Injector conditions, idle-behavior and settingsSince I started VEMS-Configuration, a good Idle behavior was hard to get. But VEMS settings were not causing the problem. Reason for unstable idling were just dirty or worn out Injectors.
I also took this chance to change the Injectors on my Audi V8 (ABZ) to the newer Bosch EV6 design #0280155712 (Opel,Vauxhall) and now trying to get proper settings (1.1.81). But before installing these used ones, I put them under a ultro-sonic treatment and tested them on my selfmade Injector Teststand.
My demand was to get a clear spray pattern, same amount of petrol running trough and a resitance-variation close to +-0.05 Ohm. I bought 2 sets of used V6 Injectors and finally got 8 out of 12 in serviceable conditions.
Now the result is a smooth and very stable idling just with a proper IAC Reference curve and ignition advance idle control. Provided that VE table squares lambda-target at idling.
Injector-Settings, here is my understanding/setting so far, as I gathered Information:
Injector data:Resistance (Ohm): 15.95
Operating pressure (kPa): 300
Q-stat (at operating pressure) (g/min): 160
Q-stat with 300 kPa (ml/min): 229
q-dyn with 300 kPa, ti 2,5 ms (g/1000 Imp.): 4.9
Injector open time @13.2V [injopen-max:4080,min:0 µs]set to 0 , as lag-time is covered by Injector Effective Rampup and Injector Rampup Voltage Compansation
Injector Effective Rampup [injocfuel-max:6120,min:0 µs]this setting I did calculate with k-factor from injrampup_battfac=4080 at 13.2V.
a plain calculation (by GinstK) is using Injector-specs to get the inert time slice
with no lag-time, it would squirt 6.67mg in 2.5ms (160g/min->2.67mg/ms x 2,5)
according to specs -> 4.9mg within 2.5ms PW
4.9mg relates to 1.84ms if lag is subtracted.
So lag time becomes 2.5-1.84 = 660µs supposing @ 13.2V (K -> 0.775 with 4080)
660µs = K*2/3*Injector Effective Rampup
Injector Effective Rampup = 660*1.5/0.775 = 1277µs
Injector Rampup Voltage Compansation [injrampup_battfac-max:4080,min:0 µs]using consideration from GinstK:
For injrampup_battfac = 4080:
PWefframpup=k*2/3*inj_eff_ramup_time
k=1.0@7V
k=0.90@10V
k=0.78@13V
k=0.737@15V
k=0.70@16V
If injrampup_battfac is reduced, k gets closer to 1.0
example:
if 2040 used k=0.85@16V
if 0 - k=1.0 always
Injector Voltage Compansation [battfac-max:4080,min:0 µs]guessing 400µs (figuring out, if I need this setting anyway)
These settings are working fine now, but I suppose - in my case - the injector voltage compensation settings don`t have that much influence, while the strong 120A Generator delivers between 14.2V and 14.4V from start up, with all current consuming equipment...in my small 89Q coupe.
Years ago I started with Tri-X (now Trijekt), meanwhile I changed to VEMS. Fact is, they used to have a simple method for voltage compensation, adding injection time. Just setting two points for a straight line, for example: 1ms@10V and 0.4ms@14V, which worked fine - in my experience - with standard injectors up to 440ccm/min. This could be an option for a simplified setting.
Leonhard
