How to find injector dead time's from scratch...
Posted: Fri Oct 19, 2012 12:27 pm
Okay, I figured I'd post this. Matt from Haltech gave me this info. Credit for the idea/algorithm goes to Scott.
Unfortunately its impossible for us to know all the details on all the injector types ever made by different manufacturers. There is a neat trick that Scott thought up for getting the injector dead times dialed in for any application using VE mode tuning, what you do is get the car up and running and warmed up, then let the car come to idle and tune the base fuel map to a stead AFR (I like to use somewhere around 14.5:1), then switch the injection mode from sequential to multipoint and restart the car and let it come back to idle (you may need to let it sit for a minute or so until any post start correction has finished), now check your AFR, if its not at the same AFR as it was sequential then adjust the injector dead time map until the AFR is half way between what is was previously and what it is now…..so for example:
Actual AFR in sequential mode at idle = 14.5:1
Switch to multipoint mode
Actual measured AFR in multipoint mode = 12:1
Adjust the injector dead time map until the actual AFR in multipoint mode reads 13.25.
Go back to sequential mode and the AFR should be 13.25 with the new dead time. The dead time is now set correctly. Go to the base fuel map to set AFR to whatever you desire.
This method will work only in VE mode and only when your not using the zero TPS map. When adjusting the injector dead time map I simply select the whole map and move it up or down as the shape of the injector dead time map doesn’t vary much across different injectors (ie at lower voltages all injectors have a longer dead time, at higher voltages its less).