Injector dead time measurement.

[Jeremy Towers]

Hi. I am running a Holden L76 V8 with G4 Xtreme. I didn't seem to be able to find 'Injector dead time' info for the 40lb/hr used on this engine, so I have just used data for a Bosch injector for now. I have seen with some other ECU's dead time can be measured by changing the firing rate, then adjusting dead time value so that there is no change in Lambda readings between different rates. Can I do this on the G4 by changing to 'group fire' mode then making adjustments whilst switching the 'injection rate' between 360deg and 720deg? I realise it would only be applicable for one voltage cell. What do you think? Thanks Jeremy Towers

[Simon]

This would give you a good approximation. But to really get it right the injector would need to be tested on the bench.

[Top Tune NZ]

as a cheats way of setting this run the engine at a stable state and disconnect the alternaor adjust the dead time as battery charge decreases to keep the o2 reading stable.  you may need to turn the lights on to make this happen a little quicker

 

[Jeremy Towers]

Thanks for the tips guys. I imagine using both methods will get it close.

[martin battye]

TBH the way in which DDT hae described to set your inj lag time is the most effective way.. inj lag time is there so changes in voltage dont alter AF. so by setting in this way you have a sure fire way of getting it correct..

 

the only thing this doesnt account for is the base time (14v).. i tend to set this around the 0,8 mark and tune from there..

 

if you are finding that you cannot lean the motor out on idle (very large inj) then you may have to adjust this (but bare in mind some injectors cannot actually make a pulse under certain PW.

youll thank the day you did this is you ever lose an alternator since the car will drive pretty good down to 9v.

 

since setting inj lag in the disharge method also allows for the decrease in fuel flow from the pump. (to the point where base fuel pressure may even drop)