My flyback page
Original problem:
I cannot get stable idle and low load (<2500rpm) area using lambda values above 0.9. Actually I need to use 0.85-0.88 on these areas. This engine is happy to operate on 1-1.05 lambda with stock (injector, ecu, fuel) setup.
Original setup:
BMW M30B34 turbo engine, 1200cc low-Z (2.0 Ohm) injectors with E85 fuel. In-line resistors from webshop and 30V transient flyback diode.
Experiment #1:
Just tried alternative flyback from MembersPage/GintsK/FlybackForLowZ
- I've got slightly faster closing than 30V zener setup (my idle lambda changed from ~0.9 to ~0.94), with resistors still inline. Note that effective flyback voltage also rose from 30V to 36V.
Experiment #2:
Resistors removed and changed to pwm mode. It was very sensitive to pwm duty %, in fact I couldn't get stable opening below 75% duty. This way low load lambda control results was better, actually I set VE to lambda=~1 values on low load which was original goal. On high load this high duty pwm fried one of my injectors. (10A fuse still intact)
My observations show that going to 36V switched flyback will accelerate closing of injectors significantly, and omitting inline resistors will accelerate opening of injectors also.
As it seems these injectors cannot handle this high current load, I thought abut some sort of switching flyback.
Switching flyback strategy #1:
No inline resistors, PWM mode, low voltage AND high voltage flyback switched by per-channel flyback logic. Low voltage flyback during the pwm phase and high voltage flyback switched immediately after closing. (64us?)
Switching flyback strategy #2:
Inline resistors, no PWM mode, high voltage flyback.
On injector opening switching logic switches a direct connection between FET and injectors (avoiding inline resistors).
After ~1ms it switches off, so resistors will limit current afterwards.
I'm interested in your ideas here...