Flyback?

[gox]

When i was soldering the board,i added this flyback wire



Now,when i want to connect the injectors do i need to add one more wire from Injectors +Vbatt to EC36Pin23?

Since i will later use lowZ injectors can i add TS diode to this wire on board or do i need to put a wire from EC36Pin23 to +Vbatt with TS diode?

Tnx

Gogi

[rob@vems.co.uk]

Yes EC36-pin23 goes to injector +Vbatt
LowZ injectors are best run with a power resistor and a transient suppression diode and no PWM.
If you want to run LowZ with PWM then no TS diode or resistors.

[gox]

Yes EC36-pin23 goes to injector +Vbatt
LowZ injectors are best run with a power resistor and a transient suppression diode and no PWM.
If you want to run LowZ with PWM then no TS diode or resistors.

Tnx...

About PWM...i didnt get there so far,so i dont clearly get it what is PWMing

[rob@vems.co.uk]

PWM pulses the voltage very quickly, so if you have 50% duty cycle it means that the voltage is flowing for 50% of the time - this is too fast for the injector to close, so it stays open but consumes half the power.
Some get good results with PWM and LowZ injectors, others don't.  I take the path with the least complication and run 50W 6R8 resistors a TS diode and no PWM.

[gox]

Tnx
I have Power Resistors and TS diode.Since i`m going to use lowZ on my turbo engine,we will talk about that when the time comes,now i`m using highZ stock on my N/A engine.Just want make sure that i got thinks right and then switch to turbocharged,my wire harness still can stay.
Curently i`m studing your text for Idle stepper (BMW Stock)

Here is what Mattias said to me:

Use a Schottky diode (SR806 is good) to protect the injector FETs if you use those outputs. If you use IGBTs then use the Schottkys anyway because the built-in diode protection clamps at much too high voltage to efficiently control the ICV solenoid flyback current. If you use free stepper chip outputs then you don't need the flyback diodes.

The VEMS Genboard only provides ground. One ground to close the solenoid and another to open the solenoid. The third wire is +12V. It's easy.

What is Schottky didode? 
I think you said on some topic here that we cant use stepper outputs for that one?

Tnx

(i know i`m little boring but this is my first project)

Gogi

[gox]

From what I understand I need to use Gergelys settings http://quasar.dynaweb.hu/~lezsi/bmw/attila/configtables20060402.txt so I guess these settings apply to IAC:
iac_step_seq=D8
iac_conf=38
iac_max_steps=96
iac_tps_thres=0D
iac_cold_idle_temp=BF
iac_warm_idle_temp=C6
iac_cold_rpm=73
iac_warm_rpm=5F
iac_cold_start_pos=99
iac_warm_start_pos=80
iac_afterstart_rpm=0A
iac_afterstart_duration=0A
iac_speed=06
iac_kp=25
iac_ki=20
iac_kd=30
launch_rpm=C0
iac_integral_limit_dec=14
iac_integral_limit_inc=64
iac_integral_deadband=0A
iac_deadband=05
als_cut_maxtps=01
iac_overclose_interval=0A
iac_ref_pos[0]=99
iac_ref_pos[1]=99
iac_ref_pos[2]=99
iac_ref_pos[3]=8E
iac_ref_pos[4]=87
iac_ref_pos[5]=85
iac_ref_pos[6]=80
iac_ref_pos[7]=7A
iac_ref_pos[8]=78
iac_ref_pos[9]=75
iac_sol_channel=36
iac_ign_slope=18
softrpm_range=18
iac_ign_advance_limit=10
iac_ign_retard_limit=18
iac_ign_threshold=03


i have firmware 1.0.73 whis will work right,since it was wrote for 1.0.30 i think

[VemsedE36]

Yes EC36-pin23 goes to injector +Vbatt
LowZ injectors are best run with a power resistor and a transient suppression diode and no PWM.
If you want to run LowZ with PWM then no TS diode or resistors.

Rob,

I have bought the ecu with Flyback 30v setup, I also have 6,8ohm resisters to running low impedance injectors
Can I supply (+)  from ignition relay to low impedance injectors? And connect EC36/23 to battery (+)?

Thanks,

[rob@vems.co.uk]

That sounds a perfectly good idea - as when you switch off the ignition the flyback still has a return path.

[VemsedE36]

That sounds a perfectly good idea - as when you switch off the ignition the flyback still has a return path.

Thanks for confirmation.

[GintsK]

That sounds a perfectly good idea - as when you switch off the ignition the flyback still has a return path.

From where?

[rob@vems.co.uk]

Ground to power source

[GintsK]

Injectors are disconnected from ground when  flyback pulse occurs.  IMO Flyback circuit gives pulse from injector supply back to injector supply - virtually flyback clamping circuit is nothing elese than Zener diode in parallel with injector coil. I do not see the sense use for this another wire than injector supply. Otherwise we risk to get negative unclamped flyback pulse in unpowered injector supply. No?

Gints

[rob@vems.co.uk]

I think we need a diagram to be 100% sure

[GintsK]

Here it is! Left side is our case:

Quite similar as flyback clamping diode inside relays. Only differences - we want to allow higher voltage  for faster closing time (purpose of Zener) and we have additional diodes for separating injector circuits each from other.

[rob@vems.co.uk]

So that's the flyback connecting to +12v.
If it goes to the switched side of the relay and the relay is open there is no feedback path, if it goes to the battery then there is a path from ground side of the injector coil to the battery.