYAutotune... already shipped. smokin' fast!

Hi TurboVic1,

Odd fire V twins are not my thing, but as nobody else has chipped in, I'll give you some pointers...in section 1A here ....you can see you can do odd fire, but not with a missing toothed wheel. You use a single toothed wheel & two sensors, one for one cylinder and another for the other one. This works OK, but doesn't really help you if you can't fit a second sensor on the crank 50º from the other.

The other option, 1b, is to use 2 cam mounted sensors, but again this is not for a toothed wheel.

I don't know if the "odd fire offset" option can be incorporated with one of the other dual spark modes to achieve what you want either, and I have to agree it is slightly confusing.

Mike

PS The only other "option" is the MSExtra firmware which has modes for a 32-2 wheel in a HD engine, and a 12-3 wheel for a Honda VTR, but if you want to discuss this, you will have to post on that forum, in this section

Hmm... Thanks for the response i was starting to wonder if i put it in the wrong place!

Anyway, i thought i read that i could still do odd fire with just a 36-1 trigger wheel - maybe it was by doing wasted spark or something like that - odd fire is a separate parameter from dual spark i thought. I hope i didn't just wast a ton of money on a microsquirt module if i cant use it without modifying my bike! Somehow the stock ECU makes it fire "odd" so i don't understand why microsquirt isn't advanced enough to do the same with the same sensors.

Also, if i can still use the odd fire, what does that setting mean for the injector timing? Does that also shift to match or am i going to have 1 of the 2 injectors firing at some weird time?

Take a look at configuration 3A at the link above. A single missing-tooth crank wheel can do wasted spark odd-fire as long as each cyl (in a twin) has its own coil.

Thanks dontz125 for clarifying that, but it's was confusing (for me) reading the fragmented documentation.
After reading section 3 in the dual spark bit again, it makes sense now...fires coil 1 & then coil 2 after x skip teeth, and so it's a wasted spark configuration, because there is no cam input.

TurboVic1, the injection timing is staggered pro rata, but I assume it squirts every 360º not 720º like you queried in your original post, because your trigger is crank based.
Sorry for the confusion, like I said V twins are not my thing...but I am going to try the "option 3" mode on my 180 degree flat twin set up, just to check it out.

Mike

24c wrote:Thanks dontz125 for clarifying that, but it's was confusing (for me) reading the fragmented documentation.
After reading section 3 in the dual spark bit again, it makes sense now...fires coil 1 & then coil 2 after x skip teeth, and so it's a wasted spark configuration, because there is no cam input.

TurboVic1, the injection timing is staggered pro rata, but I assume it squirts every 360º not 720º like you queried in your original post, because your trigger is crank based.
Sorry for the confusion, like I said V twins are not my thing...but I am going to try the "option 3" mode on my 180 degree flat twin set up, just to check it out.

Mike

I had to look up pro rata, lol. "in proportion" is good, so what you are saying is that each cylinder will get squirted twice per 720 degree engine cycle (4-stroke engine here i forgot to include that)?

I am already worried i will not be able to provide low enough fuel pressure at idle with the big injectors i will have to use, I would hate to have to squirt each cylinder twice per engine cycle because i will already be pushing the minimum pulse duration on my injectors at one squirt per cycle.

just to clarify on the wasted spark, yes i have two coils, one per cylinder... only one pickup on the trigger wheel just like 3A. So when i make my BIP373 circuit i only need one correct? one igniter circuit and one of the ignition outputs feeding into both of my coils?

and thanks for the link to you both, I had not found that before!

sorry i spoke too soon... i need to use both ignition outputs had to read 3A again!

Dropping your fuel pressure at idle has to be done carefully - too low and your droplets get too big.

Do you have a Microsquirt (boxed unit) or a Microsquirt Module? The Extra code allows a 3rd and 4th injector channel with the module, so staged injection is an option. Also, the Extra code can use the single MAP sensor for phase discrimination on singles and odd-fire twins, so you can have sequential injection and COP spark with the hardware you already have.

i purchased the boxed unit but i am planning to pull it out and re-box it so i can use the same header as my stock ecu and literally unplug my stock ecu and plug in the micro. I was under the impression that the boxed unit had 1 or two additional features - i don't understand what they are but i went with it thinking i wanted the latest thing.

what is the minimum pulse width the micro can output? I think i will be able to have good idle for this engine without even dropping the fuel pressure at all... My fuel pressure regulator does not have a reference to vacuum, which i think means that it tries to always maintain the same pressure regardless of load. That is the only reason i am thinking i will be even close to having a problem with big injector/bad idle stuff. The injectors i will go with will be in the 650-750cc range, so they really aren't THAT big. I may have to modify my fuel pump situation though to get more flow anyway, so when i do that i could put in a proper regulator to drop the pressure to ~40 psi down from the current 49 at idle.