Injector Fire Timing?

[750steve]

Well i am learning so i need to ask some very basic questions!

My original firing order for coils is 1,2,4,3 .............. thing is i don't know when the injectors are supposed to fire (or is it all linked in microsquirt?)

I'll be using 2 crank pickups & a single toothed wheel. The pickups are 180 dedrees apart.

The injectors will be wired in 2 banks of 2 (this is correct, right?), 2 injectors for cyl #1 & #4 then 2 for cyl #2 & #3, they are High Imp injectors.

[Matt Cramer]

That wiring sounds right to me.

[750steve]

Thanks Matt. It's not the wiring I'm wondering about though its when the injectors fire I'm questioning.

[grippo]

Fuel timing for this is set by the InjStart variable as a % of the tach cycle, which is the time between sensor1 and sensor2 signals. In your case the sensors are separated by 180 deg, so a 33% InjStart would cause the injectors to fire 60 deg after each sensor pulse. The cylinder wiring as you described should be correct. Set the Number of Teeth to 0 because you are not in a wheel decode mode.

[dontz125]

Can the InjStart variable be set by the user, either in the ini or TS?

[grippo]

Its set in TS, but exactly how depends on the code version. The best code to use for the Dual Sensor setup is code 2.920. If you use 3.8x code, you have to disable auto_trigger.

[750steve]

Thanks for chiming in guys! I'll use that version Grippo if you recommend it.

Will the 2.920 code lose anything over the 3.8x code? Is there anywhere where i can see what codes have which functions?

From what i've been reading up on the firing i need to set mine to fire each injector twice every 720 degrees. Doesn't this mean then that i need to set my duty cycle to 50%? Is that correct?

So, really it doesn't matter when the injectors fire does it, just as long as it's twice per 720 degrees as the inlet valve only opens once every 720 degrees anyway.

The window is becoming less foggy! lol

[grippo]

For your mode it will inject cyl 1 every time it gets a pulse from sensor 1 and same for cyl, sensor 2. Since these are crank sensors it will inject 2x per 720 deg cycle. The timing of the injections isn't critical except to avoid injecting during the overlap period when some fuel may be lost through the exhaust.

If you are already set up for 3.8x I would use it and if it works great. If you are just starting I would use 2.92 and if it works I would consider upgrading, but the critical thing in either case is keeping separate msqs so you can roll back if something doesn't work. The main reason to use 3.8x code is possibly more robust comms especially with wireless tuning. Most of the other 3.8x features are for sequential setups.

[750steve]

Ok, well i have bought one but havent got it im my hands yet as its coming from USA (im in the UK).

Im currently buying coil leads, i know to get resistor caps (plugs are resistor type too) but what material should the leads be made from & should they be sheilded or suppressed? Basically, what type of lead should i buy? Will uS be affected by interference?

Sorry if that seems off topic, i find it best to ask questions before i try to set it all up

[dontz125]

Im currently buying coil leads, i know to get resistor caps (plugs are resistor type too) but what material should the leads be made from & should they be sheilded or suppressed? Basically, what type of lead should i buy? Will uS be affected by interference?

Any EFi controller is tremendously vulnerable to EMI. That said, we touched on this the other day; resistor plugs and caps will do an excellent job of keeping the electronics happy. Matt suggested normal spiral (stranded) copper leads. Basically, the stiff your bike came with!